Bangalore: Eye doctors have traditionally believed that loss of eyesight in adults on account of the so-called “lazy-eye” condition is irreversible. Now, new research shows that “lazy eye”, or amblyopia, which is one of the most common causes of blindness and often considered irreversible, if detected after the age of eight, can now be corrected in adults by a simple treatment.
Between 30 million and 40 million people in India suffer from the condition.
Researchers from the University of Science and Technology of China in Anhui and University of Southern California in Los Angeles reported in Monday’s issue of the Proceedings of the National Academy of Sciences, US, that new evidence from laboratory studies and a pilot clinical trial suggests that a simple computer training exercise can be an effective therapy for amblyopia.
The treatment has proved effective on 20-year-old subjects, when amblyopia has been considered mostly irreversible, if not corrected by eight years of age. “In a pilot clinical trial at a Beijing hospital, 28 out of 30 patients showed dramatic gains after a 10-day course of treatment,” said Zhong-Lin Lu, the neuroscientist from the University of Southern California, who led the research group.
Anecdotal evidence of the “lazy eye” being corrected in adults, through different interventions, has always been around but this is the first systematic study on the “generalizability of training on adult ambyopes”. “This is a brilliant report and provides hopes for millions of patients as they’ve been deprived for far too long,” said Mahipal S. Sachdev, director of Centre for Sight in New Delhi.
“Lazy eye” occurs when the vision in one eye does not develop properly during childhood. If not treated on time, it can lead to a permanent problem, ranging from poor vision in one eye, poor depth perception, difficulty seeing three-dimensional objects and poor motion sensitivity.
Researchers say the condition, especially in developing countries, is often diagnosed too late for conventional treatment with an eye patch— an opaque patch is worn over the stronger eye for a few hours every day.
“It affects anywhere between 30 million to 40 million people in India,” said Dr Sachdev, who has noticed sporadic cases of improvement in adults after laser surgery and thinks Lu’s study of giving visual stimuli is noteworthy.
The research revisits the neurological basis of the disorder. “For amblyopes, the neural wiring is messed up. Any improvement you can give to the system may have much larger impacts on the system than for normals,” said Lu. His findings challenge the assumption that the visual system loses plasticity and ability to change after a certain age.
Researchers found that most of the patients regained vision after an hour-long training exercise on computer screens for nine days. However, Jyoti Matalia, paediatric ophthalmologist at Narayana Nethralaya in Bangalore, said the study involved very few patients and the researchers studied “only contrast-sensitivity functions which though may indicate increased plasticity, but cannot be entirely extrapolated to visual function”.
Lu said they were working towards making the procedure more “efficient” and more “effective”. “We are also trying to adapt the training programmes in the lab to home computer setups,”he added.
That may be a positive step, but experts believe multi-centric, bigger studies are needed before this finding can be used. “A larger number of patients need to be studied to confirm the results of the research,” said Dr Matalia.