Nonpenetrating femtosecond laser intrastromal astigmatic keratotomy in eyes having cataract surgery

Abstract

To describe the effect of femtosecond laser intrastromal astigmatic keratotomy (AK) performed during cataract surgery. Moorfields Eye Hospital, London, United Kingdom. Prospective case series. This study comprised patients having laser cataract surgery with concurrent astigmatism management by intrastromal AK. All eyes had greater than 0.7 corneal diopter (D) cylinder. An intrastromal AK nomogram with 8.0 mm diameter paired symmetric limbal centered arcs was used. Corneal keratometry was measured preoperatively and 1 month postoperatively using a KR8100PA topographer-autorefractor. Astigmatic analyses were performed using the Alpins method considering 3 vectors-target induced astigmatism (TIA), surgically induced astigmatism (SIA) and difference vector (DV)-and calculation of coupling measures. In all, 196 eyes of 133 patients were analyzed. The mean TIA (equivalent to preoperative corneal cylinder) was 1.21 D ± 0.42 (SD) (range 0.75 to 2.64 D) and the mean SIA was 0.74 DC ± 0.40 (range 0.00 to 2.86). The mean difference vector was 0.74 ± 0.38 D (range 0.00 to 2.25 D). The mean correction index was 0.63 ± 0.32 (range 0.00 to 1.93), indicating that the mean astigmatism correction was 63%. Fourteen eyes (7.1%) and 7 eyes (3.6%) had an astigmatism correction of greater than 100% and greater than 120%, respectively. Overall 0%, 48.5%, and 51.5% of eyes had 0.50 D or less, 1.0 D or less, or greater than 1.0 D, respectively, preoperatively compared with 32.1%, 85.7%, and 14.3%, postoperatively. There were no cases of corneal endothelial perforation or inadvertent placement within the visual axis. The intrastromal AKs were easily programmed as an integral part of laser-assisted cataract surgery without additional cost, significantly reduced corneal cylinder, and appeared to be safe through 1 month of follow-up. Dr. Day was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology. Dr. Stevens has been a consultant to Optimedica Inc., now part of Abbott Medical Optics.