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Published on: September 20, 2024
Laser in situ keratomileusis for primary and secondary mixed astigmatism
George J C Jin1, Kevin H Merkley, W Andrew Lyle
1The Eye Institute of Utah, 755 East 3900 South, Salt Lake City, UT 84107, USA. georgejin@hotmail.com
Purpose:
To evaluate and compare the efficacy, predictability, and safety of LASIK in the correction of primary and secondary mixed astigmatism after previous LASIK surgery.
Design:
Retrospective, comparative case series.
Methods:
The retrospective study included 118 eyes having LASIK with the LADARVison 4000 excimer laser (Alcon Surgical, Orlando, Florida) to correct mixed astigmatism. The eyes were divided into two groups: in group A (n = 64), LASIK was for primary mixed astigmatism and in group B (n = 54), LASIK was for secondary mixed astigmatism. Mean follow-up was 10.6 +/- 5.90 months.
Results:
Overall, the postoperative UCVA was 20/20 in 51% of eyes and 20/40 or better in 97% of eyes at the last visit. The mean refractive cylinder was -2.18 +/- 0.94 D preoperatively and -0.56 +/- 0.56 D postoperatively. Sixty-one percent of eyes had a refractive cylinder of 0.50 D or less. One eye lost 2 lines of BSCVA (0.8%). None of the eyes had postoperative BSCVA worse than 20/25. The difference of preoperative cylinder was significant between group A and group B (P = .000). However, there was no statistical difference of postoperative refraction and UCVA between these two groups. At 12 months, the mean vector magnitude achieved was 93% of intended cylinder correction with a mean angle of error of -3.0 +/- 16 degrees.
Conclusions:
LASIK is a safe, effective, and predictable procedure to treat both primary and secondary mixed astigmatism. Nomogram adjustment with spherical and astigmatism components individually may improve refractive outcomes.
