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Reverse Amblyopia by L. E. Leguire Ph.D., MBA
Reverse amblyopia refers to amblyopia that develops in the good or sound eye usually as a result of traditional amblyopia treatment, either patching (occlusion) or penalization (e.g., atropine). For example, a child may have newly diagnosed amblyopia of the left eye (visual acuity 20/80) and a normal right eye (20/20). The child with the amblyopic left eye may be prescribed patching therapy for, say, 3 hours per day of the sound, right eye (visual acuity 20/20). When the patient returns to the eye doctor, visual acuity could have gotten worse in the right eye (decline to 20/40) and may have improved in the left, amblyopic eye to 20/20. The visual acuity in the right eye, which decreased from 20/20 to 20/40, was the result of patching the right eye in hopes of improving vision in the left, originally amblyopic, eye. In a sense, the amblyopia revered eyes; thus "reverse amblyopia." When reverse amblyopia occurs, your eye doctor will determine the most appropriate treatment course. Depending on the circumstances, the eye doctor may stop patching for a period of time and retest the patient at a later date to see if the reverse amblyopia has resolved on its own. In other cases, your eye doctor might patch the original amblyopic left eye if vision is better in that eye. In the NEI-NIH funded Amblyopia Treatment Studies (ATS), which include nationwide multicenter clinical trials for amblyopia, the following is recommended: " [Amblyopia] treatments potentially could decrease the visual acuity in the sound eye, although this is almost always reversible. The diagnosis and management of reverse amblyopia is left to the investigator’s [eye doctor's] judgment. If reverse amblyopia is suspected, a suggested routine for evaluation is described in the ATS protocol: 1. If not already done, recheck acuity using full hyperopic correction from most recent cycloplegic refraction. 2. If acuity is still decreased, perform refraction and recheck acuity if testing was not done with full hyperopic correction. 3. If acuity is still worse, stop therapy and repeat visual acuity testing in one week. 4. If the visual acuity has returned to enrollment level [i.e., normal], resume treatment as per protocol. 5. If still reduced after one week…the patient is considered a treatment failure [for the purposes of the study]." The above quote from the ATS studies manual suggests that the first approach to reverse amblyopia is to make sure that it exists by double checking the patient's refractive error and by double checking the patient's visual acuity. If after this double checking the patient still has reduced vision in the (previously) good eye than therapy can be stopped and visual acuity rechecked in one week. If, after one week, visual acuity in the previously good eye is still decreased than the patient is dropped from the particular ATS study and the eye doctor can then pursue the treatment deemed most appropriate for the particular situation. Most of the time, however, reverse amblyopia will resolve or get better once the patient is provided his or her best glasses and given a period of binocular vision. Numerous references have stated that reverse amblyopia is "rare" (North and Kelly, 1991; Simon et al, 1987). But how rare is reverse amblyopia? Possibly more common than originally believed: when reverse amblyopia was defined as a loss of 2 or more lines on the visual acuity chart, the estimates of reverse amblyopia after 4 months of treatment ranged from 4% to 10% and depended on the amount of patching time (The Pediatric Eye Disease Investigator Group, Ophthalmology, 2003). If the patients were patched for 6 hours per day there was a 4% chance (1 in 25) of reverse amblyopia and if the patients were patched all day or all day except for one hour they had a 10% chance (1 in 10) of reverse amblyopia. Reverse amblyopia is one more reason why it is important to maintain your child's eye doctor appointments. Your eye doctor will closely follow your child's visual performance in both eyes and check to make sure that vision remains normal in the good or sound eye. If detected early, reverse amblyopia is seldom permanent and may resolve spontaneously by temporarily halting patching therapy and providing best optical correction.
This web site is funded by The Ohio Department of Health, Bureau of Child and Family Health Services, Save Our Sight Program.
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