Prospective Randomized Controlled Trial Comparing Optical Quality After Myopic Small-Incision Lenticule Extraction, LASIK, and PRK: Impact on Binocular Vision
This randomized controlled study addresses two important questions related to visual performance of myopic eyes following refractive surgery. Firstly, to compare the optical quality following bilateral refractive surgery and secondly, to compare the impact of induced ocular aberrations on sensory and motor visual performance following different refractive surgeries.
A total of 106 patients with myopic astigmatism were randomized to undergo either femtosecond LASIK (40), SMILE (40) or PRK (26). PRK and LASIK were performed on the Technolas 217z excimer laser platform and the SMILE was performed on the Visumax femtosecond laser system. Preoperative and postoperative 1 week, 1 month, 3 months and 6 months was analyzed. The main outcomes reported in this study were best corrected high contrast and low contrast acuity, manifest objective refraction, ocular aberrations measured using the IMAGINE EYES Irx3 aberrometer and stereopsis using random dot stereoacuity. Retinal Image quality was compared among three categories before and after surgery using image quality metrics.
At 6 months postop, the spherical equivalents were +0.14±0.05, +0.37±0.03, +0.02±0.01 in the LASIK, PRK, and SMILE groups respectively. (p>0.001) High contrast unaided distance acuity (UDVA) was comparable across the groups, while low contrast UDVA decreased in both LASIK and PRK (0.1 vs. 0.2) while it was better following SMILE (0.1 vs. 0.0). Higher-order aberrations increased significantly in PRK (0.25±0.02µ vs. 0.6±0.03µ, p<0.001) and LASIK (0.27±0.01µ vs. 0.6±0.02µ, p<0.001) but were not significantly different following SMILE (0.24±0.3µ vs. 0.28±0.4µ, p=0.11). Stereo acuity was significantly better after SMILE (49.39±5.49 vs. 19.90±1.72 sec arc, p<0.001) but showed a decrease following LASIK (45.55±3.28 vs. 55.72±1.75 sec arc, p<0.05) and PRK (47.05±3.95 vs. 64.02±2.43 sec arc, p<0.01)
LASIK, PRK and SMILE resulted in accurate correction of refractive error and comparable high contrast UDVA but low contrast UDVA was reduced to a lesser degree following SMILE. Patients undergoing SMILE had lesser induced aberrations and had better stereoaculty following surgery compared to either LASIK or PRK.