# The influence of prior brief occlusion therapy on the outcome of later amblyopia treatment in cats

## TL;DR

This study in cats suggests that prior brief treatment of amblyopia may reduce the effectiveness of later treatment, possibly due to changes in neural plasticity.

## Contribution

The study introduces evidence that early treatment history affects later amblyopia recovery and proposes a 3-E protocol for improved treatment outcomes.

## Key findings

- Kittens with prior brief occlusion therapy showed less visual acuity recovery compared to those without prior treatment.
- The results suggest that prior visual history may influence neural plasticity and recovery potential in amblyopia.
- A proposed 3-E protocol (Early, Exact, Enduring) is suggested to optimize occlusion therapy outcomes.

## Abstract

Certain multi-centered randomized clinical trials of conventional treatment of children with amblyopia revealed greater improvement of the visual acuity of the amblyopic eye in patients that were never treated compared to those with a prior history of unsuccessful therapy. As a step toward a possible explanation for this phenomenon, this study investigated the influence of early prior brief treatment of amblyopia on the success of later treatment.

These experiments were conducted using the well documented feline model of deprivation amblyopia. Behavioral visual acuity thresholds were made by use of a jumping stand and a two-alternative forced choice procedure.

Six amblyopic kittens that received a very brief period of occlusion of the non-amblyopic eye prior to a much longer subsequent period of such occlusion exhibited less recovery of the visual acuity of the amblyopic eye (group mean 1.44 c/deg) compared to 7 control amblyopic animals that received only the second period of treatment (group mean 2.57 c/deg).

The results from this animal model indicate that prior visual history may impact the capacity for neural plasticity and thus the potential for recovery from amblyopia. From a clinical standpoint the data suggest adoption of a 3-E protocol to optimize the efficiency of occlusion therapy for amblyopia in which occlusion is initiated Early, applied in an Exact manner, and be Enduring in length.