Significance of binocular fusion in enhancing visual acuity during amblyopia treatment.

Background: Currently, the exploration of amblyopia treatment methods is gradually shifting to the restoration of binocular visual perceptual function. Binocular fusion function, as an important component of binocular visual function, mainly reflects the patient's ability to integrate the signals received from both eyes. In this study, we investigated the relationship between binocular fusion function and improvement in visual acuity during amblyopia treatment.

Methods: A retrospective analysis was conducted on a cohort of patients with amblyopia, aged 3-14 years old, who visited an outpatient clinic in Shenzhen Eye Hospital between May 2021 and January 2023. The investigation included 105 patients (210 eyes) with isometropic or anisometropic amblyopia. All participants underwent cycloplegic refraction examination and binocular fusion function measurement. All patients underwent standard amblyopia treatment, and those with the best-corrected visual acuity (BCVA) of 0.6 or higher in the amblyopic eye of both eyes received binocular fusion training using a computer platform.

Results: A statistically significant negative correlation (-0.263, P=0.007) was observed between the absolute difference in binocular BCVA and binocular fusion function at the start of treatment (baseline). Linear regression analysis revealed that the improvement in BCVA in the amblyopic eye exhibited correlations with several factors, including the baseline binocular BCVA difference, baseline BCVA of the amblyopic eye, improvement in binocular fusion function, and the number of fusion training sessions (regression coefficients: -0.463, -0.771, 0.007, and 0.063, respectively; all P<0.05). Two patterns of binocular fusion function development during treatment were identified using group-based trajectory modeling (GBTM): the slow growth pattern and the rapid growth pattern. The results of a multivariate logistic regression model indicated a statistically significant link between fusion training and the development pattern of binocular fusion function [odds ratio (OR): 5.219, 95% confidence interval (CI): 2.045-13.323].

Conclusions: Enhancing binocular fusion function may result in an improvement of BCVA in the amblyopic eye of patients with amblyopia. The frequency of binocular fusion training is crucial for rapid improvement in binocular fusion function.