Optical Quality of Ten Years following Photorefractive Keratectomy for Myopic Eyes

Abstract

 

Purpose:

 

To investigate the optical quality with a ten years follow-up after photorefractive keratectomy (PRK) for low to moderate myopia.

 

Methods:

 

24 patients (45 eyes) underwent PRK using the NIDK EC-5000 excimer laser platform with low to moderate refractive powers(mean, -4.92±1.18D). Three control-matched groups were set: 36 eyes with Epi-LASIK surgery, which represents the surface ablation, and 30 eyes in LASIK group which represents lamella ablation, and those preoperative data. Wavefront aberrations were measured and calculated for a 6-mm pupil using a Hartmann-Shack sensor for the group10 years with PRK and preoperatively and 4 to 6 months after Epi-LASIK and LASIK procedures.

 

Results:

 

On average, PRK induced a significant (P=0.00) 2.3 -fold increase in the HOA RMS at 10 years after surgery compared to matched preoperative level. The main contribution was the increasing (3.5-fold) of spherical aberration and (3.1-fold) spherical-like aberrations (S₄). Moreover, spherical aberration (Z₁₂) showed a statistically higher increase (P=0.02) in 10 years group, and followed by post-LASIK and post-Epi-LASIK groups, which displayed the similar characters as those of the spherical-like aberrations. However, there was no significant difference of the postoperative coma-like aberrations (S₃) between the 3 types of surgery, or between long and short time postoperatively. In addition, from HOA, it showed no difference between different types of surface ablation (PRK and Epi-LASIK), no matter their follow-up periods were different, and the significant difference focused on different types of ablation (lamella and surface ablation).

 

Conclusions:

 

(1) Refractive surgery induces important amounts of the HOAs, even for long term. (2) The largest increase occurs for spherical and spherical-like aberrations in eyes at 10 years post-PRK, both rising by more than 3 times. (3) The 3rd order aberrations showed no significant difference in any postoperative state or any ablation types.  

 

Keywords: aberrations • refractive surgery • refractive surgery: optical quality