Abstract
Purpose :
To compare the changes in refractive error and keratometry (K) in wavefront guided (WFG) LASIK and WFG photorefractive keratectomy (PRK) for correction of myopic refractive errors.
Methods :
A retrospective analysis of 334 eyes (170 patients) with manifest refractive spherical equivalent (MRSE) of -6.21 D ± 2.78 D (range: -12.13 D to -1.25 D) who underwent WFG Lasik, and 334 eyes (167 patients) with MRSE of -4.08 D ± 1.97 D (range: -8.75 D to -0.63 D) who underwent WFG PRK was performed. Outcome measures were changes in keratometry measurements taken with a full gradient corneal topographer and corresponding refractive changes compared preoperatively and at 6 months postoperatively. A correlation analysis was performed to determine the relationship between changes in refractive error (ΔSE) and changes in keratometry (ΔK). Ratio (ΔK/ΔSE) of change in keratometry (ΔK) to change in refractive error (ΔSE) was calculated and compared.
Results :
A strong negative correlation (LASIK: r = -0.897 (ΔSE vs ΔK), and PRK: r = -0.903 (ΔSE vs ΔK), p<0.0001 for both) was seen between the change in refraction and change in average K for both. The mean ratio for ΔK and ΔSE was -0.78±0.28 for LASIK and -1.03±0.52 for PRK. A larger ratio (ΔK/ΔSE) for the WFG PRK compared to the WFG LASIK (ratio difference of 0.25 with 95% CI of (0.19, 0.31), p<0.0001) was found. WFG PRK required more corneal flattening for a given change in refractive error when compared to WFG LASIK. The accuracy of intended versus achieved MRSE outcomes at 6 months indicate good accuracy of treatment per MRSE outcomes (LASIK, slope: 0.99, r=0.988, p<0.001 and PRK, slope:1.04, r=0.975, p<0.001).
Conclusions :
The refractive outcomes after both LASIK and PRK were comparable with good predictability at correcting myopia. However, WFG LASIK measurements showed a smaller amount of corneal flattening for a given degree of myopic refractive correction compared to WFG PRK.
This is a 2021 ARVO Annual Meeting abstract.