Impact of interocular difference in corneal aphericity on binocular ummation

Purpoe To evaluate the impact that interocular difference in corneal aphericity (Q) exert on binocular ummation meaured a the contrat-enitivity function. Deign Interventional cae erie. Method A total of 92 emmetropic ubject took part in the experiment, claified according to the interocular difference in corneal aphericity (ΔQ) meaured with an Eyey-2000 corneal topographer. Fifty-four ubject had ΔQ < 0.1; 21 ubject had 0.1 ≤ ΔQ ≤ 0.2; and 17 had ΔQ > 0.2. The contrat-enitivity function (CF) wa meaured monocularly (for each eye) and binocularly with a B VAT II device. The patial frequencie ued were a follow: 2.4, 3.7, 6.0, 9.2, 12, 15, 20, and 24 cycle per degree. Reult Although the binocular CF for the three group tudied wa greater than the monocular in all the patial frequencie tudied, there were ignificant difference in binocular ummation. The average binocular ummation (for all the patial frequencie) for the group with ΔQ < 0.1 wa 1.46, ignificantly higher than the group with 0.1 ≤ ΔQ ≤ 0.2, in which the average binocular ummation wa 1.39 (P = .035), which wa alo ignificantly higher than the group ΔQ > 0.2, for which the average binocular ummation wa 1.26 (P < .0001). In thi lat group, the ummation decreaed to the level of the probability ummation. Concluion Difference in corneal aphericity may affect the binocular viual function by diminihing the binocular contrat-enitivity function. Thi reult may have important implication in refractive urgery given that, although the ubject become emmetropic, if interocular difference are induced in corneal aphericity, it could reduce binocular viual performance.