Hyperacuity test to evaluate vision through dense cataracts: research preliminary to a clinical study in India

摘要: Using high luminance point-of-light stimuli, Vernier judgments can be made in the presence of markedly degraded retinal imagery. Without coaching, observers perform center-of-gravity assessments relative locations point images. We seek to define, presurgery, individuals who will derive most benefit from advanced cataract removal (a form triage), and determine which two cataractous eyes has better postsurgical visual prognosis. There are incredible growing backlogs patients with severe cataracts (and other dense media opacities) developing world, generally, limited resources available for provision health care. Postcataract surgical failure rates good function often high, only one eye is operated on over 95% indigent treated. Prior initiating studies at Berkeley we conducted preliminary research acuity test techniques normal adult subjects. sought number repeat trials necessary; compare a two-point three-point display; shape measured response large gap separations between points (required when testing patients); assess effect(s) broad range uncorrected refractive errors outcomes; consider means minimize refraction-based errors. From these prior data analyses, defined protocol use world. newly designed rugged precision instrument, tests were repeated an population Aravind Eye Hospital Madurai, India. Although had much experience India, initial required major revision site. Necessary changes methods analytical approaches made, next stages this program planned. And new simple «visual acuity» (gap «VA») was added protocol, greatly facilitated outcome. The presented material interest several reasons: care problems addressed considerable social economic importance; it valuable instrument resultant designs that finally evolved India; difficulties encountered seeking adapt what thought patient populations technical personnel «small town setting» (ca. 1 million inhabitants Madurai alone) rural south worthy note. out ophthalmological exemplar world