[Vector analysis of astigmatism correction in femtosecond laser-assisted arcuate keratotomy for extreme astigmatism after penetrating keratoplasty].

Purpose: To study the results of femtosecond laser-assisted arcuate keratotomy in extreme astigmatism after penetrating keratoplasty, using a Ziemer LDVZ6 with a modified Lindstrom nomogram.

Design: Case series, retrospective study.

Method: Consecutive eyes that underwent femtosecond laser-assisted arcuate keratotomy between 2014 and 2019 in the Nantes University Hospital for extreme astigmatism after penetrating keratoplasty were included.

Results: Twenty-four eyes of 24 patients were included. The mean age was 53.3±12.2 years at the time of the arcuate keratotomies. Indications for penetrating keratoplasty were keratoconus in 66.7% of cases, herpes keratitis in 16.7% of cases, and corneal dystrophy in 16.7% of cases. The mean initial best corrected visual acuity was 0.36±0.23 logMar versus 0.26±0.15 logMar at the 3-month postoperative visit (P=0.04). At the postoperative visit, 54% (13/24) of eyes had improved best corrected visual acuity (BCVA), and 25% had no change in BCVA, with a mean cylinder reduction of 3.3 diopters. The mean preoperative topographic cylinder was 9.5±3.2 diopters versus 6.2±2.8 diopters postoperatively (absolute values; P<0.001), i.e. a 34.7% reduction in astigmatism. At the 3-month postoperative visit, 20.8% of eyes (5/24) had topographic astigmatism less than 3 diopters with a mean astigmatism reduction of 97±55% (range: 17; 201) using the Alpins method. No suppurative keratitis or endophthalmitis were observed. Twenty-one percent of patients underwent a second arcuate keratotomy after 3 to 6 months due to insufficient refractive results.

Conclusion: Development of new nomograms designed for extreme astigmatism after penetrating keratoplasty would enhance the precision and reproducibility of femtosecond laser-assisted arcuate keratotomy in these cases.