Comparison of Gonioscopy and Anterior Segment Ocular Coherence Tomography in Detecting Angle Closure in Different Quadrants of the Anterior Chamber Angle
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Abstract
To compare the performance of gonioscopy and anterior segment (AS) optical coherence
tomography (OCT) in detecting angle closure in the different quadrants of the anterior
chamber angle (ACA).
Cross-sectional observational study.
Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic
problems recruited from a community clinic in Singapore.
All subjects underwent gonioscopy and AS OCT imaging in the dark. Using gonioscopy,
the ACA was graded using the Scheie system by a single examiner masked to AS OCT findings.
The ACA in a particular quadrant was classified as closed if the posterior trabecular
meshwork could not be seen on gonioscopy. A closed ACA on AS OCT imaging was defined
by the presence of any contact between the iris and angle wall anterior to the scleral
spur.
After excluding eyes with poor image quality, a total of 423 right eyes were included
in the analysis. A closed angle in at least 1 quadrant was observed in 59% of the
eyes by AS OCT and in 33% of the eyes by gonioscopy (P<0.001), with fair agreement
between the two methods (kappa = 0.40). The frequency of closed angles by AS OCT and
gonioscopy were 48% versus 29% superiorly, 43% versus 22% inferiorly, 18% versus 14%
nasally, and 12% versus 20% temporally, respectively. Of the 119 of 1692 quadrants
that were closed on gonioscopy but open on AS OCT, a steep iris profile was present
in 61 (51%) of 119 quadrants on AS OCT, and of the 276 of 1692 quadrants that were
open on gonioscopy but closed on AS OCT, 196 (71%) of 276 quadrants showed short iridoangle
contact on AS OCT.
The highest rates of closed angles on gonioscopy and AS OCT images were observed in
the superior quadrant. Anterior segment OCT tended to detect more closed ACAs than
gonioscopy, particularly in the superior and inferior quadrants. Variations in the
iris profile and level of iridoangle contact also may explain some of the differences
seen between gonioscopy and AS OCT.