Ear, nose and throat and eye disease

Francis Vaz, Nishchay Mehta, Robin D Hamilton

Disorders of the Ear

Anatomy and Physiology

The ear can be divided into three parts: outer, middle and inner (Fig. 30.1).

Figure 30.1 The anatomy of the ear. The ear is anatomically divided into outer, middle and inner ear, as indicated at the top. The outer ear consists of the pinna and external auditory meatus, and funnels sound energy to the middle ear, selectively amplifying sounds in the 2–4 kHz range by 15 decibels (dB, speech sounds). When sound energy passes from air in the outer ear to fluid in the inner ear, it loses 30 dB due to energy that is reflected at the interface of the two mediums. The middle ear acts as a transformer, increasing the pressure of the acoustic wave to account for the energy lost at this air–fluid interface. As the acoustic wave moves across the tunnel of the inner ear, passing from the oval window to the round window, it causes maximal vibration of the basilar membrane in a location that is specific to its resonant frequency. This vibration causes the hair cell to open its ion gates and an action potential to be propagated along a fibre of the cochlear nerve. The location of the nerve fibre and the strength of its action potential allow the central nervous system to construct meaning from the sound we hear.

The outer ear has a skin-lined tube 2.5 cm long leading down to the tympanic membrane (the ear drum). Its outer third is cartilaginous and contains hair and sebaceous and ceruminous glands, but the walls of the inner two-thirds are bony. The outer ear is self-cleaning, as the skin is migratory so there are no indications to use cotton wool buds. Wax should only be seen in the outer third.

The middle ear is an air-containing cavity derived from the branchial clefts. It communicates with the mastoid air cells superiorly, and the Eustachian tube connects it to the nasopharynx medially. The Eustachian tube ventilates the middle ear and maintains equal air pressure across the tympanic membrane. It is normally closed but opens via the action of the palatal muscles to allow air entry when swallowing or yawning. A defect in this mechanism, such as with a cleft palate, will prevent air entering the middle ear cleft, which may then fill with fluid. Lying within the middle ear cavity are the three ossicles (malleus, incus and stapes), which transmit sound from the tympanic membrane (Fig. 30.2) to the inner ear. On the medial wall of the cavity is the horizontal segment of the facial nerve, which can be damaged during surgery or by direct extension of infection in the middle ear.

Figure 30.2 Normal tympanic membrane. (a) Lateral process of malleus. (b) Handle of malleus. (c) Umbo. (d) Light reflex.

The inner ear contains the cochlea for hearing and the vestibule and semicircular canals for balance. There is a semicircular canal arranged in each body plane and these canals are stimulated by rotatory movement. The facial, cochlear and vestibular nerves emerge from the inner ear and run through the internal acoustic meatus to the brainstem (see Fig. 21.8).

Physiology of hearing

The ossicles, in the middle ear, transmit sound waves from the tympanic membrane to the cochlea. They amplify the waves by about 18-fold to compensate for the loss of sound waves moving from the air-filled middle ear to the fluid-filled cochlea. Hair cells in the basilar membrane of the cochlea detect the vibrations and transduce these into nerve impulses, which pass to the cochlear nucleus and then eventually to the superior olivary nuclei of both sides; thus lesions central to the cochlear nucleus do not cause unilateral hearing loss.

If the ossicles are diseased, sound can also reach the cochlea by vibration of the temporal bone (bone conduction).

Clinical Approach to the Patient with a Disorder of the Ear

Examination

The pinna and post-auricular region should first be examined for erythema, scars or swellings. An auroscope is used to examine the external ear canal whilst the pinna is retracted backwards and upwards to straighten the canal. Look for wax, discharge or foreign bodies. The tympanic membrane should always be seen with a light reflex anteroinferiorly. Previous repeated infections may cause a thickened, whitish drum but fluid in the middle ear may show as dullness of the drum. Perforations can be described as marginal if they involve the annulus, subtotal if the pars tensa is absent, and total if both pars tensa and the annulus are absent.

Rinne test

(Fig. 30.3.)

• Normally, a tuning fork, 512 Hz, will be heard as louder if held next to the ear (i.e. air conduction) than it will if placed on the mastoid bone (Rinne-positive).

• If the tuning fork is perceived louder when placed on the mastoid (i.e. via bone conduction), then a defect in the conducting mechanism of the external or middle ear is present (true Rinne-negative).

Figure 30.3 Rinne test. Comparing conduction of sound. A. Air conduction. B. Bone conduction.

Weber test

(Fig. 30.4.) A tuning fork placed on the forehead or vertex of a patient with normal hearing (or with symmetrical hearing loss) should be perceived centrally by the patient. A patient with unilateral conductive hearing loss will hear the sound loudest in the affected ear, whereas a patient with unilateral sensorineural hearing loss will report the sound to be loudest in the unaffected ear.

Pure-tone audiometry

The patient is asked to respond when they hear sounds presented as pure tones at varying sound intensities and frequencies. Sounds are presented to each ear (representing air conduction) and then to each mastoid in turn (representing bone conduction). An audiogram is produced by the lowest sound intensity that is reliably perceptible at each frequency tested at both ears and mastoids (Fig. 30.5).

Figure 30.5 Audiogram showing presbycusis (high-frequency loss).

The innervation of the pinna is from the auriculotemporal branch of the trigeminal and the first two cervical nerves (Fig. 30.6). Therefore, dental pain, temporomandibular joint dysfunction and upper cervical osteoarthritis can all present as otalgia. The ear canal is innervated by the above-mentioned nerves, and also by the facial and vagus nerves (Fig. 30.6). Hence Ramsay Hunt syndrome (varicella reactivation along the sensory division of the facial nerve) causes otalgia with ear canal vesicles, whereas cancer of the larynx and pharynx can occasionally present as otalgia due to referred pain along the vagus nerve. The middle ear is innervated by the glossopharyngeal nerve and therefore infections of the pharynx are associated with otalgia.

Figure 30.6 Sensory innervation of the ear. Due to the sophisticated embryology of ear structures, the sensory innervation is complicated. Therefore otalgia can be referred from many sites, and knowledge of aural sensory innervation is a good guide for a comprehensive examination in idiopathic ear pain. The auriculotemporal nerve (a branch of the mandibular division of the trigeminal nerve) supplies innervation to the superolateral pinna and roof of the external auditory canal (EAC). Pathology related to the upper teeth, temporomandibular joint and parotid gland can cause referred otalgia through this nerve. The lesser occipital nerve (a branch from the second cervical nerve) supplies most of the medial surface of the pinna and the posterior wall of the EAC. Cervical osteoarthritis can cause referred otalgia through this nerve. The greater auricular nerve (a branch from the third cervical nerve) supplies the inferior portion of the pinna, including the lobule. Cervical osteoarthritis can cause referred otalgia through this nerve. Arnold's nerve (a branch of the vagus cranial nerve) supplies the EAC floor and lateral surface of the tympanic membrane. Tumours of the larynx and pharynx can cause referred otalgia through this nerve. Jacobson's nerve (a branch of the glossopharyngeal nerve) supplies innervation to the mucosa of the middle ear, including the medial surface of the tympanic membrane. Tonsillitis and pharyngitis can cause referred otalgia through this nerve. CN, cranial nerve.

The discharging ear (otorrhoea)

Discharge from the ear is usually due to infection of the outer or middle ear. The most common cause is otitis externa, followed by otitis media with a perforated tympanic membrane (see above).

Cholesteatoma

Although cholesteatoma is a rarer cause of the otorrhoea, it has severe implications if missed and should be considered in any non-resolving or recurrent case of otorrhoea. Cholesteatoma is defined as keratinizing squamous epithelium within the middle ear cleft and can present with foul-smelling otorrhoea. Examination shows a defect in the tympanic membrane full of white, cheesy material. Mastoid surgery is required to remove this sac of squamous debris, as it can erode local structures such as the ossicles or facial nerve, or even extend intracranially to cause meningitis or an intracranial abscess.

Hearing loss

Deafness can be conductive or sensorineural and these can be differentiated at the bedside by the Rinne and the Weber tests (Box 30.1) or with pure-tone audiometry. Conductive hearing loss has many causes (Box 30.2) but wax is the most common.

Box 30.1

Testing hearing loss

Type	Defect	Rinne test	Weber test
Conductive	Outer or middle ear	Negative	Sound heard louder on the affected side
Sensorineural	Inner ear or more centrally	Positive	Sound heard louder in the normal ear

Perforated tympanic membrane

This arises from trauma or chronic middle ear disease when recurrent infection results in a permanent defect. Surgical repair is indicated only if the patient is symptomatic with recurrent discharge. The larger the perforation, the greater the impact on hearing.

Otitis media and otitis externa

As discussed above, both of these infections lead to hearing loss but the sequence of events will help differentiate the conditions: hearing loss is common and early in otitis media, but rare and late in otitis externa.

Secretory otitis media with effusion (‘serous otitis media’ or ‘glue ear’)

This is common in children because Eustachian tube dysfunction may lead to poorly ventilated middle ears. The vacuum created by poor ventilation leads to a non-inflammatory effusion. The effusion resolves naturally in the majority of cases but can persist or recur, causing a hearing loss that impacts on speech and language skills and on educational progress. The presenting complaint is hearing loss or speech delay but little association with otalgia.

Examination shows a dull tympanic membrane with loss of light reflex (Fig. 30.7) and occasionally fluid with air bubbles visible in the middle ear. Children with glue ear frequently have adenoidal hypertrophy and nasal blockage.

Figure 30.7 Secretory otitis media (glue ear). Auroscopic view of the tympanic membrane, which is dull with loss of light reflex.

Management involves insertion of a grommet (tympanostomy tube) into the tympanic membrane, which ventilates the middle ear cavity, if the symptoms are persistent and troublesome. Antibiotic–glucocorticoid ear drops are more effective than oral antibiotics. Adenoidectomy can be added to the procedure if there is a strong history of complete nasal blockage or recurrent upper respiratory tract infections. Grommets are extruded from the tympanic membrane as it heals (over 6 months to 2 years). Developmental outcomes are not improved by grommet insertions. In most children, the middle third of the face grows around the age of 7–14 years and Eustachian tube dysfunction is rare after this.

Otosclerosis

This is usually a hereditary disorder, in which new bony deposits occur within the stapes footplate and the cochlea. Characteristically seen in the second and third decades, it is more common in females and can become worse during pregnancy. The hearing loss may be mixed, and management includes a hearing aid or replacement of the fixed stapes with a prosthesis (stapedectomy). The choice of treatment is dependent on the patient. Surgery is an excellent option, with very good success rates in regular stapedectomists' hands, but it always carries a small risk of a complete hearing loss. Hearing aids, whilst safe, require the patient's compliance if they are to afford benefit.

Presbycusis

This is the most common cause of deafness. It is a degenerative disorder of the cochlea and is typically seen in old age. It can be due to the loss of outer hair cells (sensory), loss of the ganglion cells (neural) or strial atrophy (metabolic), or there can be a mixed picture. Ageing itself does not cause outer hair cell loss but environmental noise toxicity over the years is a major factor. The onset is gradual and the higher frequencies are affected most (see Fig. 30.5). Speech has two components: low frequencies (vowels) and high frequencies (consonants). When the consonants are lost, speech loses its intelligibility. Increasing the volume merely increases the low frequencies and the characteristic response of ‘Don’t shout. I'm not deaf!'

A high-frequency-specific hearing aid will do much to ease the frustrations of both the patients and their close contacts.

Noise trauma

Cochlear damage can occur, for example, from shooting without ear protectors or from industrial noise (see p. 59), and characteristically has a loss at 4 kHz.

Acoustic neuroma

This is a slow-growing benign schwannoma of the vestibular nerve (see p. 868), which can present with progressive sensorineural hearing loss. Any patient with an asymmetric sensorineural hearing loss or sudden sensorineural hearing loss should be investigated: for example, with a magnetic resonance imaging (MRI) scan.

Dizziness/vertigo

Vertigo is usually rotatory when it arises from the ear. The presence of otalgia, otorrhoea, tinnitus or hearing loss suggests an otologic aetiology. Vestibular causes can be classified according to the duration of the vertigo. Common causes are summarized below.

• seconds (<1 minute) – benign paroxysmal positional vertigo

• minutes to hours – Ménière's disease

• hours to days – labyrinthine or central pathology.

Benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) is thought to occur when otoconia (tiny crystals of calcium carbonate) are dislodged from the utricle into the semicircular canals, commonly the posterior canal. Positional vertigo is precipitated by head movements, usually to a particular position, and often occurs when turning in bed or on sitting up. The onset is typically sudden and distressing. The vertigo lasts seconds (<1 minute) and the phenomenon becomes less severe on repeated movements (fatigue). There is no serious underlying cause but it sometimes follows vestibular neuronitis (see p. 810), head injury or ear infection. It occurs in 50% of older people and is the most common cause of head injury in those under 50 years of age.

Diagnosis

Diagnosis is made on the basis of the history and by the Hallpike manœuvre (Fig. 30.8). A positive Hallpike test confirms BPPV, which can be cured in over 90% of cases by the Epley manœuvre. This involves gentle but specific manipulation and rotation of the patient's head to shift the loose otoliths from the semicircular canals.

The differential diagnosis includes a cerebellar mass, but in that case positional nystagmus (and vertigo) is immediately apparent (no latent interval) and does not fatigue.

Ménière's disease

This is a rare condition characterized by recurring, episodic, rotatory vertigo lasting 30 minutes to a few hours; attacks are recurrent over months or years. Classically, it is associated with a low-frequency sensorineural hearing loss, a feeling of fullness in the affected ear, loss of balance, tinnitus and vomiting. There is a build-up of endolymphatic fluid in the inner ear, although its precise aetiology is still unclear.

Management

Vestibular sedatives, such as cinnarizine, are used in the acute phase. Preventative measures, such as a low-salt diet, betahistine and avoidance of caffeine, are useful. If the disease cannot be controlled, then a chemical labyrinthectomy, perfusing the round window orifice with ototoxic drugs such as gentamicin, is used. Gentamicin destroys the vestibular epithelium; therefore the patient has severe vertigo for around 2 weeks until the body compensates for the lack of vestibular input on that side. The patient will happily trade occasional mild vertigo when the balance system is challenged against the unpredictable, severe and disabling attacks of vertigo involved in Ménière's disease. There is a risk of sensorineural hearing loss and complete vestibular failure if Ménière's starts in the previously unaffected side. The final option is surgical decompression of the endolymphatic compartment of the inner ear to relieve the endolymphatic hydrops.

Labyrinthine or central causes of vertigo

(See Box 21.13.) These are managed with vestibular sedatives in the acute phase. Most patients will settle over a few days but continuous true vertigo with nystagmus suggests a central lesion. A patient with a deficit of vestibular function due to viral labyrinthitis or neuronitis should be able to cease vestibular sedatives within 2 weeks; long-term use can give parkinsonian side-effects, delay central compensation and thus prolong the vertigo. Vestibular rehabilitation by a physiotherapist or audiological scientist can speed up the compensation process, although most patients will be able to do this themselves with time.

Tinnitus

This is a sensation of a sound when there is no auditory stimulus. It can occur without hearing loss and results from heightened awareness of neural activity in the auditory pathways. Patients describe a hissing or ringing in their ears and this can cause much distress. It usually does not have a serious cause but vascular malformation, such as aneurysms, or vascular tumours can be associated. In these cases, the tinnitus is pulsatile and most commonly unilateral.

Management

This is difficult. A tinnitus masker (a mechanically produced, continuous soft sound) can help. Cognitive behavioural therapy through audiological services are of use and rehabilitate patients well.

Disorders of the Nose

Anatomy and physiology

(Fig. 30.9.) The function of the nose is to facilitate smell and respiration:

• Smell is a sensation conveyed by the olfactory epithelium in the roof of the nose. The olfactory epithelium is supplied by the Ist cranial nerve (see p. 802).

• The nose also filters, moistens and warms inspired air and, in doing so, assists the normal process of respiration.

Figure 30.9 The anatomy of the nose in longitudinal section. IT, inferior turbinate; MT, middle turbinate; ST, superior turbinate; a, internal ostium; b, respiratory region; c, choanae.

The external portion of the nose consists of two nasal bones attached to the rest of the facial skeleton and to the upper and lower lateral cartilages. The internal nose is divided by a midline septum that comprises both cartilage and bone. This divides the internal nose in two, from the external nostril to the posterior choanae. The posterior choanae are in continuity with the nasopharynx posteriorly. The paranasal sinuses open into the lateral wall of the nose and form a system of aerated chambers within the facial skeleton.

The blood supply of the nose is derived from branches of both the internal and external carotid arteries. The internal carotid artery supplies the upper nose via the anterior and posterior ethmoidal arteries. The external carotid artery supplies the posterior and inferior portion of the nose via the superior labial artery, greater palatine artery and sphenopalatine artery. On the anterior nasal septum there is an area of confluence of these vessels (Little's area; Fig. 30.10A).

Figure 30.10 Little's area and nasal packing. A. Blood supply of Little's area on the septum of the nose. B. Nasal pack.

Clinical Approach to the Patient with a Disorder of the Nose

Examination

The anterior part of the nose can be examined using a nasal speculum and light source. Endoscopes are required to examine the nasal cavity and postnasal space.

Common Disorders of the Nose

Epistaxis

Nose bleeds vary in severity from minor to life-threatening. Little's area (Fig. 30.10A) is a frequent site of nasal haemorrhage. First aid measures should be administered immediately, including external digital compression of the anterior lower portion of the external nose, ice packs and leaning forward. The patient should be asked to avoid swallowing any blood running posteriorly, as this causes nausea.

Not infrequently, small, recurrent epistaxes occur and these may require a visit to the emergency clinic for an examination and simple local anaesthetic cautery with a silver nitrate stick. If the bleeding continues profusely, then resuscitation in the form of intravenous access, fluid replacement or blood, and oxygen can be administered. If further intervention is necessary, consideration should be given to intranasal cautery of the bleeding vessel, or intranasal packing using a variety of commercially available nasal packs (Fig. 30.10B). In addition to direct treatment of the epistaxis, a cause should be sought and treated appropriately (Box 30.3). If the above treatments fail, surgical ligation of the sphenopalatine artery can be undertaken endoscopically or an interventional arterial embolization can be performed for the problematic vessel.

Rhinitis

See pages 1076–1077.

Nasal obstruction

Nasal obstruction is a symptom and not a diagnosis. It can significantly affect a patient's quality of life. Causes include:

• Rhinitis (see pp. 1076–1077). The most common aetiology is allergy-based. Rhinitis results in erythema of the nasal mucosa and hypertrophy of inferior turbinates. If an allergen is identified, then allergen avoidance is the mainstay of treatment. Topical steroids and/or antihistamines can be tried. If rhinitis is severe, then referral to an allergy clinic for immunotherapy is warranted. Short-term benefit can be gained in severe nasal blockage by surgically reducing the inferior turbinate.

• Septal deviation. Correction can be undertaken surgically.

• Nasal polyps. This condition occurs with inflammation and oedema of the sinus nasal mucosa. This oedematous mucosa prolapses into the nasal cavity and can cause significant nasal obstruction. In allergic rhinitis (see p. 1075), the mucosa lining the nasal septum and inferior turbinates are swollen and a dark-red or plum colour. Nasal polyps can be identified as glistening swellings, which are insensate. Treatment with intranasal steroids helps, but if polyps are large or unresponsive to medical treatment, then surgery is necessary.

• Foreign bodies. These are usually seen in children who present with unilateral nasal discharge. Clinical examination of the nose with a light source often reveals the foreign body, which requires removal, either in clinic or in theatre, with a general anaesthetic.

• Sinonasal malignancy. This is extremely rare. The diagnosis must be considered if unusual unilateral symptoms are seen, including nasal obstruction, epistaxis, pain, epiphora (watery eye), cheek swelling, paraesthesia of the cheek, unilateral serous otitis media and proptosis of the orbit.

Sinusitis

Sinusitis is an infection of the paranasal sinuses that is bacterial (mainly Streptococcus pneumoniae and Haemophilus influenzae) or occasionally fungal. It is most commonly associated with an upper respiratory tract infection and can occur with asthma. Symptoms include frontal headache, purulent rhinorrhoea, facial pain with tenderness, and fever. Sinusitis can be confused with a variety of other conditions, such as migraine, trigeminal neuralgia and cranial arteritis.

Management

Treatment for a bacterial sinusitis includes nasal decongestants, such as xylometazoline; broad-spectrum antibiotics, such as co-amoxiclav because H. influenzae can be resistant to amoxicillin; anti-inflammatory therapy with topical corticosteroids, such as fluticasone propionate (nasal spray) to reduce mucosal swelling; and steam inhalations.

If the symptoms of sinusitis are recurrent (Box 30.4) or complications such as orbital cellulitis arise, then an ENT opinion is appropriate and a computed tomography (CT) scan of the paranasal sinuses is undertaken. Plain sinus X-rays are now rarely used to image the sinuses.

Box 30.4

Types of sinusitis

Type	Duration of symptoms
Acute	1 week to 1 month
Recurrent acute	>4 episodes of acute sinusitis per year
Subacute	1–3 months
Chronic	>3 months

CT scan of the sinuses (Fig. 30.11) or an MRI scan can demonstrate bony landmarks and soft tissue planes.

Figure 30.11 CT of the sinuses. An inverting papilloma (P) can be seen obstructing the right nostril, and there is mucosal thickening (M) of the right maxillary sinus.

Functional endoscopic sinus surgery (FESS) is used for ventilation and drainage of the sinuses.

Anosmia

Olfaction is mainly under the control of cranial nerve I, although irritant, unpleasant nasal sensations are carried by cranial nerves V, IX and X. Anosmia is a complete loss of the sense of smell and hyposmia is a decreased sense of smell:

• A conductive deficit of smell occurs if odorant molecules do not reach the olfactory epithelium high in the nose.

• A sensorineural loss of smell is incurred if the neural transmission of smell is affected.

• Some conditions predispose to a mixed (conductive and sensorineural) loss of smell.

The main cause of a loss of smell is nasal obstruction due to upper respiratory infection or nasal polyps. Other causes include sinonasal disease, old age, drug therapy and head injury/trauma. It is difficult to predict the speed and extent of recovery in the latter causes. In many, anosmia is idiopathic, but before this diagnosis is accepted, an assessment of the patient for the possibility of an intranasal tumour or intracranial mass should be undertaken.

Fractured nose

People with a fractured nose present with epistaxis, bruising of the eyes and nasal bridge swelling. Initially, it is often difficult to assess whether the bones are deviated, particularly if there is significant swelling. Reduction of the fracture should be undertaken in the first 2 weeks after injury and can be achieved by manipulation. However, if the fracture sets, a more formal rhinoplasty may have to be undertaken at a later stage. The patient should be examined for a head injury and the nose should also be checked for a septal haematoma (Fig. 30.12). This is painful, can cause nasal obstruction, is fluctuant to touch on the nasal septum, and requires immediate drainage to prevent destruction of the septal cartilage.

Disorders of the Throat

Anatomy and Physiology

The throat can be considered as the oral cavity, the pharynx and the larynx (Fig. 30.13). The oral cavity extends from the lips to the tonsils. The pharynx can be divided into three areas:

• The nasopharynx extends from the posterior nasal openings to the soft palate

• The oropharynx extends from the soft palate to the tip of the epiglottis

• The hypopharynx extends from the tip of the epiglottis to just below the level of the cricoid cartilage, where it is continuous with the oesophagus.

Figure 30.13 Normal anatomy of the throat.

Lying within the hypopharynx is the larynx. This consists of cartilaginous, ligamentous and muscular tissue that has the primary function of protecting the distal airway. The pharynx is innervated from the pharyngeal plexus.

In the larynx, there are two vocal cords that abduct (open) during inspiration and adduct (close) to protect the airway and for voice production (phonation). The main nerve supply of the vocal cords comes from the recurrent laryngeal nerves (branches of the vagus nerve), which arise in the neck, but on the left side pass down around the aortic arch and then ascend in the tracheo-oesophageal groove to the larynx.

Normal vocal cords in phonation vibrate between 90 (male) and 180 (female) times per second, giving the voice its pitch or frequency. A healthy voice requires full closure of the vocal cords with a smooth, regular pattern of vibration, and any pathology that prevents full closure will result in air escaping between the vocal cords during phonation and a ‘breathy’ voice.

Clinical Approach to the Patient with a Disorder of the Throat

Examination

Good illumination is essential. Look at the teeth, gums, tongue, floor of mouth and oral cavity. The tonsils, soft palate and uvula are easily seen, and a gag reflex (see p. 810) is present. The remainder of the pharynx and larynx can be inspected with a laryngeal mirror or flexible nasendoscope.

Examination of the neck for lymph nodes and other masses is also performed.

Common Disorders of the Throat

Hoarseness (dysphonia)

There are three essential components for voice production: an air source (the lungs); a vibratory source (the vocal cords); and a resonating chamber (the pharynx and nasal and oral cavities). Although chest and nasal disorders can affect the voice, the majority of hoarseness is due to laryngeal pathology.

Inflammation that increases the ‘mass’ of the vocal cords will cause the vocal cord frequency to fall, giving a much deeper voice. Thus listening to a patient's voice can often give a diagnosis before the vocal cords are examined.

Nodules

Nodules (always bilateral and more common in females) and polyps (Fig. 30.14A) are found on the free edge of the vocal cord, preventing full closure and giving a ‘breathy, harsh’ voice. They are commonly found in professionals who rely on their voice for their livelihood, such as teachers, singers and lawyers. They are usually related to poor technique of voice production and can usually be cured with speech therapy. If surgery is needed, great care must be taken to remain in the superficial layers of the vocal cord in order to prevent deep scarring, which leaves the voice permanently hoarse.

Reinke's oedema

This is due to a collection of tissue fluid in the subepithelial layer of the vocal cord (Fig. 30.14B). The vocal cord has poor lymphatic drainage, predisposing it to oedema. Reinke's oedema is associated with irritation of the vocal cords by smoking, voice abuse, acid reflux and, very rarely, hypothyroidism. Treatment is to remove the irritation in most cases, but surgery to incise the cords and reduce the oedema will also allow the voice to return to its normal pitch.

Acute-onset hoarseness

Hoarseness, in a smoker, is a danger sign. Any patient with a hoarse voice for over 6 weeks should be seen by an ENT surgeon. Other red flag symptoms will require urgent laryngoscopy (Box 30.5). The voice may be deep, harsh and breathy, indicating a mass on the vocal cord (Fig. 30.15), or it can be weak, suggesting a paralysed left vocal cord secondary to mediastinal disease, such as bronchial carcinoma.

Box 30.5

Red flags for hoarseness requiring urgent laryngoscopy

• Heavy smoking

• High alcohol intake

• Haemoptysis

• Dysphagia

• Pain, including otalgia

• Increasing dyspnoea

Figure 30.15 Carcinoma of the right cord.

Early squamous cell carcinoma of the larynx has a good prognosis. Treatment is with carbon dioxide laser resection or radiotherapy. Spread and growth of the tumour can lead to referred otalgia, and, if the tumour is significant in its size, requires a laryngectomy (removal of the voicebox), with a neck dissection to remove the affected glands in the neck. A patient with a paralysed left vocal cord must have a CT of the neck and chest. Medialization of the paralysed cord to allow contact with the opposite cord can return the voice and give a competent larynx. This can be done under local or general anaesthesia, producing an immediate result whatever the long-term prognosis of the chest pathology.

Stridor

Stridor, or noisy breathing, can be divided into the following types:

• Inspiratory: obstruction is at the level of the vocal cords or above.

• Mixed (both inspiratory and expiratory): obstruction is in the subglottis or extrathoracic trachea.

• Expiratory: obstruction is in the intrathoracic trachea or distal airways.

All people with stridor, both paediatric and adult, are potentially at risk of asphyxiation and should be investigated fully. Severe stridor may be an indication for either intubation or a tracheostomy (Box 30.6).

Box 30.6

Indications for tracheostomy

• Upper airway obstruction (real or anticipated)

• Long-term ventilation

• Bronchial lavage

• Incompetent larynx with aspiration

Management

Tracheostomy

Tracheostomy tubes (Fig. 30.16) are:

• Cuffed or uncuffed. A high-volume, low-pressure cuff is used to prevent aspiration and to allow positive-pressure ventilation.

• Fenestrated or unfenestrated. A fenestrated cuff has a small hole on the greater curvature of the tube (both outer and inner), allowing air to escape upwards to the vocal cords; the patient can therefore speak. This tube often has a valve that allows air to enter from the stoma but closes on expiration, directing the air through the fenestration.

Figure 30.16 Tracheostomy tubes and their accompanying components.

Most long-term tracheostomy tubes have an inner and an outer tube. The inner tube fits inside the outer tube and projects beyond its lower end. A major problem with a tracheostomy tube is crusting of its distal end with dried secretions, and this arrangement allows the inner tube to be removed, cleaned and replaced as frequently as required, without disrupting the outer tube.

When to decannulate a patient is often a difficult issue if laryngeal competence is unclear. Movement of the vocal cords requires an ENT examination and a speech therapist's involvement. The tracheostomy tube itself can also produce problems due to compression of the oesophagus with a cuffed tube and prevention of the larynx from rising during normal swallowing.

Tonsillitis and pharyngitis

Viral infections of the throat are common and, although many practitioners may be under pressure from the patient to give antibiotics, they should not be used. The vast majority of infections are usually self-limiting, settling with bed rest, analgesia and encouragement of fluid intake. Fungal infections, usually candidiasis, are uncommon and may indicate an immunocompromised patient or undiagnosed diabetes.

Tonsillitis

Tonsillitis, with a good history of pyrexia, dysphagia, lymphadenopathy and severe malaise, is usually bacterial; β-haemolytic streptococcus is the most common organism, which responds to penicillin V.

Glandular fever

Glandular fever (see p. 258) can also present with tonsillitis. Although, clinically, the tonsils have a confluent white exudate, there is often a petechial rash on the soft palate and an accompanying lymphadenopathy.

Quinsy (peritonsillar abscess)

Quinsy is a collection of pus outside the capsule of the tonsil, usually located adjacent to its superior pole. The patient often has trismus, making examination difficult, but the pus pushes the uvula across the midline to the opposite side. The area is usually hyperaemic and smooth but unilateral tonsil ulceration is more likely to be a malignancy. In either case, urgent referral to an ENT specialist is essential.

Indications for a tonsillectomy are shown in Box 30.7. This is carried out under a general anaesthetic and current surgical techniques include diathermy dissection, laser excision and coblation (using an ultrasonic dissecting probe). There are strong advocates for each technique and much will depend on the individual surgeon's preference. Some departments carry out tonsillectomy as a day-case procedure, as most reactionary bleeding will occur within the first 8 hours postoperatively.

Box 30.7

Indications for tonsillectomy

• Suspected malignancy

• Obstructive sleep apnoea due to tonsillar hypertrophy

• Recurrent tonsillitis: 5 attacks a year for at least 2 years

• Quinsy in a patient with a history of recurrent tonsillitis

Snoring

Snoring is caused by high-pressure airflow, resulting in vibration of soft tissue above the level of the larynx. It is a common symptom (50% of 50-year-old males will snore to some extent) and can be considered to be related to obstruction of three potential areas: the nose, the palate or/and the hypopharynx (see Fig. 24.26). There is a strong association between snoring and sleep-disordered breathing, such as in obstructive sleep apnoea (see pp. 1085–1086).

The Epworth questionnaire (see Box 24.17) can assist in identification of sleep apnoea. People with a history of habitual, non-positional, heroic snoring (can be heard through a wall) require a full ENT examination and can be investigated by sleep nasendoscopy, in which a sedated, snoring patient has a flexible nasendoscope inserted to identify the source of vibration.

Nasal pathology, such as polyps, can be removed surgically with good results and most patients will benefit from lifestyle changes, such as weight loss. Stiffening or shortening the soft palate via surgery, often using a laser, can help for palatal snorers but hypopharyngeal snorers require either a dental prosthesis at night to hold the mandible forwards or continuous positive airway pressure (CPAP) via a mask (see p. 1086).

Dysphagia

Dysphagia (see pp. 365–366) occurs because of any lesion between the throat and stomach. The two conditions described here are the ones usually dealt with by ENT departments. Gastroenterology departments see causes further down the gullet.

Pharyngeal pouch

A pharyngeal pouch is a herniation of mucosa through the fibres of the inferior pharyngeal constrictor muscle (cricopharyngeus) (Fig. 30.17A). An area of weakness known as Killian's dehiscence allows a pulsion diverticulum to form. Patients present with a neck swelling following a failed swallow attempt. They can occasionally compress the swelling to allow food particles to be pushed back into the oesophagus. They may also complain that a gurgling sound is heard in the neck following a swallow as liquid and food collect in the pouch. Occasionally, patients present with recurrent pneumonia following aspiration of food into the trachea. Diagnosis is made with a barium swallow (Fig. 30.18) and treatment is surgical, either via an external approach through the neck where the pouch is excised or, more commonly, via endoscopy with stapling of the party wall (Fig. 30.17B).

Figure 30.18 Pharyngeal pouch shown on barium swallow.

Foreign bodies

Foreign bodies in the pharynx can be divided into three general categories: soft food bolus, coins (smooth) and bones (sharp). Soft food bolus can be initially treated conservatively with muscle relaxants for 24 hours. Impacted coins should be removed at the earliest opportunity but sharp objects require emergency removal to avoid perforation of the muscle wall.

If the patient perceives the foreign body to be to one side, then it should be above the cricopharyngeus and an ENT examination will locate it; common areas are the tonsillar fossae, base of tongue, posterior pharyngeal wall and valleculae. Radiology will identify coins, and a clinical decision can be made to see whether a coin will pass down to the stomach; in this case no further treatment, is required as it will exit naturally. Some departments advocate the use of a metal detector to monitor the position of the coin in the patient, who is usually a child or has a mental disorder. Fish can be divided into those with a bony skeleton (teleosts) and those with a cartilaginous skeleton (elasmobranchs), and therefore radiology is useful only in some cases. Radiology can also identify air in the cervical oesophagus, indicating a radiolucent foreign body lying distally. A soft tissue lateral neck radiograph is the investigation of choice to delineate some of the features above.

Globus pharyngeus

This is a functional disorder and is not a true dysphagia. It is a condition with classic symptoms of an intermittent sensation of a lump in the throat. This is perceived to be in the midline at the level of the cricoid cartilage and is worse when swallowing saliva; indeed, it often disappears when ingesting food or liquids. ENT examination is clear and normal laryngeal mobility can be felt when gently rocking the larynx across the postcricoid tissues. A contrast swallow will not only show the structures below the pharynx but also assess the swallowing dynamically. Treatment is with explanation and reassurance. Antidepressants may be tried. Any suspicious area will require an endoscopy with biopsy.

Disorders of the Eye

Most of the major and common types of eye disease are covered below. However, diabetic eye disease (pp. 1265–1269) and hypertensive eye disease (p. 1046) are discussed elsewhere.

Applied Anatomy and Physiology

The average length of the human eye is 24 mm. It is essentially made up of two segments:

• The smaller anterior segment is transparent and coated by the cornea; its radius is approximately 8 mm.

• The larger posterior segment is coated by the opaque sclera; its radius is approximately 12 mm.

It is the cornea and the sclera that give the mechanical strength and shape to the exposed surface of the eye.

The cornea occupies the central aspect of the globe and is one of the most richly innervated tissues in the body. This clear, transparent, avascular structure, measuring 12 mm horizontally and 11 mm vertically, provides 78% of the focusing power of the eye. The eyelids prevent the cornea from drying and becoming an irregular surface by distributing the tear film over the surface of the globe with each blink.

Anatomically, the cornea is made up of five layers:

• epithelium

• Bowman's layer (membrane)

• stroma

• Descemet's membrane

• endothelium.

The endothelial cells lining the inner surface of the cornea are responsible for maintaining the clarity of the cornea by continuously pumping fluid out of the tissue. Any factor that alters the function of these cells will result in corneal oedema and cause blurred vision.

The sclera is an opaque white structure covering four-fifths of the globe and is continuous with the cornea at the limbus. The six extraocular muscles responsible for eye movements are attached to the sclera, and the optic nerve perforates it posteriorly.

The conjunctiva covers the anterior surface of the sclera. This richly vascularized and innervated mucous membrane stretches from the limbus over the anterior sclera (where it is called the bulbar conjunctiva) and is then reflected on to the undersurface of the upper and lower lids (the tarsal conjunctiva). The area of conjunctival reflection under the lids makes up the upper and lower fornix.

The anterior chamber is the space between the cornea and the iris, and is filled with aqueous humour (Fig. 30.19). This fluid is produced by the ciliary body (2 µL/min) and provides nutrients and oxygen to the avascular cornea. The outflow of aqueous humour is through the trabecular meshwork and canal of Schlemm adjacent to the limbus. Any factor that impedes its outflow will increase the intraocular pressure. The upper range of normal for intraocular pressure is 21 mmHg.

Figure 30.19 Cross-section of the eyeball.

The uveal tract is made up of the iris anteriorly, the ciliary body and the choroid. The iris is the coloured part of the eye under the transparent cornea. The muscles of the iris diaphragm regulate the size of the pupil, thereby controlling the amount of light entering the eye. The muscles of the ciliary body control the accommodation of the lens, and the secretory epithelium produces the aqueous humour (see above). The highly vascular choroid lines the inner aspect of the sclera and upon this lies the retina.

The lens lies immediately posterior to the pupil and anterior to the vitreous humour. It is a transparent biconvex structure and is responsible for 22% of the refractive power of the eye. By changing its shape, it can alter its refractive power and help to focus objects at different distances from the eye. By the fourth decade of life, this ability to change shape starts to decline and, with time, the lens starts to become less transparent and cataracts begin to develop.

The vitreous humour fills the cavity between the retina and the lens.

The retina is a multilayered structure. The metabolically active region of the retina is represented in Figure 30.20. There are two types of photoreceptors in the retina: rods and cones. There are approximately 6 million cones, mainly confined to the macula, and these are responsible for detailed central vision and colour vision. The peripheral retina has around 125 million rods that are responsible for peripheral vision. The axons of the ganglion cells form the optic nerve (or disc) of the eye (Fig. 30.21).

Figure 30.20 Schematic diagram of the retina.

Figure 30.21 Fundus photograph of the left eye.

The blood supply to the eye is via the ophthalmic artery; in particular, the central retinal artery is responsible for supplying the inner retinal layers. Venous return is through the central retinal and ophthalmic veins. Local lymphatic drainage is to the pre-auricular and submental nodes.

The sensory innervation of the eye is through the trigeminal (Vth) nerve. The six extraocular muscles are supplied by different nerves (see pp. 805–806):

• oculomotor (IIIrd) nerve: medial, superior, inferior rectus and inferior oblique

• trochlear (IVth) nerve: superior oblique

• abducens (VIth) nerve: lateral rectus.

The oculomotor (IIIrd) nerve also supplies the upper lid and, indirectly, the pupil (parasympathetic fibres are attached to it). The facial (VIIth) nerve supplies the orbicularis and other muscles of facial expression.

Clinical Approach to the Patient with a Disorder of the Eye

History and examination

A detailed history gives most of the facts needed to make a working diagnosis. The eye has limited mechanisms by which it can convey a diseased state. Common symptoms include alteration in visual acuity, redness, pain, discharge and photophobia.

It is essential to adopt a systematic approach to the examination of the eye. Different approaches and instruments (including direct ophthalmoscope, slit lamp with or without Goldman or Volk lens) are necessary for examination of the lids and anterior and posterior segments, as well as extraocular movements.

Visual acuity

It is vital for an accurate assessment of visual acuity to be recorded in all people with an eye problem. The visual acuity of each eye is recorded in two ways: distance visual acuity and near visual acuity. Distance vision is measured in Snellen letters or, ever more commonly, in LogMAR letters or figures of different sizes (see below). The recording is given as an expression of the line of letters that can be discerned at a particular distance, usually 6 metres (20 feet): for example 6/60, where 6 equals the distance of the chart from the eye in metres and 60 equals the distance at which the letter subtends 5′ at the nodal point.

The Snellen visual acuity chart (Fig. 30.22) is most commonly employed, but use of the LogMAR chart (logarithm of the Minimum Angle of Resolution; Fig. 30.23) is increasing, largely due to its necessity in studies or research, since it allows better statistical analysis of results. Unlike the Snellen and other visual acuity charts, the LogMAR chart has equal graduation between the letters on a line, as well as the space between lines. There is also a fixed number of letters – five – on each line. Research conducted using a logarithmic progression in size of letters on a test chart provides the most accurate visual acuity measurement. Snellen equivalents can be calculated from the LogMAR charts if necessary (Fig. 30.24).

Figure 30.23 LogMAR chart (logarithm of the Minimum Angle of Resolution).

Figure 30.24 Snellen equivalents can be calculated from the LogMAR charts if necessary. Vision is often recorded at 4 metres in studies, and logMAR equivalents or decimals are used in statistics.

Common Disorders of the Eye

Refractive errors

The eye projects a sharp and focused image on to the retina. Refractive errors refer to any abnormality in the focusing mechanism of the eye and not to any opacity in the system, such as a corneal or retinal scar.

The refraction of light in emmetropic (normal), myopic (short-sighted; negative lenses will correct) and hypermetropic (long-sighted; positive lenses will correct) eyes is shown in Figure 30.25.

Figure 30.25 Refraction. A. Emmetropic (normal). B. Myopic (short-sighted). C. Hypermetropic (long-sighted).

Astigmatism is a refractive error of the eye in which there is a different degree of refraction in the different meridians of curvature. It may be myopic in one plane and hypermetropic or emmetropic in the other plane. In this situation, the front surface of the eye is shaped more like a rugby ball than a football.

Presbyopia is the term used to describe the normal ageing of the lens, which leads to a change in the refractive state of the eye. As the lens ages, it becomes less able to alter its curvature and this causes difficulty with near vision, especially reading.

Management

Errors of refraction can be corrected by using spectacles or contact lenses. The latter often result in better-quality vision but carry the risk of infection. They may be the only option in some refractive states such as keratoconus, a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and to take on a more conical shape than its normal gradual curve. A number of surgical techniques can correct these errors of refraction, with varying degrees of accuracy. Phakic intraocular lenses may be used to treat high degrees of myopia but the most popular method remains the excimer laser to re-profile the corneal curvature (using PRK, LASIK and LASEK techniques). The laser either removes corneal tissue centrally to flatten the cornea in myopia or it removes tissue from the peripheral cornea to steepen it in hypermetropia.

Disorders of the lids

The lids afford protection to the eyes and help to distribute the tear film over the front surface of the globe. Excess tears are drained via the puncta and lacrimal system to the nose (Fig. 30.26). Malposition of the lids, factors that affect blinking and lacrimal drainage can all cause problems.

Entropion

The lid margin rolls inwards so that the lashes are against the globe (Fig. 30.27A). The lashes act as a foreign body and cause irritation, leading to a red eye that can mimic conjunctivitis. Occasionally, the constant rubbing of lashes against the cornea causes an abrasion. The most common cause is ageing and surgery is usually required.

Ectropion

The lid margin rolls outwards and is not apposed to the globe. As a result, the lacrimal punctum is not in the correct anatomical position to drain tears and patients usually complain of a watery eye. Underlying factors include age, VIIth nerve palsy and cicatricial skin conditions. Surgery is usually required.

Dacryocystitis

Patients who have inflammation of the lacrimal sac usually present with a painful lump at the side of the nose adjacent to the lower lid (Fig. 30.27B). This should be treated with oral broad-spectrum antibiotics such as a cephalosporin, and patients should be watched carefully for signs of cellulitis. All patients should be referred to the ophthalmologist, as some have an underlying mucocele or dilated sac, and will require surgery.

Blepharitis

This is an extremely common condition in which inflammation of the lid margins may involve the lashes and lash follicles (Fig. 30.28A), resulting in styes, or inflammation and blockage of meibomian glands (Fig. 30.28B) leading to chalazion (Fig. 30.28C). Common underlying causes of blepharitis include meibomian gland dysfunction, seborrhoea and Staphylococcus aureus infection. Patients can be asymptomatic or complain of itchy, burning eyes because of tear film instability resulting from meibomian gland dysfunction. Staph. aureus is frequently responsible for chronic blepharo-conjunctivitis and some patients may develop keratitis in the cornea (Fig. 30.29).

Management

Lid hygiene is the mainstay of treatment for blepharitis, as it helps to reduce the bacterial load and unblock meibomian glands. A short course of topical chloramphenicol or fusidic acid is useful in chronic cases, but in severe cases or cases where acne rosacea is suspected, oral doxycycline is used. Some patients are left with a lump once the acute inflammatory phase has subsided. Most of these patients find the lump, or chalazion, cosmetically unacceptable and require incision and curettage. People with keratitis should be referred to the ophthalmologist for topical steroids.

Conjunctivitis

The most common cause of a red eye, inflammation of the conjunctiva can arise from a number of causes, viral, bacterial and allergic being the most frequently encountered. Common features in all types include soreness, redness and discharge; in general, the visual acuity is good. History should include the speed of onset of the inflammation, the colour and consistency of the discharge, whether the eye is itchy, and if there has been a recent history of a cold or sore throat. In the neonate, it is vital to exclude gonococcal or chlamydial conjunctivitis associated with maternal sexually transmitted infection. The differential diagnosis of conjunctivitis is shown in Box 30.8.

Box 30.8

Conjunctivitis

Type	Discharge	Pre-auricular node	Corneal involvement	Comment
Bacterial	Mucopurulent	−ve (except gonococci)	+ve Gonococcus	Rapid onset
Viral	Watery	+ve	+ve Adenovirus	Cold and/or sore throat
Chlamydial	Watery	+ve	+ve	Genitourinary discharge
Allergic	Stringy	−ve	+ve	Itchiness

Bacterial conjunctivitis

Bacterial conjunctivitis is uncommon, making up 5% of all cases of conjunctivitis. In the vast majority of patients, it causes a sore or gritty eye in the presence of good vision. Bacterial conjunctivitis is invariably bilateral and should be suspected when conjunctival inflammation is associated with a purulent discharge.

Clinical features

Gonococcal conjunctivitis should be suspected when the onset of symptoms is rapid, the discharge is copious, and ocular inflammation includes chemosis (conjunctival oedema) and lid oedema. Gonococci are a cause of conjunctivitis, giving rise to a palpable pre-auricular node. Less acute or subacute purulent conjunctivitis with moderate discharge can be attributed to organisms such as Haemophilus influenzae and Streptococcus pneumoniae. Chronic conjunctivitis is usually associated with mild conjunctival injection and scant purulent discharge. Common organisms include Staphylococcus aureus and Moraxella lacunata.

Management

Prompt treatment with oral and topical penicillin is given in gonococcal conjunctivitis to ensure a reduced rate of corneal perforation. A Gram stain of the conjunctival swab can quickly confirm the presence of diplococci. Gonococcal conjunctivitis is a notifiable disease in the UK. Empirical treatment for both subacute and chronic conjunctivitis involves a topical broad-spectrum antibiotic, such as chloramphenicol. Swabs should be taken if these cases do not respond to this initial treatment. Antibiotic resistance is increasing.

Chlamydial conjunctivitis

Chlamydia trachomatis (see pp. 321–322) in developed countries causes a sexually transmitted infection that is most prevalent in sexually active adolescents and young adults. Direct or indirect contact with genital secretions is the usual route of infections but shared eye cosmetics can also be involved. Neonatal chlamydial conjunctivitis is a notifiable disease in the UK and should be suspected in newborns with a red eye. Mothers should be asked about sexually transmitted infections.

Clinical features

The onset of symptoms is slow, and patients may complain of mild discomfort for weeks. In these cases, the red eye is associated with a scanty mucopurulent discharge and a palpable pre-auricular lymph node. In chronic cases, it is not unusual to see superior corneal vascularization. In neonates, the onset of the red eye is typically around 2 weeks after birth, whereas gonococcal conjunctivitis occurs within days of birth. Conjunctival swabs should be taken and a nucleic acid amplification test (NAAT; see p. 321) performed prior to commencement of treatment.

Management

Topical erythromycin twice daily is commenced and patients referred to the genitourinary physician. Neonates should be started on topical erythromycin and referred to the paediatrician, as there may be associated otitis media or pneumonitis.

Trachoma

See Box 30.9.

Box 30.9

Trachoma

• A very common cause of blindness worldwide (see p. 288)

• Found mainly in the tropics and the Middle East

• Caused by Chlamydia trachomatis but not usually sexually transmitted

• Chronic conjunctival inflammation causes progressive scarring, trichiasis, entropion and subsequent corneal scarring

• The result may be severe visual impairment or blindness from corneal opacification or ulceration

Viral conjunctivitis

Adenoviral conjunctivitis

This is highly contagious and can cause epidemics in communities. Transmission is through direct or indirect contact with infected individuals. The onset of symptoms may be preceded by a cold or influenza-like symptoms. Inflammation is commonly associated with chemosis, lid oedema and a palpable pre-auricular lymph node. Some patients develop a membrane on the tarsal conjunctiva (Fig. 30.30) and haemorrhage on the bulbar conjunctiva. Viral conjunctivitis can cause deterioration in visual acuity owing to corneal involvement (focal areas of inflammation). In 50% of these patients, the conjunctivitis is unilateral.

Figure 30.30 Viral conjunctivitis. A. Conjunctival chemosis. B. Pseudomembrane on lower lid.

The condition is largely self-limiting in the majority of cases. Lubricants, together with a cold compress, can be a soothing element of management for patients. Adhering to strict hygiene and keeping towels separate from those of the rest of the household go a long way towards reducing the spread of the infection. In people with corneal involvement or intense conjunctival inflammation, topical steroids are indicated.

Herpes simplex conjunctivitis

Primary ocular herpes simplex conjunctivitis is typically unilateral. It usually causes a palpable pre-auricular lymph node, and cutaneous vesicles develop on the eyelids and the skin around the eyes in the majority. Over 50% of these patients develop a dendritic corneal ulcer (Fig. 30.31). The organism responsible for this condition is the herpes simplex virus (HSV), usually HSV-1, although HSV-2 can give rise to ocular infection.

Figure 30.31 Dendritic ulcers on the cornea. A. Stained with fluorescein. B. Stained with fluorescein and viewed with blue light.

Primary ocular HSV infection is self-limiting but most clinicians choose treatment with topical aciclovir in order to limit the risk of corneal epithelial involvement.

Molluscum contagiosum conjunctivitis

This is typically unilateral; it produces a red eye that generally goes unrecognized and comes to the forefront because patients fail to improve and the cornea starts to become involved. On close inspection, pearly, umbilicated nodules, filled with the DNA poxvirus, can be seen on the lid margin.

Management includes curetting the central portion of the lesion, freezing the centre or completely excising the lesion. If the corneal involvement is severe or the eye is very inflamed, a short course of topical steroids, such as prednisolone 0.5% or dexamethasone 0.1%, is helpful.

Phthiriasis palpebrarum

Phthiriasis palpebrarum (Fig. 30.32) is an eyelid infestation caused by Phthirus pubis, or the crab louse. Infestation of the cilia and eyelid is rare. It leads to blepharitis with marked conjunctival inflammation, pre-auricular lymphadenopathy and, rarely, secondary infection at the site of louse bite.

Management

Mechanical removal of the lice with fine forceps, physostigmine 1.25% and pilocarpine gel 4% are all effective treatments.

Allergic conjunctivitis

There are five main types of allergic conjunctivitis: seasonal, perennial, vernal, atopic and giant papillary. Both seasonal and perennial allergic conjunctivitis are acute allergic conjunctival disorders. Symptoms include itching and pink to reddish eyes. These two eye conditions are mediated by mast cells and can be treated easily with cold compresses, eye washes with tear substitutes, and avoidance of allergens. The last three are difficult to treat; they are chronic and can be sight-threatening, so should be referred to an ophthalmologist.

Seasonal/perennial conjunctivitis

Seasonal allergic conjunctivitis and perennial conjunctivitis, affecting 20% of the general population in the UK, are allergic reactions to grass and tree pollen and fungal spores. Seasonal allergic conjunctivitis occurs mainly in spring and summer. Perennial allergic conjunctivitis occurs all year round but peaks in the autumn; causes include allergens, such as house-dust mites.

The main symptoms include itching, redness, soreness, watering and a stringy discharge. Occasionally, the conjunctiva may become so hyperaemic that chemosis results. This is usually associated with swollen lids.

Lowering the allergen load (reducing dust; see p. 1077) is helpful. Medical treatment includes the use of antihistamine drops such as azelastine and emedastine, together with topical mast-cell-stabilizing agents such as sodium cromoglicate and nedocromil. Olopatadine (twice daily) has dual action and is very effective. Corticosteroid drops should be avoided. Oral antihistamines help the itching.

Corneal disorders

Trauma

Corneal abrasions

Trauma resulting in the removal of a focal area of epithelium on the cornea is very common. Abrasions usually occur when the eye is accidentally poked with a finger, a foreign body flies into the eye or something brushes against the eye.

Symptoms include severe pain, due to exposure of the corneal nerve endings, lacrimation and inability to open the eye (blepharospasm). Blinking and eye movement can aggravate the pain and foreign body sensation. The visual acuity is usually reduced. Most cases will need topical anaesthetic drops such as oxybuprocaine or tetracaine to be administered before it is possible to examine the eye. The cornea should be inspected with a blue light after instillation of fluorescein drops. The orange dye will stain the area of the abrasion. Under blue light, the abrasion lights up as green. Occasionally, foreign bodies can lodge on the undersurface of the upper lid and give rise to linear vertical abrasions. Eversion of the upper lid is necessary in all cases of abrasions (Fig. 30.33).

Figure 30.33 Linear corneal abrasion. A. Stained with fluorescein. B. Stained with fluorescein and viewed with blue light.

Treatment consists of a broad-spectrum topical antibiotic, such as chloramphenicol drops or ointment four times a day for 5 days. The role of padding is controversial but common practice is to pad the affected eye for 24 hours once chloramphenicol ointment has been applied to the eye.

Corneal foreign body

Occasionally, when something flies into the eye, it sticks on the cornea (Fig. 30.34A). It may be associated with lacrimation and photophobia. Examination is best attempted following instillation of a topical anaesthetic and should include eversion of the upper lid (Fig. 30.34B). Corneal foreign bodies can usually be seen directly with a white light.

Figure 30.34 Foreign bodies (arrowed). A. Corneal. B. Subtarsal.

The corneal foreign body should be removed. Treatment involves a topical antibiotic, such as chloramphenicol four times a day for 5 days, or fusidic acid twice a day for 5 days.

High-velocity trauma

In cases of high-velocity trauma, corneal perforation or an intraocular foreign body should be suspected. Examination may show a corneal laceration and a foreign body may also be embedded in the cornea. The foreign body may be present on the iris or in the lens or vitreous. Other clues pointing towards a penetrating injury include a large subconjunctival haemorrhage, a flat anterior chamber with low intraocular pressure, and the presence of blood in the anterior chamber (hyphaema). Urgent referral to the ophthalmologist is mandatory, ensuring that no drops are instilled into the eye and that a plastic shield is placed over the eye to minimize further risk of trauma.

Blunt trauma usually results in periorbital bruising and gross lid oedema, which can make examination to exclude perforating injury difficult. These patients should be referred to the ophthalmologist for a detailed ocular examination to exclude a perforation, retinal detachment or a traumatic hyphaema (Fig. 30.35).

Figure 30.35 Blunt trauma. Hyphaema and globe rupture with iris prolapse.

Keratitis

This is a general term used to describe corneal inflammation. Common causes include herpes simplex virus, contact lens-associated infection and blepharitis. Symptoms include the sensation of a foreign body or pain (depending on the size and depth of the ulcer), photophobia and lacrimation. Vision is reduced if the ulcer affects the visual axis.

Herpes simplex keratitis

Corneal epithelial cells infected with the virus eventually undergo lysis and form an ulcer, which is typically dendritic in shape (see Fig. 30.31). The ulcer stains with fluorescein and can be observed easily with a blue light. Topical immunosuppression, such as with steroid drops, or systemic immunosuppression, such as in AIDS, can lead to the centrifugal spread of the virus, such that the ulcer increases in area and is referred to as a geographic ulcer. Recurrent attacks of HSV keratitis can be triggered by ultraviolet light, stress and menstruation. All these factors are responsible for activating the virus, which normally lies dormant in the ganglion of the Vth nerve.

Treatment consists of aciclovir ointment five times a day for 2 weeks; this is usually very effective.

Contact lens-related keratitis

A small number of contact lens wearers develop infective corneal ulcers, which are potentially sight-threatening (Fig. 30.36). The organisms usually responsible include Gram-positive and Gram-negative bacteria. Patients should be referred to an ophthalmologist for scraping of the ulcer and commencement of antibiotic treatment.

Keratoconus

Keratoconus is an eye condition in which the normally round, dome-shaped cornea progressively thins and causes a cone-shaped bulge to develop. Aetiology is uncertain but genetic factors play a role, and the condition is more common in people with allergic diseases such as asthma, in Down syndrome and in some disorders of collagen such as Marfan's disease. Keratoconus affects up to 1 in 1000 people and is more common in individuals of Asian heritage. It is usually diagnosed in teenagers and young people.

Management

In the early stages, spectacles or soft contact lenses may be used to correct vision. As the cornea becomes thinner and steeper, rigid gas-permeable contact lenses may be necessary.

Corneal cross-linking is a new treatment that can stop keratoconus becoming worse. It is effective in more than 9 out of 10 patients, with a single 30-minute day-case procedure, but is only suitable when the corneal shape is continuing to deteriorate. In very advanced cases, where contact lenses fail to improve vision, a corneal transplant may be needed. 

Corneal dystrophy

Corneal dystrophies may be classified anatomically as consisting of:

• epithelial and subepithelial dystrophies

• epithelial–stromal TGFBI corneal dystrophies

• stromal dystrophies

• endothelial dystrophies.

The most common endothelial dystrophy, Fuchs' corneal dystrophy, is a genetically associated degenerative disorder leading to corneal oedema and vision loss. The gene involved is TCF4. The condition affects both eyes; it is more common in females and is of gradual onset, leading to blindness in the 40–60 age group. There is an accumulation of deposits (guttae) in the cornea with thickening of Descemet's membrane. Treatment is by corneal transplantation.

Cataracts

Cataract (Fig. 30.37) is by far the most common cause of preventable blindness in the world, having an effective surgical treatment. In the UK, approximately 250 000 cataract operations are performed each year, making it the most common surgical procedure.

Aetiology

In young patients, familial or congenital causes should be excluded. Any history of ocular inflammation is noted. Cataracts diagnosed in infants demand urgent referral to the ophthalmologist in order to minimize the subsequent development of amblyopia.

Clinical features

Gradual painless deterioration of vision is the most common symptom. Other symptoms are dependent on the type of cataract: for example, a posterior capsular type would lead to glare and problems with night driving. Early changes in the lens are correctable by spectacles but eventually the opacification needs surgical intervention.

Investigations

Blood glucose, serum calcium and liver biochemistry should be measured to diagnose metabolic disorders.

Management

Small-incision extracapsular or phacoemulsification cataract extraction with the insertion of an intraocular lens is the treatment of choice (Fig. 30.37C). Recent advances have enabled surgeons to perform multiple steps in the surgical process with the Excimer laser to enhance visual outcomes. Lens technology has also improved and Toric lenses are available to treat astigmatism, and multifocal or accommodative lenses to overcome intraocular lens-induced presbyopia.

Glaucoma

Glaucoma is due to increased pressure inside the eye, which is sufficiently elevated to cause optic nerve damage and result in visual field defects, with loss of sight (Fig. 30.38). Normal intraocular pressure (IOP) is 10–21 mmHg. Some types of glaucoma can result in an IOP exceeding 70 mmHg. Glaucoma is the second most common cause of blindness worldwide and the third most common cause of blind registration in the UK.

Primary open-angle glaucoma

Primary open-angle glaucoma (POAG) is the most common form of glaucoma. High intraocular pressures result from reduced outflow of aqueous humour through the trabecular meshwork (Fig. 30.39A). Common risk factors include age (0.02% of 40-year-olds versus 10% of 80-year-olds), race (black Africans are at five times greater risk than whites), positive family history and myopia.

Clinical features

POAG causes a gradual, insidious, painless loss of peripheral visual field, causing loss of vision. It is initially asymptomatic and the central vision remains good until the end-stage of the disease. Usually, glaucoma is identified during a routine ophthalmic examination. Diagnosis is only made if the IOP is measured. The optic disc is inspected and shows an enlarged cup with a thin neuroretinal rim. Visual fields are assessed and show a normal blind spot with scotomas.

Management

Treatment aims to reduce the IOP, either by reducing aqueous production or by increasing aqueous drainage:

• Beta-blockers, such as timolol, carteolol and levobunolol, reduce aqueous production and are the most commonly prescribed topical agents. These drugs are contraindicated in people with chronic obstructive pulmonary disease, asthma or heart block.

• Prostaglandin analogues, such as latanoprost, bimatoprost and travoprost, increase aqueous outflow and are also used (alone or in combination with beta-blockers) for POAG, as they can reduce IOP by 30%.

• Carbonic anhydrase inhibitors, such as dorzolamide and acetazolamide, reduce aqueous production and are available in topical preparations. Acetazolamide is also available orally and, in this form, is the most potent drug for reducing IOP. It should not be used in patients who have a sulphonamide allergy.

• Selective laser trabeculoplasty (SLT) is a form of laser surgery that can lower the IOP by about 30% when used as initial therapy. It is useful when eye-drop medications are not lowering the eye pressure enough or are causing significant side-effects. It may sometimes be used as initial treatment in glaucoma, although effects commonly last 1–5 years only.

Acute angle-closure glaucoma

Acute angle-closure glaucoma (AACG) is an ophthalmic emergency. There is a sudden rise in intraocular pressure to levels over 50 mmHg. This occurs due to reduced aqueous drainage when the ageing lens pushes the iris forwards against the trabecular meshwork (Fig. 30.39B). People most at risk of developing AACG are those with shallow anterior chambers, such as hypermetropes and women. The attack is more likely to occur under reduced light conditions when the pupil is dilated.

Clinical features

AACG causes sudden onset of a red, painful eye and blurred vision. Patients become unwell, with nausea and vomiting, and complain of headache and severe ocular pain. The eye is injected and tender, and feels hard. The cornea is hazy and the pupil is semi-dilated (Fig. 30.40). Box 30.11 shows the differential diagnosis of the acute red eye. Box 30.12 shows features that require urgent referral to an ophthalmologist.

Figure 30.40 Acute angle-closure glaucoma.

Box 30.11

Differential diagnosis of the acute red eye

Cause	Conjunctival injection	Unilateral or bilateral	Pain	Photophobia	Vision	Pupil	Intraocular pressure
Conjunctivitis	Diffuse	Bilateral (often unilateral initially)	Gritty	Occasionally with adenovirus	Normal	Normal	Normal
Keratitis	Diffuse	Unilateral	Gritty	Yes	Reduced	Normal	Normal
Anterior uveitis	Circumcorneal	Unilateral	Painful	Yes	Reduced	Constricted	Normal or raised
Acute glaucoma	Diffuse	Unilateral	Severe pain	Mild	Reduced	Mid-dilated	Raised

Management

Prompt treatment is required to preserve sight and includes:

• i.v. acetazolamide 500 mg (provided there are no contraindications) to reduce IOP, and

• instillation of pilocarpine 4% drops to constrict the pupil to improve aqueous outflow and prevent iris adhesion to the trabecular meshwork.

Other topical drops, such as beta-blockers and prostaglandin analogues, can also be instilled if available, provided there are no contraindications. Analgesia and antiemetics are given as required.

Patients must be referred to an ophthalmologist immediately so that reduction in IOP can be monitored and other agents, such as oral glycerol or i.v. mannitol, can be administered to non-responding patients. Definitive treatment involves making a hole in the periphery of the iris of both eyes either by laser or by surgical means.

Uveitis

Uveitis is inflammation of the uveal tract, which includes the iris, ciliary body and choroid. It is classified according to the part of the uveal tract that the inflammation affects:

• Anterior uveitis is inflammation that affects the anterior part of the uveal tract. This can include the iris (iritis), or both the iris and the ciliary body (iridocyclitis). It is the most common type of uveitis.

• Intermediate uveitis is inflammation that affects the middle part of the uveal tract or eye, mainly the vitreous. It can also affect the underlying retina.

• Posterior uveitis is inflammation that affects the posterior part of the eye. It can affect the choroid, optic nerve head and the retina (or any combination of these structures). It includes chorioretinitis, retinitis and neuroretinitis.

• Panuveitis is inflammation affecting the whole of the uveal tract.

The most common symptoms of uveitis are blurred vision, pain, redness, photophobia and floaters. Each symptom is determined by the location of the inflammation, such that photophobia and pain are common features of iritis whilst floaters are commonly seen with posterior uveitis.

Anterior uveitis (iritis)

The classic presentation entails a triad of eye symptoms: redness, pain and photophobia. Vision can be normal or blurred, depending on the degree of inflammation. The eye can be generally red or the injection can be localized to the limbus. The anterior chamber shows features consistent with inflammation, including cells, keratic precipitates on the corneal endothelium, fibrin or hypopyon (pus), and the pupil may have adhered to the lens (posterior synechiae) (Fig. 30.41). The IOP may be normal or raised, either due to cells clogging up the trabecular meshwork, or due to posterior synechiae causing aqueous humour to build up behind the iris and force the iris against the trabecular meshwork and so reduce aqueous drainage.

Figure 30.41 Anterior uveitis. A. Acute uveitis with hypopyon. B. Keratic precipitates (arrowed) on the corneal endothelium.

Management

This consists of reducing inflammation with the use of topical steroids such as dexamethasone 0.1% and dilating the pupil with cyclopentolate 1% to prevent formation of posterior synechiae. Dilatation also allows fundoscopy to exclude posterior segment involvement. If the IOP is raised, this is treated with topical beta-blockers, prostaglandin analogues, or oral or i.v. acetazolamide. Referral should be made to the ophthalmologist.

Intermediate uveitis

This usually causes painless blurred vision, most commonly associated with floaters. It is unusual to experience photophobia and redness. Both eyes are commonly affected in intermediate uveitis.

Management

This consists of a combination of treatment for anterior and posterior uveitis depending on the degree of anterior and posterior involvement.

Posterior uveitis

This commonly causes painless, blurred vision and can progress to severe visual loss. It is commonly associated with floaters and scotomata, or blind spots in the visual field.

Posterior uveitis is often found with systemic autoimmune diseases or infections; appropriate investigations should be performed and treatment given that is aimed at the cause.

Autoimmune diseases associated with uveitis include rheumatoid arthritis and Behçet's disease, ankylosing spondylitis and positive HLA-B27 (see p. 683), reactive arthritis, sarcoidosis, psoriasis and inflammatory bowel disease (Crohn's disease and ulcerative colitis; see p. 407). Infections, a rare cause of uveitis, include herpes simplex, herpes zoster, toxoplasmosis, cytomegalovirus, syphilis, tuberculosis, HIV infection and Lyme disease. In a number of patients, no cause is found (idiopathic uveitis).

Management

Steroids are commonly given orally, or more locally by injection into or around the eye. If steroid treatment is needed to treat uveitis in the longer term, second-line immunosuppressive drugs, such as mycophenolate mofetil, ciclosporin or azathioprine, are used. Biological agents, such as rituximab or adalimumab, are showing increasing promise in more severe cases.

Disorders of the retina

Central retinal vein occlusion

Central retinal vein occlusion (CRVO) usually leads to profound, sudden, painless loss of vision with thrombosis of the central retinal vein at or posterior to the lamina cribrosa, where the optic nerve exits the globe. The thrombus causes obstruction to the outflow of blood, leading to a rise in intravascular pressure. This results in dilated veins, retinal haemorrhage, cotton wool spots and abnormal leakage of fluid from vessels, causing retinal oedema (Fig. 30.42). In severe cases, an afferent papillary defect (p. 804) is present and this suggests the ischaemic variant.

Predisposing factors include increasing age, hypertension and cardiovascular disease, diabetes, glaucoma and, in the younger age group, blood dyscrasias and vasculitis.

Management

Treatment of any underlying medical condition is mandatory. Referral to an ophthalmologist is essential to monitor the eye, as some patients can develop retinal ischaemia with resulting neovascularization of the retina and iris. Panretinal photocoagulation should be commenced if there is neovascularization, and intravitreal steroid or anti-vascular endothelial growth factor (anti-VEGF) therapy is also used if there is macular oedema. Patients who develop iris neovascularization – rubeosis – where these new blood vessels block the drainage angle are at risk of developing rubeotic glaucoma.

Central retinal artery occlusion

Central retinal artery occlusion (CRAO) results in sudden, painless severe loss of vision. Retinal arterial occlusion results in infarction of the inner two-thirds of the retina. The arteries become narrow and the retina becomes opaque and oedematous. A cherry-red spot is seen at the fovea because the choroidal vasculature shows up through the thinnest part of the retina (Fig. 30.43). An afferent papillary defect is usually present.

Arteriosclerosis-related thrombosis is the most common cause of CRAO. Emboli from atheromas and diseased heart valves are other causes. Giant cell arteritis (see pp. 700–701) must be excluded.

Management

CRAO is an ophthalmic emergency since studies have shown that irreversible retinal damage occurs within 90 minutes of onset. Ocular massage and 500 mg i.v. acetazolamide help to reduce ocular pressure and may assist in dislodging the emboli. Breathing into a paper bag allows a build-up of carbon dioxide, which acts as a vasodilator and so helps dislodge the emboli. Other options include making a corneal paracentesis to drain off some aqueous humour, thereby reducing the IOP.

People with CRAO should have a thorough medical evaluation to determine the aetiology of the emboli or thrombus. Some patients may present with transient loss of vision or amaurosis fugax (see p. 832). All people with CRAO and amaurosis fugax should be started on oral aspirin if it is not medically contraindicated.

Retinal detachment

This causes a painless, progressive visual field loss. The shadow corresponds to the area of detached retina. If the detachment affects the macula, central vision will be lost. Following a tear in the retina, fluid collects in the potential space between the sensory retina and the pigment epithelium (Fig. 30.44). Patients usually report a sudden onset of floaters, often associated with flashes of light (photopsia) prior to the detachment. These individuals should be referred to an ophthalmologist for a detailed fundal examination.

Figure 30.44 Retinal tear leading to detachment.

Retinitis pigmentosa

This is a common chronic, inherited, degenerative disease of the retina, which can be primary or part of a syndrome, and leads to blindness. There is constriction of the peripheral vision, leading to tunnel vision and progressive loss of night vision.

Ophthalmoscopy shows bone spicule deposits and attenuated retinal vessels. Several genes are implicated.

There is no treatment but high-dose vitamin A supplementation may slow progression. Gene therapy is being investigated.

Age-related macular degeneration

The cause is unknown but suggested risk factors include increasing age, smoking, hypertension, hypercholesterolaemia and ultraviolet exposure.

There are two types:

• Non-exudative (dry) macular degeneration describes a painless and progressive loss of central vision. With age, lipofuscin deposits (drusen) are found between the retinal pigment epithelium (RPE) and Bruch's membrane (Fig. 30.45A; see Fig. 30.20). Drusen may be hard or soft, and there may be focal RPE detachment. Not all people with these changes will be affected visually but some develop distortion and blurring of their central vision. Extensive atrophy of RPE can occur (geographic atrophy).

• Exudative (wet) AMD (10% of cases) occurs with the development of abnormal subfoveal choroidal neovascularization in the region of the macula and causes severe central visual loss (Fig. 30.45B).

Figure 30.45 Age-related macular degeneration. A. With deposition of material (drusen) over the macula. B. With choroidal neovascularization.

Management

People with central distortion or with frank macular pathology should be referred urgently to the ophthalmologist for assessment of treatment. Anti-VEGF, such as ranibizumab, aflibercept and bevacizumab, are given by intravitreal injections with great success; the last of these is unlicensed yet less expensive. The treatment course should be commenced as a matter of urgency, as vision is maintained in up to 95% of patients and improves in approximately one-third. Initial monthly monitoring with optical coherence tomography (OCT) is recommended (Fig. 30.46). Laser treatment and photodynamic therapy with verteporfin constituted the treatment of choice in the past for wet AMD but now have limited roles.

Figure 30.46 Age-related macular degeneration seen by optical coherence tomography. (a) Area of thickened retina. (b) Pigment epithelial detachment. (c) Subretinal fluid.

Severe visual loss is possible and low-vision aids, such as magnifying glasses, may help to improve a patient's independence.

Visual loss

Every patient with unexplained sudden visual loss requires ophthalmic referral. The initial history and examination are summarized in Box 30.13.

Box 30.13

The initial history and examination in the patient presenting with sudden loss of vision

RAPD, relative afferent papillary defect.

(After Pane A, Simcock P. Practical Ophthalmology. Edinburgh: Churchill Livingstone; 2005.)

The common causes of blindness are similar across the world (Box 30.14). In developing countries, trachoma due to Chlamydia trachomatis (see p. 288) is also a major cause, accounting for 10% of global blindness; onchocerciasis (river blindness, due to Onchocerca volvulus; see p. 309) accounts for blindness in about 1 million people, although this figure is decreasing with treatment. In leprosy, 70% of patients have ocular involvement, and blindness occurs in 5–10% of these. Ocular involvement is common in cerebral malaria (see p. 299), although loss of vision is rare.

HIV infection can produce uveitis but the major problem is severe opportunistic infection of the eye when the CD4 count falls (see pp. 338–339) and anti-retroviral therapy is not available.

Vitamin A deficiency and xerophthalmia affect millions each year; the World Health Organization (WHO) classification of xerophthalmia by ocular signs is shown in Box 10.15.

The WHO lists the most common causes of blindness across the world as cataract, glaucoma, acute macular degeneration, corneal opacity, diabetic retinopathy, and infections from bacteria or parasites.