'Twinkle after-effect' can help retinal patients detect vision loss quickly a...(dollars and requires specialized trainin...)

In 1992 scientists became aware of what they eventually named the twinkle after effect. They discovered that when someone looks at a television screen filled with static noise while covering part of their visual field with a small patch, the formerly patched area is left with a twinkling sensation after the noise is turned off and the person looks at a blank screen. The rest of the visual field does not experience the twinkling effect, which was described by one patient as resembling a moving cumulous cloud. While this discovery was intriguing, it wasnt clear how it could be used for patients, says Bex.

In the past several years, Bex and his team began to understand its potential. We theorized that if people with blind spots stared at a noisy screen, the blind areas would twinkle when the screen was turned off and their eyes focused on a blank screen. These twinkling blind spot areas could then easily be mapped, he says.

To test their theory, Bex and his team asked eight patients with macular degeneration to undergo the retinal specific microperimetry test and his twinkling after-effect test. The team provided a blank touch screen--after the noisy screen--so patients could outline the twinkling areas with their finger.

The team found that the results of the two tests matched in 75 percent of cases, and visual defects could be detected in areas that are not accessible to conventional microperimetry, confirming his belief that TAE could be used diagnostically. This tool cannot replace the more sophisticated technique but we believe it is a powerful, simple tool that patients can use daily in the privacy of their home to detect any changes in their vision, he says. If a patient detects a change, his or her physician can then study it more closely and offer therapy.

While the results of this small study are very encouraging, Bex says the next step is to do a larger clinical
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