The Significance of Preattentive Visual Search (PAVS) in Glaucoma

The Significance of Preattentive Visual Search (PAVS) in Glaucoma Methods: A novel test of PAVS, incorporating tests for flicker, motion displacement and orientation, presented on a computer monitor was developed for the detection and monitoring of glaucoma. Patients were required to detect a unique target from a background of 119 distractors. Normality was determined on the basis of patient response times measured using a two-alternative forced choice paradigm. Data were collected on 123 subjects, 41 with existing glaucoma, 41 glaucoma suspects, and 41 age-matched normals. Results: Paired samples t test indicated a statistically significant difference in PAVS response times between subjects with diagnosed glaucoma, and both glaucoma suspects and normal controls (p \u3c 0.001 for both). More interestingly however, the test also discriminated between suspects and normals (p \u3c 0.01). Test sensitivity and specificity was greater than 90% for all test paradigms. Additional experimental analyses have further demonstrated that the test remains resistant to the potential confounding effects of optical blur, age and target eccentricity. Discussion: The data support the concept that glaucoma adversely affects preattentive visual search mechanisms (which allow simultaneous analysis of the entire retinal image and therefore presumably requires normal retinal and cortical function). Conclusion: The battery of tests used allows targeting of both the parvocellular and magnocellular pathways, and thereby may facilitate early detection of glaucoma. The tests are fast, patient friendly, and require only a PC and appropriate software