Comparison of optical quality metrics to predict subjective quality of vision after laser in situ keratomileusis

Abstract

PURPOSE: 

To compare wavefront-derived metrics to predict subjective quality of vision after laser in situ keratomileusis (LASIK) for myopia.

SETTING: 

Department of Ophthalmology, Goethe University, Frankfurt am Main, Germany.

METHODS: 

One month postoperatively, wavefront sensing was performed and overall subjective quality of vision assessed under 3 lighting conditions (photopic, high mesopic, low mesopic) with a questionnaire. Four wavefront-error representations were computed for a pupil diameter of 6.0 mm and individual physiological pupil diameters at 0.4 lux: (1) the visual Strehl ratio based on optical transfer function (VSOTF), (2) the root-mean-square (RMS) value of Zernike orders 2 to 5 (total RMS), (3) higher-order aberration (HOA) RMS, and (4) a wavefront-error breakdown into the RMS of lower-order aberrations, coma, spherical aberration, and remaining HOA. The impact of the postoperative wavefront error on subjective quality of vision was calculated using linear regression analysis.

RESULTS: 

Fifty-six eyes (29 patients) were included. The ability of wavefront error–derived metrics to predict subjective quality of vision was limited. The VSOTF, calculated for the best-corrected eye, showed the highest predictability. Calculation of wavefront error for individual physiological pupil diameters did not improve predictive ability of the metrics. Eyes with a high theoretical retinal-image quality had a high subjective quality of vision, and eyes with a low subjective quality of vision had a low theoretical image quality.

CONCLUSIONS: 

Postoperative wavefront error had limited influence on the subjective quality of vision. Postoperative retinal image quality should be kept as high as possible to provide good subjective quality of vision.