Peristat: a computer-based perimetry self-test for cost-effective population screening of glaucoma

Peristat is a virtual perimetry system that allows self-testing on any standard computer monitor via Internet connection. The sensitivity and specificity of Peristat to detect visual-field defects were compared to standard Humphrey Visual Field Analyzer data.

In this prospective, comparative observational case series, 58 eyes of 33 patients were examined. Semiquantitative analyses compared Peristat and Humphrey Visual-Field scores. The study evaluated patients with an established glaucoma diagnosis, as well as glaucoma suspects who had undergone comprehensive ophthalmologic examinations including prior office perimetry evaluation (Humphrey Field Analyzer). Inclusion criteria were (1) diagnosis or suspicion of glaucoma, (2) BCVA better than 20/200, (3) reliable performance on prior standardized office perimetry, and (4) CDR greater than 0.5. Computer literacy was not required, and more than 40% of the patients tested were computer illiterate, with no previous computer or Internet experience. A total of 58 eyes of 33 patients were tested with the Humphrey and the Peristat systems: 10 eyes of 5 patients without documented glaucomatous field loss and 48 eyes of 23 patients with mild-to-severe scotomas by standard 24-2 office perimetry. A standard computer setup was used with a 17" monitor, and the Peristat system was enabled through a remote connection with a server.

All patients completed the Peristat test without difficulty. Testing time varied between 2 and 5 min, tending to be longer with more severe visual-field defects. Test results were reviewed, in a masked fashion, by two glaucoma specialists and one general ophthalmologist. The Peristat demonstrated a high degree of correlation with the Humphrey system. Among the three reviewers, sensitivity ranged from 80% to 83%. In a second subanalysis in which cases with mild defects were excluded, the Peristat's sensitivity increased to 84%-86% while specificity remained between 94% and 97% for all three reviewers. Patients performed the Peristat test with similar facility to their Humphrey test. Fixation losses and test reliability were comparable for both tests.

Peristat is a reliable self-test perimetry system that demonstrates high clinical utility for the detection of visual-field defects from glaucoma. Peristat could be a valuable public health tool for cost-effective screening of glaucoma.