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L. M. Sakata, R. Lavanya, H. T. Aung, D. S. Friedman, P. J. Foster, T. Aung; Comparing Angle Closure Detected by Gonioscopy and Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1975.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the performance of anterior segment optical coherence tomography (AS-OCT) in detecting angle closure compared to gonioscopy.
This observational cross-sectional study evaluated 502 subjects with no previous ophthalmic problems recruited from a community clinic in Singapore. AS-OCT images of the four quadrants of the eye were obtained in dark conditions. Gonioscopy was performed in dim lighting condition by a masked examiner using the Shaffer grading system. An angle quadrant was classified as closed on gonioscopy if the posterior trabecular meshwork could not be seen (Shaffer grade 0 or 1). AS-OCT images were evaluated by a second examiner masked to other results. A closed angle quadrant on AS-OCT was defined by the presence of any contact anterior to the scleral spur between the iris and angle wall. Only right eyes were used in the analysis.
A closed angle in at least one quadrant was observed in 298/502 (59%) eyes by AS-OCT, and in 161/502 (32%) eyes by gonioscopy (p<0.001). The frequency of closed angles detected by AS-OCT and gonioscopy in the superior/inferior/nasal/temporal quadrants were: 246 (49%) vs 143 (28%); 199 (40%) vs 104 (21%); 89 (18%) vs 67 (13%); and 60 (12%) vs 89 (18%) respectively. The overall agreement between AS-OCT and gonioscopy in detecting angle closure was fair (kappa=0.37). Among 129/2008 quadrants that were closed on gonioscopy but open on AS-OCT, an "over the hill" iris configuration (left image) was present in 115 (89%) quadrants, and of the 335/2008 quadrants that were open on gonioscopy but closed on AS-OCT, 250 (75%) quadrants showed low irido-angle contact on AS-OCT (right image).
AS-OCT identified more eyes as having angle closure than gonioscopy, particularly in the superior /inferior quadrants. Agreement between the two methods was fair. Variations in iris profile and level of irido-corneal contact may account for some of these differences.
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