Purpose: To assess the screening effectiveness of 3 new noncontact devices, the scanning peripheral anterior chamber depth analyzer (SPAC) (Takagi, Nagano, Japan), which measures peripheral anterior chamber depth (ACD); IOLMaster (Carl Zeiss Meditec, Jena, Germany), which measures central ACD; and Visante anterior segment optical coherence tomography (AS-OCT) (Visante, Carl Zeiss Meditec, Dublin, CA), which images the angles, and to compare these instruments with gonioscopy in identifying people with narrow angles (NAs).
Design: Cross-sectional, observational, community-based study.
Participants: Phakic subjects aged >or=50 years without ophthalmic symptoms who were recruited from a community polyclinic in Singapore.
Methods: All subjects underwent examination with SPAC, IOLMaster, and AS-OCT in the dark by a single operator. Gonioscopy was performed by an ophthalmologist masked to the instruments' findings. The area under the curve (AUC) receiver operating characteristic (ROC) was generated to assess the performance of these tests in detecting people with a NA in either eye.
Main outcome measures: Eyes were classified as having NAs by gonioscopy if the posterior pigmented trabecular meshwork could be seen for <or=2 quadrants of the angle circumference with or without peripheral anterior synechiae.
Results: A total of 2052 subjects were examined and underwent all 3 tests. The prevalence of a NA in at least 1 eye diagnosed by gonioscopy was 20.4% (422 subjects). The AUC for the SPAC using a numeric grade <5 as a cutoff was 0.83 (95% confidence interval [CI], 0.82-0.85), with a sensitivity of 90.0% (95% CI, 86.8-92.7) and a specificity of 76.6% (95% CI, 74.4-78.6). The AUC for the IOLMaster at an ACD cutoff of <2.87 mm was 0.83 (95% CI, 0.81-0.85), with a sensitivity of 87.7% (95% CI, 84.2-90.7) and a specificity of 77.7% (95% CI, 75.6-79.7). The AUC for the AS-OCT was 0.76 (95% CI, 0.74-0.78), with a sensitivity of 88.4% (95% CI, 84.9-91.3) and a specificity of 62.9% (95% CI, 60.5-65.2).
Conclusions: The low specificity found with the SPAC, IOLMaster, and AS-OCT may limit the usefulness of these devices in screening for NAs.