Purchase this article with an account.
Jiawei Zhou, Benjamin Thompson, Robert Hess; Patching therapy for amblyopia, are we patching the wrong eye?. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4980.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Patching therapy has been commonly used clinically to improve visual functions in the amblyopic eye by occluding the fellow eye under the assumption that amblyopia is a purely monocular deficit. However, there is emerging evidence that amblyopia is the result of binocular sensory imbalance resulting in suppression. Here we show that the binocular imbalance that characterizes amblyopia can be reduced by occluding the amblyopic eye, the opposite to what has been done for the last 200 years.
The experiment consists of three consecutive stages: a pre-patching measurement of binocular balance, a patching stage (2.5 hours) and a post-patching measurement of binocular balance. The effect of transparent patching (transmitting light but not pattern) on binocular sensory balance was quantified using a binocular phase combination paradigm. In this measure, two monocular sine-wave gratings with phase-shifts in opposite directions by same magnitude were dichoptically presented to the two eyes. The perceived phase of the grating after binocular combination is depended by the internal representations of the two inputs. Therefore, any variations of the binocular sensory balance could be quantified by the changes of the perceived phase.
While the magnitude of the patching effect varied across amblyopic participants, similar time courses were apparent. Immediately after the patch was removed, the amblyopic eye became significantly stronger in its contribution to the binocular percept. This effect weakened a little in the first 6 minutes after the patch was removed but increased much more and lasted for a long time thereafter. The greatest change in binocular balance occurred at about 30-50 minutes after the patch was removed. For our patients, the beneficial effects of patching lasted as long as 50 minutes. In normal controls, a similar patching effect occurred but had quite a different time course. The greatest effect occurred immediately after the patch was removed. This effect decreased thereafter and was at baseline at around 30 minutes after the removal of the patch.
Our study provides novel data for occluding the amblyopic eye. Our data suggest that short duration of transparent patching could significantly strengthen the amblyopic eye’s contribution to binocular combination.
This PDF is available to Subscribers Only