Anterior Segment OCT for Detection of Narrow Angles

Purpose

To assess the diagnostic accuracy of anterior segment OCT (AS-OCT) screening for detecting gonioscopically narrow angles.

Design

Population-based cross-sectional study.

Participants

A stratified random sample of individuals aged ≥ 60 years, selected from a door-to-door census performed in low-lying Nepal.

Testing

Participants underwent AS-OCT, posterior segment OCT, and intraocular pressure (IOP) testing in the community. Those meeting referral criteria in either eye were invited to have a comprehensive eye examination including gonioscopy. Referral criteria included (i) the lowest 2.5% of AS-OCT measurements, (ii) retinal OCT results suggestive of glaucomatous optic neuropathy, diabetic retinopathy, or age-related macular degeneration, and (iii) elevated IOP.

Main Outcome Measures

Sensitivity and specificity of 5 semiautomated AS-OCT parameters relative to gonioscopically narrow angles, defined as the absence of visible trabecular meshwork for ≥ 180° on nonindentation gonioscopy.

Results

Of 17 656 people aged ≥ 60 years enumerated from 102 communities, 12 633 (71.6%) presented for AS-OCT testing. Referral was recommended for 697 participants based on AS-OCT criteria and 2419 participants based on other criteria, of which 858 had gonioscopy performed by a glaucoma specialist. Each of the 5 AS-OCT parameters offered good diagnostic information for predicting eyes with gonioscopically narrow angles, with areas under the receiver operating characteristic curve ranging from 0.85 to 0.89. The angle opening distance at 750 μm from the scleral spur (AOD750) provided the most diagnostic information, providing an optimal sensitivity of 87% (95% confidence interval [CI], 75%–96%) and specificity of 77% (71%–83%) at a cutpoint of 367 μm, and a sensitivity of 65% (95% CI, 54%–74%) when specificity was constrained to 90% (cutpoint, 283 μm).

Conclusions

On AS-OCT, the AOD750 parameter detected approximately two-thirds of cases of gonioscopically narrow angles when test specificity was set to 90%. Although such a sensitivity may not be sufficient when screening solely for narrow angles, AS-OCT requires little additional effort if posterior segment OCT is already being performed and thus could provide incremental benefit when performing OCT-based screening.

Financial Disclosure(s)

The authors have no proprietary or commercial interest in any materials discussed in this article.