A child with amblyopia (lazy eye) does not have to wear a patch all day; three to four hours daily for a total of twelve weeks is all that is usually needed to improve vision, according to an article published in the British Medical Journal (BMJ). The writers say that wearing a patch all day long for several years is too much.
Amblyopia happens when the vision pathways between the eye and the brain are disturbed. The patient commonly experiences blurred vision and/or has strabismus (crossed eyes).
Previous studies have demonstrated that wearing a patch (occlusion therapy) can help improve vision. Results have shown that making the child wear the patch all day (maximal doses) offers the child no more improvement than six hours a day (substantial doses). Surprisingly, many doctors still make their patients wear the patch for too many unnecessary hours.
Scientists from City University, London, England, and McGill University, Montreal, Canada, decided to find out how much occlusion treatment a child with amblyopia needs to get the best results. The study was funded by Fight for Sight.
In this study, all the 97 children, aged 3-8 years had amblyopia. All of them underwent a full ophthalmic assessment and were told to wear glasses during their waking hours for a period of 18 weeks. At the end of this period the number of children who still had amblyopia went down to 80. These children were split into two groups; one group wore a patch for six hours a day while the other group did so for twelve hours a day – for a total of 12 weeks.
The patches had two electrodes fitted inside them to register the exact amount of occlusion time each child was receiving. The visual function of each participant was recorded every two weeks.
At the end of the period the researchers could not detect any difference in visual activity between the two groups. They also found that the real amount of time the children were receiving occlusion therapy was much lower than what had been prescribed. The 12 hour per day group’s average daily occlusion time was 6.2 hours, while the 6 hour per day group’s was 4.2 hours.
Children over 4 years of age who received less than three hours treatment per day had significantly worse outcomes than those who received from 3-6 hours per day. However, the children who received 3-6 hours per day treatment enjoyed virtually similar improvements as the children who had 6-12 hours per day.
It was also noticed that the younger the patient was the less total occlusion hours he/she required. In fact, the 4 year-olds required less than three hours per day.
The writers explain that it should be a clinical priority to start the initial real occlusion rate of 3-4 hours per day. As eye patching can be very upsetting for both the patient and his/her family, doctors should endeavor to keep the amount of time necessary for best outcomes down to a minimum.
Written by: Christian Nordqvist