Wavefront-guided photorefractive keratectomy for myopia and myopic astigmatism.

PURPOSE: To evaluate the results of wavefront-supported customized ablation (WASCA) in eyes treated with photorefractive keratectomy (PRK) to correct spherical myopia and myopic astigmatism. METHODS: One-hundred fifty eyes of 104 patients (mean age 33.4 +/- 4.4 years) were included in the study. An Asclepion Shack-Hartmann wavefront aberrometer was used to assess lower and higher order refractive aberrations of eyes, and customized PRK treatments were carried out using the Asclepion-Meditec MEL 70 G-Scan excimer laser. Follow-up time was 6 months. RESULTS: The mean preoperative spherical equivalent refraction was -4.02 +/- -1.04 D, and mean uncorrected visual acuity (UCVA) was 0.06 +/- 0.02. Postoperatively, mean UCVA was 1.04 (better than 20/20), mean best spectacle-corrected visual acuity was 1.22 (20/16), and average spherical equivalent refraction was -0.12 D; 98.6% (148 of 150 eyes) were within +/-0.50 D of intended refraction, and 100% were within +/-1.00 D. Concerning safety, in 71.1% of eyes (107 of 150) BSCVA was the same as preoperatively, and in 8.2% (11 of 150) it increased by two or more Snellen lines. None of the eyes lost two or more lines of BSCVA. The root mean square value for higher order aberrations increased 1.4 times following PRK. CONCLUSIONS: WASCA-guided PRK was efficacious, safe and predictable; BSCVA may be improved by the WASCA method compared to results achievable with a traditional PRK technique, in spite of an increase in the root mean square value for higher-order aberrations.

First results with wavefront-guided photorefractive keratectomy for hyperopia.

PURPOSE: To compare the results of traditional laser photoablation and wavefront-supported customized ablation (WASCA) in hyperopic photorefractive keratectomy (H-PRK). METHODS: This was a prospective study, comparing two treatment groups, each comprising 40 eyes of 20 patients. Wavefront aberrations were examined using a Shack-Hartmann aberrometer. Preoperative refraction was similar in the two groups; in the traditional H-PRK group (Group 1) it was +3.10 +/- 0.85 D, and in the WASCA-guided group (Group 2) it was +2.90 +/- 0.80 D. H-PRK was performed with the Asclepion-Meditec MEL 70 flying-spot excimer laser. The follow-up time was 6 months. RESULTS: In Group 1, mean postoperative refraction was +0.14 +/- 0.24 D, and in Group 2, -0.10 +/- 0.25 D; mean uncorrected visual acuity was 0.92 +/- 0.16 in Group 1 and 0.95 +/- 0.18 in Group 2. Mean best spectacle-corrected visual acuity was 0.96 +/- 0.04 in Group 1 and 1.06 +/- 0.13 in Group 2. In Group 1, 67.5% (27 of 40 eyes), and in Group 2, 85% (34 of 40 eyes) were within +/-0.50 D of target refraction. Regarding change of spectacle-corrected visual acuity in Group 1, 5% (2 of 40 eyes), and in Group 2, 20% (8 of 40 eyes) gained one Snellen line compared to the preoperative; in Group 1, 10% (4 of 40 eyes), and in Group 2, 12.5% (5 of 40 eyes) lost two Snellen lines. In Group 2, the root mean square value for the higher order aberration increased from the initial 0.134 to 0.257 microm at 6 months after surgery. CONCLUSIONS: WASCA-guided hyperopic-PRK treatment was found to be safe and predictable. The results were better than those achieved with traditional PRK performed using the same flying-spot type excimer laser.