Abstract
Purpose To compare the binocular vision status of patients pre- and post-cataract surgery, and to investigate the risk factors for patients who develop binocular vision anomalies post-surgery. Methods A prospective study of patients (>= 50 years) who elected to undergo bilateral cataract surgery was implemented. A comprehensive binocular vision test battery including stereopsis, ocular alignment, fusional vergence, vergence facility, near point of convergence and the Convergence Insufficiency Symptom Survey (CISS) was administered before the first surgery and at the third visit after surgery on the second eye. A detailed diagnostic classification protocol was applied to identify the presence of binocular vision anomalies pre- and post-surgery. Results Seventy-three participants were included at baseline, 24 (33%) of whom were diagnosed with non-strabismic binocular vision anomalies (NSBVA), mainly convergence insufficiency (18/73, 25%). Fifty-one participants completed the post-operative evaluation, 17 (33%) of whom had NSBVA pre-surgery and 13 (26%) post-surgery (p = 0.48). There were a number of conversions from NSBVA to normal binocular vision and vice versa. Logistic regression showed that the adjusted odds ratio of pre-existing NSBVA diagnosis for predicting the risk of post-operative NSBVA was 6.37 (p < 0.01). There were no significant changes in most binocular vision measures post-surgery, except for a significant improvement in the CISS score (p < 0.01, Cohen's d = 0.83). Conclusions Binocular vision anomalies, especially convergence insufficiency, are prevalent in the age-related cataract population. Cataract surgery does not appear to be a significant risk factor for the development of new binocular vision anomalies. A pre-existing binocular vision anomaly is the main risk factor for predicting a post-operative binocular vision anomaly in this population.