Boston, MAScientists at Schepens Eye Research Institute, an affiliate of Harvard Medical School, have discovered a simple and inexpensive way for patients with retinal and other eye disease to keep track of changes in their vision loss. In a study published in this weeks PLoS ONE (October 24, 2007) they demonstrate that a compelling visual illusion known as the induced twinkle after-effect (TAE) can accurately identify the location and breadth of actual blind spots in people with retinal disease. The twinkle after-effect is a twinkling that people can see in a blind spot when they stare at a blank screen after staring at a noisy visual target such as a detuned television screen.
Our hope is that we can make this simple technique available online or on a DVD, says Dr. Peter Bex, associate scientist at Schepens Eye Research Institute and the principal investigator of the study. This will be particularly helpful with patients who have glaucoma, diabetic retinopathy or macular degeneration where early detection of changes in vision can impact the effectiveness of treatments.
According to Bex, many people fail to seek help when they develop blind spots in their vision, because their brains automatically compensate or fill in the missing information in their visual field. Since everyone has a blind spot where the optic nerve meets the retina, this perceptual fill in process is useful for normally sighted people, allowing them a complete visual image. But this innate process can mask the effects of serious disorders such as diabetic retinopathy and glaucoma and keep sufferers from seeking help until the vision loss is very serious or they bump into objects they can no longer see.
The traditional gold standard method for detecting blind spots (scotomas) is very expensive and time consuming and must be done in an ophthalmologists office. The technique known as retinal specific microperimetry is a diagnostic tool that costs nearly 50 thousand
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