Effect of Photorefractive Keratectomy and Laser in situ Keratomileusis in High Myopia on logMAR Visual Acuity and Contrast Sensitivity

Abstract

Purpose: To compare effect of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) on contrast sensitivity (CS) and best corrected visual acuity (BCVA) in high myopia. Methods: 38 myopes (PRK) and 31 patients (LASIK) were examined before and 1, 3, 6, and 12 months postoperatively. Mean preoperative spherical equivalent was -8.0 ± 1.7D (PRK) and -9.2 ± 2.1D (LASIK). CS was tested on a computerized system of the Contrast Sensitivity 8010 Type at 6 spatial frequencies (0.74 and 29.55 c/deg), BCVA was measured on logMAR charts. Results: At 12 months postoperatively, mean spherical equivalent was -0.6 ± 1.0D (PRK) and -1.0 ± 0.8D (LASIK). Postoperative values of CS were significantly higher in the PRK group, except for spatial frequencies of 3.69 and 7.39 c/deg up to 3 months postoperatively. The initial significant decrease of BCVA lasted up to 6 months after PRK. In the LASIK group BCVA was not significantly different from its preoperative level at the 3-months follow-up. Conclusions: The significant improvement of CS after PRK suggest that PRK can improve quality of vision in eyes with high myopia. Although recovery of BCVA after LASIK was faster than after PRK, there may be a persistent decrease in CS.

The Effect of Diffuse Lamellar Keratitis on Visual Acuity and Contrast Sensitivity following LASIK

“… 17 , 18 Currently, transient or permanent decreases in CS after LASIK have been reported. 1 - 3 , 17 , 19 - 24 Although Moon and Tchah 25 reported no CS decrease in all spatial frequencies, Cho and Kim 26 described CS decrease in high spatial frequency up to 11 months postoperatively. Our study also showed a reduction of CS after LASIK up to six months in patients with DLK.…”

“…Since CS testing was introduced by Shade16 in 1956, CS has been widely accepted to provide more information about functional vision than Snellen visual acuity 17,18. Currently, transient or permanent decreases in CS after LASIK have been reported 1-3,17,19-24. Although Moon and Tchah25 reported no CS decrease in all spatial frequencies, Cho and Kim26 described CS decrease in high spatial frequency up to 11 months postoperatively.…”

Long-Term Results of Excimer Laser Surface Ablation with Smoothing for High Myopia

“…Additionally there is a reduced biomechanical effect with PRK and reduced risk of ectasia compared to LASIK [20]. Lastly, better contrast sensitivity in high myopes has been reported after PRK compared to LASIK [21]. Based on these factors and avoiding the attendant risks of flap creation, PRK for high myopia with a concomitant haze mitigating strategy is a reasonable surgical alternative to LASIK [22].…”