GLAUCOMA, PRIMARY CLOSED-ANGLE

Nandhini Veeraraghavan, MD, CAQSM, FAAFP

 BASICS

DESCRIPTION

Primary angle closure is classified as:

•  Primary angle-closure suspect (PACS) is greater than 180 degrees of iridotrabecular contact (ITC), normal intraocular pressure (IOP) with no optic nerve damage. Primary angle closure (PAC) is >180 degrees ITC with peripheral anterior synechiae(PAS) or elevated IOP but with no optic neuropathy.

•  Primary angle-closure glaucoma (PACG) is >180-degree ITC with PAS, elevated IOP, and optic neuropathy.

•  Acute angle-closure crisis (AACC) is occluded angle with symptomatic high IOP.

•  Plateau iris configuration is any ITC persisting after a patent laser peripheral iridotomy (LPI) or a plateau iris syndrome which is any ITC persisting after a patent LPI with pressure elevation after dilation.

Geriatric Considerations

Increased risk with age and prior history of cataract, hyperopia, and/or uveitis

Pregnancy Considerations

Medications used may cross the placenta and be excreted into breast milk.

EPIDEMIOLOGY

•  Older age

•  Female sex

•  More likely in Chinese, Vietnamese, Pakistanis, or Inuit descent as compared to African and European ancestry

Prevalence

•  In 2013, it is estimated to have a worldwide prevalence of 20.2 million people with majority (15.5 million) in Asia (1). PACG is not as common in the United States; accounts for 10% of all glaucoma

ETIOLOGY AND PATHOPHYSIOLOGY

•  PAC happens when iris touches the trabecular meshwork at the anterior chamber angle. This is called ITC. ITC causes obstruction of aqueous humor outflow through the trabecular meshwork, which causes elevation in IOP. Prolonged ITC can cause scarring, degradation of trabecular meshwork, and loss of vision (1).

•  Most common underlying mechanism of angle closure is pupillary blockage of the aqueous flow from posterior to anterior chamber. This causes increase in pressure in the posterior chamber as compared to the anterior chamber. The buildup of pressure in the posterior chamber leads to anterior bowing of the iris and closing of the angle (1,2).

•  Other mechanisms include predisposing ocular anatomy, such as plateau iris.

Genetics

First-degree relatives have a 1–12% increased risk in whites, 6 times greater risk in Chinese patients with positive family history

RISK FACTORS

•  Hyperopia

•  Age >50 years

•  Shallow anterior chamber

•  Female gender

•  Family history of angle closure

•  Asian, Chinese, or Inuit descent

•  Short axial length

•  Thick crystalline lens

•  Anterior positioned lens

•  Plateau iris

•  Drugs that can induce angle closure:

–  Adrenergic agonists (albuterol, phenylephrine), anticholinergics (oxybutynin, atropine, botulinum toxin A), antihistamines, antidepressants including selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs), sulfa-based drugs, topiramate, cocaine, ecstasy

GENERAL PREVENTION

•  Routine eye exam with gonioscopy for high-risk populations

•  U.S. Preventive Services Task Force: insufficient evidence to recommend for or against screening adults for glaucoma without visual symptoms (3)[A]

•  Prophylactic laser iridotomy may be considered in patient with PACS for preventing PACG.

COMMONLY ASSOCIATED CONDITIONS

•  Cataract

•  Hyperopia

•  Microphthalmos

•  Systemic hypertension

 DIAGNOSIS

HISTORY

•  Patient may be asymptomatic as in PACS or may have acute symptoms as in AACC.

•  Acute symptoms include

–  Severe eye pain

–  Blurred vision

–  Eye redness

–  Halos around lights/objects

–  Frontal headache

–  Nausea and vomiting, which may lead to erroneous abdominal exploration

•  Patients with PACG can have subacute symptoms (intermittent subacute attacks), compromised peripheral vision, or be asymptomatic.

•  Family history of acute angle-closure glaucoma

•  Obtain history of prescription, over-the-counter, and herbal medications.

•  Precipitating factors (dim light, medicines)

•  Review of symptoms

PHYSICAL EXAM

Includes, but is not limited to, the following in the undilated eye

•  Visual acuity with refractive error (hyperopic eyes especially in older phakic patients)

•  Visual field testing and ocular motility

•  Pupil size and reactivity (mid-dilated, asymmetric or oval, minimally reactive, and may have relative afferent papillary pupillary defect)

•  Slit-lamp biomicroscopy–conjunctival hyperemia (in acute cases),central and peripheral anterior chamber depth narrowing, corneal swelling, iris abnormalities (diffuse and focal iris atrophy, posterior synechiae), lens changes (cataract and glaukomflecken-patchy localized anterior subcapsular lens opacities)

•  Intraocular pressure as measured by applanation tonometry

•  Gonioscopy: visualization of anatomy of the angle of both eyes and to look for ITC and peripheral anterior synechiae

•  Anterior segment imaging with ultrasound (US) biomicroscopy and anterior segment optical coherence tomography (AS-OCT) to understand the angle anatomy

•  Undilated fundus exam (congestion, cupping, atrophy of optic nerve)

DIFFERENTIAL DIAGNOSIS

•  Acute orbital compartment syndrome

•  Traumatic hyphema

•  Conjunctivitis, episcleritis

•  Corneal abrasion

•  Glaucoma, malignant, or neovascular

•  Herpes zoster ophthalmicus

•  Iritis and uveitis

•  Orbital/periorbital infection

•  Vitreous or subconjunctival hemorrhage

•  Tight necktie, causing increased IOP

•  Lens-induced angle closure

DIAGNOSTIC TESTS & INTERPRETATION

Initial Tests (lab, imaging)

US biomicroscopy AS-OCT (1)[C]

Diagnostic Procedures/Other

Careful ophthalmic examination including possible evaluation of fundus and optic nerve head, slit lamp biomicroscopy, gonioscopy, and tonometry (1)[C]

Test Interpretation

•  Narrow or closed anterior angle

•  Corneal stromal and epithelial edema

•  Endothelial cell loss (guttata)

•  Iris stromal necrosis

•  Anterior subcapsular cataract (glaukomflecken)

•  Optic disc congestion, cupping, excavation

•  Optic nerve atrophy

 TREATMENT

GENERAL MEASURES

•  Goals of treatment (1)[C]:

–  Reverse or prevent angle-closure process.

–  Control IOP.

–  Prevent damage to the optic nerve.

•  PACS

–  Majority will not develop PAC or PACG.

–  They may be either observed for development of PAC or be treated with iridotomy (1)[C].

•  PAC and PACG

–  Iridotomy performed using thermal or neodymium-doped yttrium aluminium garnet (Nd:YAG) laser (1)[A]

–  Complications of iridotomy: increased IOP, laser burn to the cornea, lens, or retina; late-onset corneal edema; development of posterior synechiae; hyphema; iritis; and ocular dysphotopsia

•  AACC

–  Initial treatment of AACC is to lower the IOP with medications to relieve the acute symptoms followed by iridotomy as soon as possible (1)[A]. For acute attack: ocular emergency

  Manage nausea and pain.

  Immediate ophthalmology consultation

MEDICATION

•  During acute attack, medical therapy lowers IOP to relieve symptoms and clear corneal edema so that iridotomy can be performed as soon as possible.

•  Medical therapy aims at

–  Reduction of aqueous production and reduction of inflammation with

  Carbonic anhydrase inhibitors (CAI): acetazolamide 10 mg/kg IV or orally. May repeat 250 mg in 4 hours to a maximum of 1 g/day. CAI are contraindicated in sulfa allergy and hepatic insufficiency. Topical carbonic anhydrase inhibitors are not potent enough to break the papillary block.

  Topical β-blockers: timolol 0.5%, levobunolol 0.5%, betaxolol 0.5%, or carteolol 1%

  Topical α₂-agonists: brimonidine 0.2% or apraclonidine 0.5%

–  Withdrawing aqueous from vitreous body and posterior chamber using hyperosmotic agents

  Glycerol 1.0 to 1.5 g/kg orally

  Mannitol 1.0 to 1.5g/kg IV

  Hyperosmotic agent should be used with caution in patient with heart and kidney disease. Glycerol can increase blood sugar level and should not be given to diabetic patients.

–  Pupillary constriction to open the chamber angle: topical pilocarpine 1% or 2% or aceclidine 2%. Miotic therapy is ineffective when IOP is markedly elevated due to sphincter ischemia .They may cause forward rotation of ciliary muscle, increasing the papillary block and worsening the IOP.

•  During acute attack, acetazolamide 500 mg IV is given followed by 500 mg PO. Topical therapy is initiated with 0.5% timolol maleate and 1% apraclonidine drops 1 minute apart. Reduction of inflammation is accomplished with topical steroids 1 to 2 doses. In addition, systemic therapy with mannitol 20% 1.5 to 2 g/kg infused over 30 to 60 minutes or oral glycerol (Osmoglyn) (50%) 6 oz PO may be needed. Also treat pain and nausea with analgesic and antiemetics. About an hour after initiating treatment, two doses of pilocarpine drops administered 15 minutes apart to cause miosis in an attempt to open the angle (2)[C].

•  After corneal edema clears, a peripheral iridotomy is done.

ADDITIONAL THERAPIES

Keep patient supine.

SURGERY/OTHER PROCEDURES

•  Definitive therapy for PAC, PACG, and AACC is Nd:YAG laser iridotomy (1,2)[B].

•  Surgical iridectomy may be performed if cornea is cloudy and laser iridotomy cannot be performed.

•  Corneal indentation with four-mirror gonioscopic lens, cotton-tipped applicator, or muscle hook may be used to break a pupillary block in AACC (1)[C].

•  Effectiveness of phacoemulsification with IOL implantation in PACG is unclear (1), (2)[B]. Other procedures to reduce IOP that have been studied include argon laser peripheral iridoplasty (especially for plateau iris configuration/syndrome), anterior chamber paracentesis, goniosynechialysis, and trabeculectomy.

ADMISSION, INPATIENT, AND NURSING CONSIDERATIONS

•  Patient requires metabolic ± electrolyte and volume status monitoring (with osmotic agents).

•  Facilitate close ophthalmology monitoring.

 ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Schedule an immediate ophthalmologic follow-up.

Patient Monitoring

•  Postsurgical follow-up and routine monitoring after acute attack as per ophthalmologist

•  Half of the fellow eye of patients with AACC will develop AACC within 5 years. Hence, prophylactic LPI should be performed in the fellow eye as soon as possible (1)[B].

PATIENT EDUCATION

•  Advise patient to seek emergency medical attention if experiencing a change in visual acuity, blurred vision, eye pain, or headache.

•  Patients with PACS and no iridotomy, avoid use of decongestants, motion sickness medications, adrenergic agents, antipsychotics, antidepressants, and anticholinergic agents.

•  Correct eyedrop administration technique, including the following:

–  Remove contact lenses before administration and wait 15 minutes before reinserting.

–  Allow at least 5 minutes between administration of multiple ophthalmic products.

•  Patient education materials:

–  Glaucoma Research Foundation: http://www.glaucoma.org

–  National Eye Institute: http://www.nei.nih.gov

PROGNOSIS

•  With timely treatment, most patients do not have permanent vision loss.

•  Prognosis depends on ethnicity, underlying eye disease, and time to treatment.

COMPLICATIONS

•  Chronic corneal edema, corneal fibrosis, and vascularization

•  Iris atrophy

•  Cataract

•  Optic atrophy

•  Malignant glaucoma

•  Central retinal artery/vein occlusion

•  Permanent decrease in visual acuity

•  Repeat episode

•  Fellow (contralateral) eye attack

REFERENCES

1.  American Academy of Ophthalmology. Primary Angle Closure Preferred Practice Pattern. San Francisco, CA: American Academy of Ophthalmology; 2015. http://www.aao.org. Accessed October 27, 2016.

2.  European Glaucoma Society. Terminology and guidelines for glaucoma. 4th ed. Savona, Italy: Dogma; 2014. http://www.eugs.org/eng/EGS_guidelines4.asp. Accessed October 27, 2016.

3.  Moyer VA. Screening for glaucoma: U.S. Preventive Services Task Force Recommendation Statement. Ann Intern Med. 2013;159(7):484–489.

ADDITIONAL READING

•  Gupta D, Chen PP. Glaucoma. Am Fam Physician. 2016;93(8):668–674.

•  Kolko M. Present and new treatment strategies in the management of glaucoma. Open Ophthalmol J. 2015;9:89–100.

 SEE ALSO

Glaucoma, Primary Open-Angle

 CODES

ICD10

•  H40.20X0 Unsp primary angle-closure glaucoma, stage unspecified

•  H40.219 Acute angle-closure glaucoma, unspecified eye

•  H40.2290 Chronic angle-closure glaucoma, unsp eye, stage unspecified

CLINICAL PEARLS

•  Examiner can determine if patient is hyperopic by observing the magnification of the patient’s face through his or her glasses (myopic lenses minify).

•  A careful history may reveal similar episodes of angle closure that resolved spontaneously. Miotics, such as pilocarpine, can be effective during mild attacks but ineffective in the setting of high IOP (due to pressure-induced iris sphincter ischemia).

•  In patient with AACC, the fellow eye should undergo prophylactic laser iridotomy.