Combined Corneal Topography and Corneal Wavefront Data in the Treatment of Corneal Irregularity and Refractive Error in LASIK or PRK Using the Carl Zeiss Meditec MEL 80 and CRS-Master

Abstract

To assess the efficacy, safety, and accuracy of TOSCA II (Topography Supported Custom Ablation) treatments for the correction of high corneal aberrations and refractive error following previous ocular surgery. Forty-eight eyes of 32 patients were included for study. Indications for TOSCA II treatment included small optical zone, decentered ablation, subjective visually significant higher order aberrations, and irregularly irregular astigmatism induced by LASIK, photorefractive keratectomy, radial keratotomy, conductive keratoplasty, cataract surgery, and deep lamellar keratoplasty. An ablation profile based on corneal topography data and corneal wavefront and manifest refraction was created using the CRS-Master software (Carl Zeiss Meditec) to treat corneal irregularity and refractive error simultaneously. Postoperative assessments were performed at 1 week and 1, 2, 3, 6, and 12 months. Mean attempted spherical equivalent refraction (SE) was -1.12 +/- 1.97 diopters (D) (range: +1.13 to -10.50 D). Mean attempted cylinder correction was 1.34 +/- 1.65 D (range: 0.00 to 7.75 D). Median age was 38 years (range: 19 to 68 years). Median follow-up was 9.4 months. Accuracy: mean deviation from the intended SE correction was -0.19 +/- 0.94 D, 60% of eyes were within +/- 0.50 D and 77% of eyes were within +/- 1.00 D of the intended SE. Cylinder: the correction ratio was 1.49 +/- 0.85 and the error ratio was 0.87 +/- 0.69. 56% of eyes achieved uncorrected visual acuity of 20/20 or better and 88% achieved 20/40 or better. 34% of eyes gained one or more lines of best spectacle-corrected visual acuity, 15% lost one line, and no eye lost two or more lines. Contrast sensitivity: for the subset of eyes with below normal contrast sensitivity preoperatively, there was a statistically significant improvement in contrast sensitivity at 3 cycles per degree (cpd), 6 cpd, and 12 cpd (P < .05). Stability: the average change in refraction between 3 months and 1year was +0.38 +/- 0.30 D. Higher order aberrations: the average higher order root-mean-square decreased by 21% and the average spherical aberration decreased by 41%. The MEL 80 CRS-Master TOSCA II software appears to be an effective treatment for decentrations, optical zone enlargement, and reduction of higher order aberrations. The refractive outcome was satisfactory after one treatment.