• Clinical science
  • Physician

Glaucoma

Summary

Glaucoma is a group of eye diseases associated with acute or chronic destruction of the optic nerve with or without concomitant increased intraocular pressure (IOP). In the US, glaucoma is the second leading cause of blindness in adults following age-related macular degeneration (AMD). The two main types are open-angle glaucoma and closed-angle glaucoma. Open-angle glaucoma accounts for 90% of all cases of glaucoma, is slowly progressive, and is initially often asymptomatic, but leads to bilateral peripheral vision loss over time. With appropriate screening (e.g., fundoscopy, gonioscopy, and tonometry) and treatment that lowers IOP (e.g. topical prostaglandins), progression can be stopped before severe damage occurs. Closed-angle glaucoma, on the other hand, is sudden onset and characterized by a painful, red, and hard eye in combination with frontal headache, blurry vision, and halos appearing around lights. Immediate initiation of medical therapy (e.g. timolol eye drops and IV acetazolamide) is crucial to rapidly decrease IOP and prevent vision loss.

Definition

References:[1]

Epidemiology

References:[2][3]

Epidemiological data refers to the US, unless otherwise specified.

Overview

Important types of glaucoma
Open-angle glaucoma Closed-angle glaucoma
Risk factors
Clinical features
  • Initially often asymptomatic
  • Bilateral, progressive visual field loss (from peripheral to central)
  • Sudden onset
    • Unilateral red, hard, and severely painful eye
    • Frontal headaches
    • Vomiting, nausea
    • Steamy cornea and blurred vision
    • Dilated, nonreactive pupil
Treatment
Treatment of glaucoma
Mechanism of IOP decrease Drugs Mechanism of action Adverse effects

↓ Synthesis of acqueous humor

  • No changes in vision or pupil
  • Hypotension
  • Via decrease in cAMP
  • No changes in vision or pupil
Aqueous humor outflow
  • PGF2α
    • Bimatoprost
    • Latanoprost
  • Decreases resistance through uveoscleral flow
  • Darkening of iris
  • Growth of eyelashes

DIrty PARASites PROSper on ALPine BETonies: DIuretics, PARASympathomimetics, PROStaglandins, ALPha agonists, and BETa blockers.

References:[3]

Pathophysiology

Basic physiological principles

References:[4][5]

Open-angle glaucoma

Etiology

Pathophysiology

Clinical features

  • Initially often asymptomatic
  • Over time, nonspecific symptoms such as mild headaches, impaired adaptation to darkness
  • Generally bilateral, progressive visual field loss (from peripheral to central)
  • Halos around lights may occur.

Diagnostics

Therapy

Prevention

  • For all individuals > 40 years, a regular eye examination by an ophthalmologist or optometrist is recommended. This should include:

References:[6][7][8][9][10][11][12]

Closed-angle glaucoma

Etiology/risk factors

Pathophysiology

Clinical features

  • Chronic closed-angle glaucoma
    • Asymptomatic in early stages
    • Progressive vision loss beginning with peripheral fields of vision (due to gradually increasing optic nerve compression)
  • Acute closed-angle glaucoma
    • Sudden onset of symptoms due to an abrupt angle closure
    • Unilaterally inflamed, reddened, and severely painful eye (hard on palpation)
    • Frontal headaches, vomiting, nausea
    • Blurred vision and halos seen around light
    • Cloudy cornea (opacification)
    • Mid-dilated, irregular, unresponsive pupil
    • Complications: rapid permanent vision loss due to ischemia and atrophy of the optic nerve

Acute angle-closure is a medical emergency, as it can cause permanent vision loss if left untreated!

Diagnostics

Do not use mydriatic drugs (e.g., atropine and epinephrine) during ophthalmologic examination in patients with suspected angle-closure glaucoma! Moreover, do not cover the eye, since darkness induces mydriasis and worsens the condition!

Treatment

Blood supply to the optic nerve may be impaired by lowering blood pressure; avoid systemic blood pressure reduction in acute glaucoma patients.

Acute management checklist for acute angle-closure glaucoma [13][14][15][16]

  • Emergency ophthalmology consult
  • Consider indications for emergency pharmacotherapy (e.g., patient with significant visual impairment and no ophthalmologist available within an hour).
    • Initiate immediate pharmacologic therapy: Administer each of the following, given one minute apart from each other: [13]
    • Consider the addition of one of the following hyperosmotic agents if there is no improvement after 60 minutes or if initial IOP > 50 mm Hg: [13][17]
  • Place the patient in a supine position.
  • Supportive care (e.g., antiemetics, pain management)
  • Admit patient or transfer to a hospital with an ophthalmology department capable of performing laser peripheral iridotomy (definitive treatment).

Mydriatic drugs, including those commonly used in eye examinations (e.g., tropicamide), are contraindicated in acute angle-closure glaucoma.

References:[18][19][1][13][20][21]