Effects of decentration of photorefractive keratectomy on the induction of higher order wavefront aberrations.
OBJECTIVE
To evaluate the effects of ablation decentration on the induction of higher order wavefront aberrations (HOAs) in active eye-tracker-assisted myopic photorefractive keratectomy (PRK) using the VISX STAR S4 laser with ActiveTrak (Abbott Medical Optics [AMO]).


METHODS
Ninety-four myopic eyes (53 patients) were divided into three groups according to ablation decentration (group 1, ≤0.15 mm, 20 eyes; group 2, >0.15 to ≤0.30 mm, 54 eyes; and group 3, >0.30 mm, 20 eyes). The distances of ablation centers from the centers of the entrance pupils were analyzed using corneal topography. Wavefront errors were measured preoperatively and at 6 months after PRK using a VISX WaveScan aberrometer (AMO). Statistical analysis was performed to assess the influence of ablation decentration on PRK-induced HOAs.


RESULTS
The mean decentration was 0.23±0.10 mm (range: 0.04 to 0.52 7 mm). The magnitude of all HOAs was significantly increased at 6 months postoperatively (P<.05). Increases in PRK-induced HOAs including total HOA, coma, and spherical aberration were significantly different among the three groups (P<.05). Statistically significant differences were noted between pairs of data in group 1 versus group 3 for total HOA (P=.015), coma (P=.038), and spherical aberration (P=.038), and group 2 versus group 3 for coma (P=.049).


CONCLUSIONS
Ablation decentration >0.30 mm from the center of the entrance pupil was associated with greater induction of total HOA, coma, and spherical aberration after PRK, as compared with ablation decentration <0.15 mm. In addition, ablation decentration has a more significant influence on coma-inducing effects.
Lee
Sang-Bumm
SB
Department of Ophthalmology, Yeungnam University College of Medicine, Daegu, Korea. sbummlee@med.yu.ac.kr
Hwang
Bo-Sung
BS
Lee
Junyeop
J
D057128:Aberrometry; D000328:Adult; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration / Q000209:etiology*; D005260:Female; D019466:Glare; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D009887:Ophthalmoscopy; D018903:Photorefractive Keratectomy / Q000009:adverse effects*; D011680:Pupil / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult