Angle-closure: Overview

Angle-closure glaucoma (also closed-angle glaucoma): sudden and sharp increase in intraocular pressure caused by an obstruction of aqueous outflow (most commonly as a result of an occlusion of the iridocorneal angle ) and associated with optic neuropathy and visual field defects

sudden obstruction of the iridocorneal angle causing a rapid, acutely symptomatic, and vision-threatening elevation of IOP, often > 30 mm Hg

chronic obstruction of the iridocorneal angle with peripheral anterior synechiae resulting in an insidious and progressive rise in IOP that typically remains asymptomatic until glaucomatous optic neuropathy and irreversible visual field defects have developed

• Anatomic features predisposing to angle closure: shallow anterior chamber (e.g., hyperopia, short eye)

• Advanced age

• Female sex

• Asian or Inuit ethnicity [6][16]

• Eye injury with scarring and adhesions

• Rubeosis iridis

• Mydriasis

  • Drug-induced: anticholinergics (e.g., atropine) , sympathomimetics, decongestants

  • Darkness

  • Stress/fear response

• Common pathophysiology of angle-closure glaucoma: blockage of the trabecular meshwork → ↓ drainage of aqueous humor from the eye → ↑ IOP

• Primary angle-closure glaucoma: glaucoma due to an anatomical variant of ocular structure(s) that narrows the iridocorneal angle and increases the likelihood of trabecular meshwork obstruction

  • Shallow chamber depth (enhanced by mydriasis)

  • Small anterior segment of the eye

  • Plateau iris configuration

    • Most common cause of angle-closure glaucoma in individuals < 50 years of age [19]

    • An anatomical variant in which the iris is abnormally inserted in a more anterior position onto the ciliary body and lies on a horizontal plane (compared to its normal slightly convex plane), thus crowding the trabecular meshwork.

    • The anterior chamber depth remains normal.

• Secondary angle-closure glaucoma: glaucoma due to acquired conditions that occlude the iridocorneal angle with/without a pupillary block

  • Pupillary block → ↑ pressures in the posterior chamber of the eye → iris bulging forward → peripheral iris pressing against the cornea → narrowing of iridocorneal angle (anterior chamber angle) → blockage of the trabecular meshwork

    • Examples of conditions causing pupillary block

      • Inflammatory conditions (e.g., uveitis) causing posterior synechiae between the iris and lens

      • Anterior dislocation of the lens (ectopia lentis)

      • Enlargement of the lens (e.g., mature cataract)

  • Direct blockage of the trabecular meshwork (i.e., without a pupillary block). Examples include:

    • Inflammatory conditions causing peripheral anterior synechiae between the iris and cornea

    • Rubeosis iridis (neovascular glaucoma): hypoxia and the release of vasoproliferative substances (common in retinal ischemia due to central retinal vein occlusion or in diabetes mellitus) → angiogenesis of the iris and the ciliary body → narrowing of the anterior chamber angle