The Characteristics of Quick Contrast Sensitivity Function in Keratoconus and Its Correlation with Corneal Topography.

Abstract

To characterize quick contrast sensitivity function (qCSF) in keratoconus and its correlation with corneal topographic parameters. Patients with keratoconus (n = 120) who visited the Fudan Eye and ENT Hospital between April and June 2021 were enrolled in our study. A total of 215 eyes were subdivided into three groups according to maximum keratometry (Kmax): Group1 (Kmax ≤ 48D, 74 eyes), Group2 (48D < Kmax ≤ 55D, 64 eyes), and Group3 (Kmax > 55D, 77 eyes). Manifest refraction, best corrected distance visual acuity (BCVA), corneal topography, and the qCSF test were examined. Intergroup comparisons and correlations among various corneal topographic parameters and qCSF were analyzed. Significant differences in the area under the logCSF (AULCSF) and CSF Acuity among the three groups were found, which decreased with an increase in Kmax. Contrast sensitivity (CS) between spatial frequencies of 3.0 to 18.0cpd was significantly different (all P < 0.05) between Groups1 and 2. The CS at all spatial frequencies was significantly different (all P < 0.05) between Group3 and other two groups. At 3.0-18.0cpd, CS decreased significantly (all P < 0.05) in Groups1-3. Manifest refraction and topographic indices correlated significantly with qCSF parameters (all P < 0.05). Multivariable linear regression analysis showed that cylindrical refraction, logMAR BCVA, and index of surface variance had good predictive values for AULCSF and CSF Acuity. The use of qCSF test can serve as a feasible tool to evaluate visual quality and severity of keratoconus, since changes in CS significantly correlated with keratoconus severity.