It was argued that using the eye patch for long hours was excessive. But now, studies have shown that occlusion therapy (patching) can improve vision with its use for 6 hours day for 12 weeks and 12 hours a day.
Despite this, many doctors still suggest large doses of patching, so, researchers at City University in London and McGill University in Montreal funded by Fight for Sight, London, decided to determine the amount of patching required in children with amblyopia to achieve the best outcome.
Researchers conducted a study that involved 97 children aged 3-8 years with a confirmed diagnosis of amblyopia. All these children had a full ophthalmic assessment and were instructed to wear glasses all the time for 18 weeks.
When the phase was completed, 80 children who still met the study's definition of amblyopia were instructed to wear a patch for either six or 12 hours a day.
To monitor the amount of occlusion each child actually received, two electrodes were attached to the under surface of each patch and visual function was recorded every two weeks.
The outcome was that no major difference was found in visual acuity between the two groups. However, the mean dose rates (hours a day with a patch) actually achieved were also not significantly different (4.2 in the six hour group and 6.2 in the 12 hour group).
Both groups who received patching for 3-6 hours a day and 6-12 hours a day showed similar improvement, but significantly worse for children who received less than three hours a day.
This suggested that children under 4 years of age required significantly less occlusion which means less than 3 hours to correct their vision.
This analysis concluded that dose should be taken for three to four hours a day for the best outcome and doctors too should prescribe the same.
And also said that dose should be given according to age such as dose in children of 4 years carrying amblyopia could be reduced.
Therefore, eye patching can cause considerable distress for both the child and family and doctors should try to minimise the amounts necessary for the best expected outcome.