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T. Aung, R. Lavanya, L. M. Sakata, H. T. Aung, H. Gao, T. Alfred, S. K. Seah, K. Kashiwagi, D. S. Friedman, P. J. Foster; Screening for Angle Closure in the Singapore Population: Evaluation of 3 New Non-Contact Devices. Invest. Ophthalmol. Vis. Sci. 2007;48(13):866.
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To assess the screening effectiveness of three new non-contact devices, the scanning peripheral anterior chamber depth analyzer (SPAC), which measures central and limbal anterior chamber depth (ACD); the IOL Master, which measures central ACD and the Visante anterior segment OCT (AS-OCT), which images the angles directly, and to compare these instruments with gonioscopy in identifying people with angle-closure.
Subjects aged 50 years and older without ophthalmic complaints were recruited from a health clinic in Singapore. All subjects underwent examination with SPAC, IOL-Master and AS-OCT in the dark by a single operator. Gonioscopy was performed by a masked ophthalmologist. Eyes were classified as having angle closure if the posterior pigmented trabecular meshwork could be seen for less than two quadrants of the angle circumference. The area under the receiver operating characteristic curve (AUC) was generated to assess the performance of these tests in detecting persons with angle closure in either eye.
2076 subjects were examined and underwent all 3 tests. The prevalence of angle closure in at least one eye diagnosed by gonioscopy was 20.4% (423 subjects). The AUC for SPAC using the numerical grade ≤ 5 as a cutoff was 0.84 (95%CI: 0.82-0.85), with a sensitivity of 90.1% (95%CI: 86.8-92.7) and a specificity of 76.8% (95%CI: 74.7-78.8). The AUC using the IOL-Master at a cut-off ACD of 2.87 mm was 0.83 (95%CI: 0.81-0.85), with a sensitivity of87.5% (95%CI: 83.9-90.5), and a specificity of 77.7% (95%CI: 75.7-79.7). The AUC using the AS-OCT (only nasal and temporal angles graded) was 0.70 (95% CI: 0.68 -0.73), with a sensitivity of 58.4 (95% CI: 53.5 -63.1) and specificity of 82.2% (95% CI: 80.2 -84.0).
New non-contact devices that rely on ACD measurement such as SPAC and IOL-Master have the potential to be used in screening for angle closure.
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