A brief effective screening protocol for identifying cataract patients with binocular vision anomalies

Abstract

Background: To compare the effectiveness of a brief binocular vision screening protocol to a comprehensive examination for detecting binocular vision anomalies before and after cataract surgery.

Methods: A comprehensive binocular vision test battery as a gold standard were administered on recruited patients before the first surgery and at the third visit after surgery on the second eye. A receiver operating characteristic (ROC) curve was plotted to illustrate the diagnostic ability of each test. In addition, a univariate logistic regression analysis was performed to further determine the contribution of each preoperative test to the prediction of pre- and post-surgical binocular vision anomalies.

Results: Significant differences were shown for the difference in phoria from distance to near measured by the cover test (Area Under Curve [AUC] = 0.96, P < 0.01), step vergence testing of positive fusional vergence at distance (AUC = 0.71, P < 0.01) and near (AUC = 0.77, P < 0.01). The other tests did not show statistically significant differences. The ROC curve generated by combining the difference in distance and near phoria with positive fusional vergence at both distance and near demonstrated a more robust measure of diagnostic accuracy. (AUC = 0.98, P < 0.01).

Conclusion: Distance and near phoria difference measured by cover test has similar effectiveness as a comprehensive binocular vision testing protocol for the diagnosis of binocular vision anomalies. Distance and near positive fusional vergence measured by step vergence testing also have significant predictive value. A combination of the two tests is an outstanding screening protocol for binocular vision anomalies before cataract surgery.

Trial registration: The study was registered at ClinicalTrials.gov (NCT03592615, Date of registration: July 19, 2018).

Keywords: Age-related; Binocular vision anomaly; Cataract; Screening protocol.

Fig. 1

ROC curve showing the diagnostic ability of A each binocular vision test, B a combination of cover test and positive fusional vergence. (Note: the source of the curve in the figure was sorted by AUC from large to small; CT_DIFF: cover test measured lateral phoria difference between distance and near; BO_NEAR_BREAK: break point of positive fusional vergence at near using base-out prism; BO_DIST_BREAK: break point of positive fusional vergence at distance using base-out prism; BI_DIST_BREAK: break point of negative fusional vergence at distance using base-in prism; BI_NEAR_BREAK: break point of negative fusional vergence at near using base-in prism; VF_NEAR: vergence facility at near; VF_DIST: vergence facility at distance; NPC BREAK: break point of near point of convergence; CISS: convergence insufficiency symptom survey score; CT: cover test; PFV: positive fusional vergence; Reference line: the line with a AUC of 0.5 that indicates a test no better than chance; *: indicating a statistically significant difference from the reference line.)