Treatment Of The Amblyopes Beyond The Critical Period Of Visual Development By Interocular Shift Of Visual Attention

Amblyopia has been defined as a unilateral or bilateral decrease of visual acuity caused by deprivation of pattern vision or abnormal binocular interaction without apparent structural abnormality of the eyeball, where the best corrected visual acuity of one or both eyes remains weaker than the normal range of corresponding age.Amblyopes beyond the critical period of visual development is the most common cause of monocular impairment worldwide. Its prevalence is about3%in general population.Traditional amblyopia treatments aim primarily at children under12years of age. After this age the visual system is thought to have passed its susceptible period and have no plasticity, and the amblyopia is generally left untreated. Recently, more and more studies showed notable visual improvement of amblyopic eye in older patients. We aim to observe the effective to amblyopes beyond the critical period of visual development by the novel program-interocular shift of visual attention training under binocular condition.PURPOSE To compare the effective treatment from traditional occlussion and interocular shift of visual attention training under binocular condition to amblyopes beyond the critical period of visual development. METHODS A total of twenty-seven adults,ranging from13to34years of age (average of25.7years old),with anisometropic and or strabismic amblyopia were trained. The severity of pre-training acuity loss in the amblyopic eye varied within our sample from mild to severe. Amblyopic patients were recruited and randomly assigned into two groups(traditional occlusion or interocular shift of visual attention training). All of the participants in the trial underwent initial ocular examination that included assessment of the best-corrected spectacle visual acuity or through the surgery of strabismus before training.A copy of this novel program was given to the patients to let them have self-training at home.Best corrected visual acuity (BCVA), Titmus stereopsis and Yan’s random-dot stereopsis were assessed in each follow-up. RESULTS1. Results of the anisometropic amblyopes indicate improvement in all two groups in visual acuities of the amblyopic eye without a particular indication towards any treatment group. However, results for improved stereopsis were statistically significantly higher (p<0.05) in group that treating by our novel binocular therapy approach. These results demonstrated that there was statistical difference in these parameters between pre-training and post-training of Titmus stereotests and Yan’s random-dot stereogram.2. Results of the strabismic amblyopes indicate improvement in all two groups in visual acuities of the amblyopic eye without a particular indication towards any treatment group. However,results for improved stereopsis were statistically significantly higher (p<0.05) in group that treating by our novel binocular therapy approach.3. Interocular shift of visual attention training is much better to amblyopes in different type of amblyopia beyond the critical period of visual development, especially stereopsis.4. Results of the strabismic and anisometropic amblyopes indicate improvement in visual acuities of the amblyopic eye and binocular stereopsis without statistically significantly. CONCLUSIONS Amblyopic treatment has been profoundly demonstrated hopeful to amblyopes beyond the critical period of visual development. Our result showed that interocular shift of visual attention training was also effective in these age groups. Amblyopes beyond the critical period of visual development can advance visual acuity,especially stereopsis by interocular shift of visual attention training.