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MANAGING OPEN ANGLE GLAUCOMA

• Ciliary body:
• After the iris, the most posterior structure seen during gonioscopic assessment of a wide-open angle is
the ciliary body (CB).
• The CB appears as a brownish-grey band at the root of the normally less-pigmented iris.

• It is more obvious in deeper angles.

• An extremely wide CB band or intra- or inter-ocular asymmetries in CB visibility, particularly following
blunt trauma, may indicate angle recession, or irido- or cyclodialysis. Blunt trauma may also result
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in ‘balls’ of angle pigmentation (breakdown products of red blood cells following hyphema) and increased
intraocular pressure representing ghost cell glaucoma. 388

• Scleral spur:
• The scleral spur (SS) is the insertion site of the ciliary muscle, and is visualized as a white line lying
between the CB and the posterior (pigmented) trabecular meshwork (TM).

• It is an important and often quite conspicuous landmark, identifying everything anterior to the SS as TM.

• Benign iris processes (fine pigmented strands running from the iris root to posterior TM) or pathologic
peripheral anterior synechiae (PAS, broad-based adhesions between the iris and TM resulting from
chronic appositional closure (most often seen superiorly) or inflammation (most often seen inferiorly))
may obscure the SS.
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• As previously noted, indentation gonioscopy can help differentiate appositional from synechial angle
closure:
• in the former, pressure on a small diameter goniolens will force the lens-iris diaphragm
posteriorly and open the angle, while the angle will remain closed in areas of PAS.
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• patients with appositional closure usually benefit from laser peripheral iridotomy (LPI), while
those with synechial closure may require incisional surgery.391

• Trabecular meshwork (TM):
• Anterior to the SS is found the trabecular meshwork, which is divided into the posterior (functional) TM
and the anterior (non-functional) TM.
• The pigmented functional uveal TM, the posterior two-thirds of the TM, overlies canal of Schlemm and
as the descriptor “functional” suggests, is the portion of the TM that filters aqueous.

• Anterior to that lies the less-pigmented non-functional corneoscleral TM: its light and even bluish-
grey pigmentation of youth normally increases with age.
• TM pigment can pathologically increase due to trauma, inflammation, pigment dispersion,
and exfoliation.
• In some lightly pigmented eyes, canal of Schlemm may be visible as a slightly darker or red line
(the latter in the presence of increased episcleral venous pressure forcing blood into the canal) deeper
to the posterior TM.
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• Pharmacologic pupil dilation is typically safe if the posterior pigmented TM is visible in at least two full
quadrants (180 ) of the angle.
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CANADIAN JOURNAL of OPTOMETRY | REVUE CANADIENNE D’OPTOMÉTRIE VOL. 79 SUPPLEMENT 1, 2017 59