Low Contrast Acuity, Contrast Sensitivity and Higher-order Aberration Outcomes following Custom LASIK

Abstract

Abstract: : Purpose: To examine changes in low contrast acuity (LC BCVA), contrast sensitivity (CS) and higher-order aberrations (HO RMS error) following a customised LASIK procedure. Methods: LASIK was performed on 156 myopic eyes (79 patients) using the LADARVision® laser coupled with the CustomCornea® Measurement Device. Preoperative sphere was -3.02±1.31D (range –0.25 to –5.75D) with mean cylinder –0.70±0.70D (range 0 to –4.00D). LC BCVA was measured using ETDRS LC charts and CS using the VectorVision^TM CSV1000 at 4 spatial frequencies. A CS change >0.3 log units (> 2 levels) at ≥ 2 spatial frequencies was considered clinically significant. HO RMS was measured with a Hartmann-Shack wavefront sensor. Wave aberrations were described as Zernike polynomial expansions. Root Mean Square wavefront error (RMS) was used as the optical quality metric. Results: 6 month myopic results: LC BCVA 99% ≥ 20/40, 96% ≥ 20/32, 74% ≥ 20/25, 27% ≥ 20/20. The change in HO RMS error was significantly correlated (r=0.92, p<0.05) with the change in coma. The change in HO RMS error was poorly correlated with changes in LC BCVA or any of the 4 CS spatial frequencies (r<0.50). Conclusions: Myopes experienced excellent quality of vision outcomes as determined by measures of LC BCVA and CS. There is a strong association between the change in HO RMS error and the change in coma, however only weak associations were found between changes in visual function and HO RMS error. Funding was provided by Alcon.  

Keywords: refractive surgery: LASIK • refractive surgery: optical quality • contrast sensitivity