Outcomes for Mixed Cylinder LASIK With the MEL 90^® Excimer Laser

To report the outcomes of LASIK for mixed cylinder using the Triple-A ablation profile with the MEL 90 excimer laser (Carl Zeiss Meditec, Jena, Germany).

This was a retrospective analysis of all eyes treated by LASIK for mixed cylinder using the Triple-A ablation profile with the MEL 90 laser between July 2013 and October 2016. Patients were observed for 1 year after surgery. Standard outcomes analysis and vector analysis by the Alpins method were performed.

The database review identified 105 eyes (82 patients) treated by LASIK for mixed cylinder using the MEL 90 laser. Mean age was 40 ± 11 years (range: 18 to 65 years). Mean attempted spherical equivalent was +0.30 ± 0.90 diopters (D) (range: -2.30 to +1.75 D). Mean cylinder was -2.93 ± 1.47 D (range: -0.75 to -7.00 D). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 81% of eyes. Postoperative uncorrected distance visual acuity was 20/20 or better in 69% and 20/25 or better in 86% of eyes. Mean postoperative spherical equivalent relative to the intended target was -0.21 ± 0.38 D (range: -1.25 to +1.13 D), with 83% within ±0.50 D. Mean postoperative cylinder was -0.57 ± 0.41 D (range: 0.00 to -1.75 D). Geometric mean was 1.12 for the correction index and 0.25 for the index of success. For angle of error, the arithmetic mean was -0.6° ± 4.2° (range: -13.5° to 9.5°) and the absolute mean was 2.9° ± 3.0° (range: 0.0° to 13.5°). There was loss of one line of CDVA in 3% of eyes and no eyes lost two or more lines CDVA. There was a small increase in contrast sensitivity after surgery at 3, 6, 12, and 18 cycles per degree (P < .05).

One-year outcomes of LASIK using the MEL 90 laser for mixed cylinder up to -7.00 D demonstrated excellent efficacy, safety, and predictability. Vector analysis found a 12% overcorrection in magnitude of refractive cylinder. Given the high accuracy for angle of error, a nomogram could be applied to reduce the over-correction and further improve the uncorrected distance visual acuity outcomes. [J Refract Surg. 2018;34(10):672-680.].