Page 88 - NAME OF CONDITION: REFRACTIVE ERRORS

NAME OF CONDITION: ANGLE CLOSURE DISEASE

I. WHEN TO SUSPECT/ RECOGNIZE?

a) Introduction:

‘Angle closure’ implies either appositional or synechial closure of the anterior
chamber angle. This iridotrabecular contact (ITC) may or may not be associated with
raised intraocular pressure (IOP) or glaucomatous optic neuropathy. Various
mechanisms are postulated in pathogenesis of primary angle closure (PAC), of which
pupillary block constitutes a key element. This results in obstruction of aqueous flow
from posterior chamber of eye to the anterior chamber, resulting in anterior bowing
of iris and consequent crowding of the chamber angle. Prolonged apposition may
lead to mechanical or functional obstruction to trabecular meshwork outflow and
may result in formation of peripheral anterior synechiae (PAS), causing raised

intraocular pressure and glaucomatous optic neuropathy. There are various other
causes of ITC including position and thickness of ciliary body, iris thickness, lens
position and thickness. Secondary angle closure can also occur in neovascularization,
inflammation and gas or oil tamponade of posterior chamber besides other causes.

b) Case definitions:

Angle closure disease had been classified earlier on the basis of presence or absence
of symptoms into three subtypes as acute, intermittent and chronic angle closure
.Intermittent and chronic angle closure have since then been reclassified into PAC
and PACG as described above.

In recent years, there has been an effort to standardize diagnostic definitions of
angle closure glaucomas based on suggestions by International Society of
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Geographical and Epidemiological Ophthalmology (ISGEO). More emphasis is placed
on structural (optic nerve head) and functional (visual field) changes to diagnose
glaucoma. The amount of ITC (apposition between iris and posterior trabecular
meshwork) required to define primary angle closure has been debated. By
consensus, an eye with 180 degrees or more of ITC in dim illumination and non
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compressive gonioscopy is classified as one having primary angle closure disease.
Based on associated findings this is further subclassified as:

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