JUN 07, 2013
This prospective study reports initial results of intrastromal arcuate keratotomy performed with a femtosecond laser to treat preoperative minor to moderate corneal astigmatism. The results indicate that the femtosecond laser allowed the effective creation of precise, purely intrastromal, arcuate incision patterns with an excellent safety profile, rapid recovery, and stable vision without the known risks associated with incisions that penetrate Bowman membrane. A mean reduction of 76.6 percent in refractive astigmatism was achieved.
The authors believe this to be the first report of the feasibility, efficacy, and safety of intrastromal arcuate keratotomy in human eyes to reduce corneal astigmatism.
Sixteen patients with corneal astigmatism naturally occurring or after cataract surgery seen at a university eye clinic in Austria were treated with the Intralaser iFS (150 kHz) laser, which was used to perform paired arcuate cuts on the steep corneal axis completely placed within the corneal stroma. With 13 of the patients showing signs of nuclear sclerosis and expecting to undergo cataract surgery within six months, the authors sought to eliminate the need for a toric IOL or limbal relaxing incision.
No perforations occurred, and all incisions were placed at the planned locations. After a six-month follow-up, both mean refractive cylinder and mean topographic astigmatism were significantly reduced. There was excellent refractive and topographic stability over time. The endothelial cell density was unchanged, and patient satisfaction was very high.
The authors note that because this procedure was being used clinically for the first time and did not involve an incision through Bowman membrane, as has been the previous standard from which nomograms have been developed, there was no nomogram available. The particular incision pattern was designed to maximize the effect of the incision using a 90-degree arc length and a 30-degree cut angle in hopes of obtaining a stable final effect by creating a large healing area while minimizing glare with a comparatively large optic zone diameter. They believe that the astigmatic effect can be increased as the nomogram is further refined.