The time-honored approach of patching may be less effective, especially in older children with amblyopia. Photo: Getty Images.

Amblyopia with eccentric fixation, especially when not diagnosed early, is a therapeutic challenge, as visual outcomes are known to be poorer than in cases of amblyopia with central fixation. Consequently, treatment after late diagnosis is often denied. Electronic monitoring of occlusion provides the chance to gain insight into age-dependent dose response, treatment efficiency and fixation shift in this rare group of pediatric patients. Based on electronic monitoring, a recent study quantified for the first time the reduction of treatment efficiency with increasing age in amblyopes with eccentric fixation.

The prospective pilot study examined amblyopes with eccentric fixation during 12 months of occlusion treatment. There were 12 participants with strabismus and combined amblyopia aged 2.9 to 12.4 years old. A team evaluated their visual acuity, recorded patching duration and determined their fixation with a direct ophthalmoscope. Dose-response relationship and treatment efficiency were calculated.

The median prescription of occlusion was 7.7 hours per day and the median daily received occlusion was 5.2 hours per day. At the end of the study, the median acuity gain was 0.6 log units and residual interocular visual acuity difference was 0.3 log units. There was neither a significant acuity gain nor a reduction in interocular visual acuity difference after the sixth month of treatment. Children younger than four years showed the best response with the lowest residual interocular visual acuity difference at the end of the study. Efficiency calculation showed an acuity gain of approximately one line from 100 hours of patching in the first 2 months and half a line after six months. There was a significant decline of treatment efficiency with age. Foveolar fixation was achieved after a median of three months. Three patients (>six years) did not gain central fixation.

“Despite some improvement in patients up to eight years, older patients showed significantly lower treatment efficiency,” the study authors concluded. “In younger patients with good adherence, despite poor initial acuity, central fixation and low residual interocular visual acuity difference could be attained after a median of three months. Hence, the necessity of early diagnosis and intensive occlusion should be emphasized.”

Mehmed B, Fronius M, Pohl T, et al. Electronically monitored occlusion therapy in amblyopia with eccentric fixation. Graefes Arch Clin Exp Ophthalmol. October 16, 2021. [Epub ahead of print].