Analysis of stereopsis and fusion in school-aged children with reduced visual acuity due to refractive error

PURPOSE: In patients with strabismus, the stereopsis and Worth 4-dot (W4d) tests have often been used to evaluate whether sensory fusion is achieved. However, if patients face difficulties undergoing the Titmus or W4d test because of poor visual acuity (VA) due to refractive error abnormalities, the results of these tests cannot be appropriately interpreted. Therefore, we evaluated the correlation between distance uncorrected VA (UCVA) and sensory status in children with reduced VA due to refractive error abnormalities to identify the effects of refractive errors on sensory test results. METHODS: We retrospectively reviewed the medical records of 195 children with reduced VA with VA improvement ≥ 20/25, Titmus stereoacuity ≤ 50 arcsec, and fusion in the W4d result after refractive error correction with spectacles. We evaluated the correlation between distance UCVA in logMAR and sensory status measured by the near Titmus stereotest and distance W4d test. Additionally, the minimum required UCVA for interpreting Titmus or W4d results was assessed using a receiver operating characteristic (ROC) curve. RESULTS: The UCVA showed a marginal but non-significant correlation with Titmus stereoacuity (p = 0.053) and a significant correlation with fusion in W4d (p < 0.001). The ROC curve analysis showed an optimal cut-point value of VA required for interpreting the results of W4d test as 0.3 logMAR (20/40 in Snellen acuity). CONCLUSIONS: Correcting refractive error in advance may help appropriately interpret sensory status in school-aged children with reduced VA due to refractive error abnormalities.