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Study links iris thickness to angle-closure and primary angle-closure glaucoma
Br J Ophthalmol. 2011:95:46-50.
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Increased iris thickness was associated with angle-closure and progression to glaucoma, according to a large study in Singapore.
"The results suggest that an increased iris thickness may play a role in angle closure pathogenesis," the study authors said.
They set out to gauge the relationship between quantitative iris parameters such as iris curvature, cross-sectional area and thickness, and primary open angle glaucoma.
The prospective study included 167 patients with angle closure and a control group of 1,153 normal participants. The group of 167 angle closure patients comprised 50 patients with primary acute glaucoma, 73 patients with primary angle closure glaucoma and 44 fellow eyes of acute primary angle closure.
About 90% of patients were of Chinese descent.
All patients underwent anterior segment optical coherence tomography imaging. Investigators used customized software to measure iris thickness at 750 µm and 2,000 µm from the scleral spur, maximum iris thickness and cross-sectional area of the iris.
Study results showed that mean iris thickness 750 µm from the scleral spur was 0.499 mm in angle-closure eyes and 0.451 mm in normal eyes. Mean iris thickness 2,000 µm from the spur was 0.543 mm in angle-closure eyes and 0.479 mm in normal eyes. The between-group differences were statistically significant (P < .001).
Maximum iris thickness was 0.660 mm in the angle-closure group and 0.602 mm in the control group. The statistical variance was significant (P < .001).
Angle closure also correlated with age, shallow anterior chamber depth, narrower angles, smaller pupil size and female gender, the authors said.