[Comparison of higher-order aberrations in conventional versus customized ablation for photo refractive keratectomy]

ABSTRACT

To compare visual outcomes and changes in high-order aberrations [HOAs] following conventional versus customized photorefractive keratectomy [PRK]. In this clinical trial, 58 eyes of 29 patients underwent myopic PRK using the Technolas 217Z excimer machine. After comprehensive evaluation for refractive surgery, one eye of each participant randomly received conventional ablation [group 1] while customized treatment was performed in the fellow eye [group 2]. Changes in postoperative visual acuity, cycloplegic refraction, and contrast sensitivity function [CSF], HOAs and subjective complaints of halos and glare were compared between the two groups. Mean subject age was 26.7 +/- 6.0 years. Mean preoperative cycloplegic spherical equivalent refractive error and refractive astigmatism were -4.92 +/- 1.6 0 and 0.91 +/- 1.0 0, respectively. There was no significant difference between the two groups in terms of preoperative HOAs and CSF. Mean follow-up period was 8.1 +/- 3.3 months. After the operation, total HOAs for 4 mm pupil was increased by 0.24 +/- 0.19 pm in group 1 and by 0.31 +/- 0.21 pm in group 2 [P<0.001]. Corresponding figures for 6 mm pupil were 0.34 +/- 0.23 [range -0.08 to 0.75] and 0.52 +/- 0.32 [-0.04 to 1.43] pm respectively [P=0.03]. The increase in postoperative HOAs was statistically significant in group 2 in the 6 mm zone [P=0.03] but not in the 4 mm zone [P=0.26]. CSF was reduced in both groups, but there was no significant difference between the study groups in terms of postoperative CSF and subjective complaints. HOAs significantly increased after PRK using conventional and customized ablation. The increase in HOAs after customized ablation was significantly greater than that after conventional ablation