Use of Femtosecond Laser Technology to Reduce Astigmatism at the Time of Cataract Surgery
Purpose
Astigmatic keratotomy (AK) is a simple and effective procedure commonly used in corneal refractive surgery to manage astigmatism. For many years, limbal relaxation incisions (LRIs) have been made with a free-hand approach using various depths and arc lengths based on surgeon technique. Our aim is to evaluate the use of laser arcuate incisions at the time of femtosecond laser-assisted cataract surgery to reduce corneal astigmatism.
Methods
This is a retrospective chart review of 42 eyes with pre-operative corneal astigmatism that underwent femtosecond laser-assisted cataract surgery (Catalys, AMO) and received concurrent anterior-based, 80% ablation depth, 9 mm OZ, corneal arcuate incisions created by the femtosecond laser. Primary outcome measures include: 1) comparison of intended axis vs. actual axis of AK incisions 2) post-operative corneal astigmatism 3) effect of modifications to Donnenfeld’s LRI nomogram on achieved astigmatism correction.
Results
Our data show that the intended axis of AK incisions is not significantly different from the actual axis of AK incisions. The post-operative corneal astigmatism is significantly reduced with the use of laser-created AK incisions. We found the need to progressively add more arc length from the recommended 30% reduction based on the LRI nomogram. Our data support a more aggressive treatment of 10-20% reduction, which more accurately resolved astigmatic error in 90% of cases.
Conclusion
Femtosecond laser-assisted cataract surgery has the potential to greatly reduce astigmatism at the time of cataract surgery by creating laser arcuate incisions in the cornea. Laser astigmatic keratotomy yields predictable post-operative refractive results. Concerns for undercorrection can be resolved by making appropriate modifications to Donnenfeld’s nomogram for manual limbal relaxing incisions.