To the Editor Pineles et al1 studied binocular summation, defined as the improvement in visual acuity (VA) using binocular vision compared with the better eye alone. The authors reported that strabismus surgery was associated with average improvements in binocular summation of 0.8 letters for VA and of 1.5 and 2.6 letters for VA at 2.5% and 1.25% contrast, respectively.1 The interpretation of the results might be aided by additional information. A more positive binocular summation value can result from better binocular vision, or from worse vision in the better eye. Consider a patient with a preoperative VA of 20/20, both binocularly and in the better eye. If the postoperative VA decreases to 20/25 binocularly and to 20/30 in the better eye, the patient will be reported to have an improvement in binocular summation of 1 line, despite the fact that the patient does not see as well. To address this possibility, it would be of value if the authors could report the mean preoperative and postoperative binocular and better-eye VA and contrast VA as well as the paired t-test value.
Leffler CT, Janot AC. Postoperative Visual Acuity Should Be Reported in Studies of Binocular Summation. JAMA Ophthalmol. 2015;133(8):968-969. doi:10.1001/jamaophthalmol.2015.0939