Through an eyeglass oddly.

Through an eyeglass oddly

Vision researchers working with bespectacled chickens find the birds' eyeballs can shrink or grow as needed to compensate for eyeglass-induced near- or far-sightedness. The research suggests eyeglasses can cause, as well as correct, changes in ocular acuity. Indeed, the researchers say, doctors someday may correct some visual problems with drugs rather than corrective contact lenses or glasses.

"These experiments are the first direct demonstration of a feedback loop controlling growth of the eye," says one of the researchers, Howard C. Howland, at Cornell University in Ithaca, N.Y. "If the same feedback loops operate in humans, it would mean that placement of lenses on the eyes of young children could conveivably affect the growth of the eyes."

Howland and his colleagues report in the May VISION RESEARCH that chickens fitted with prescription glasses experimence permanent changes in eyeball size and concomitant changes in image focusing. The scientists used a technique called infrared photoretinoscopy to detect where in the chickens' eyes images were focused. They say insight into bioregulation of eye size may lead to the use of growth inhibitors or enhancers to resolve certain vision defectss.