Interim study results favor femtosecond laser astigmatic keratotomy procedure

Dr. StodulkaCzech Republic-Preliminary results from a single center phase IV study support the safety and efficacy of femtosecond laser astigmatic keratotomy in patients undergoing cataract surgery or refractive lens exchange, said Pavel Stodulka, MD, PhD.

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The study plans to treat 50 eyes and follow them for 1 year, according to Dr. Stodulka, the operating surgeon in the single center study that is evaluating laser astigmatic keratotomy using the Victus Femtosecond Laser Platform (Technolas, Bausch + Lomb).

So far, 19 eyes with an average preoperative manifest cylinder had completed follow-up. At 1 year, manifest cylinder averaged 0.17 D and was ≤0.5 D in 95% of eyes, said Dr. Stodulka, chief executive officer, Gemini Eye Clinic, Czech Republic.

Eye after the femtosecond laser capsultomy, fragmentation and arcuate incisions before the manual intraocular part of surgery (Images courtesy of Pavel Stodulka, MD, PhD).

He reported that the astigmatic correction was stable during follow-up and distance best corrected visual acuity was unchanged or improved compared with the preoperative level in all eyes. Among 27 eyes seen at 6 months, 75% had ≤0.5 D of residual cylinder.

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“The 12-month results are superior to the 6-month outcomes, perhaps because fewer eyes have reached the 12-month visit. However, the percentage of eyes with less than 0.5 D of residual cylinder at 6 months still compares favorably to published data for correction of astigmatism using toric IOLs and is better than published outcomes for manual astigmatic keratotomy,” Dr. Stodulka said. “Now, we are continuing patient enrollment and follow-up.”

Opened laser arcuate keratotomy shows regular shape of incision.

The study is including patients who are >40 years old with 1 D to 3 D of regular corneal astigmatism and stable keratometry <47 D. In addition, they must have undergone uncomplicated cataract or RLE surgery and have no intraocular pathology other than cataract or any history of previous ocular surgery.

The astigmatic cuts are made at an 8.5 mm optical zone at 80% depth and using the Hoffman modification of the Oshika nomogram.

“In this study, the astigmatic cuts are being made through the epithelium and Bowman’s membrane,” Dr. Stodulka said. “However, the femtosecond laser can also be used to create intrastromal incisions, which could offer an advantage for increased patient comfort.”

In all cases, the femtosecond laser was also used for capsulotomy and lens fragmentation, and phacoemulsification was performed through a 1.8 mm incision using the Stellaris PC platform (Bausch + Lomb). The astigmatic incisions were opened with a spatula at the end of the surgery.

“The theoretical advantage of using the femtosecond laser to create arcuate incisions relates to its precision,” Dr. Stodulka explained. “Relative to a manual technique, the laser cuts are more accurate in terms of position, shape, length, and depth.

OCT showing a non-perpendicular direction of laser arcuate incision to 80% corneal depth

“Anterior segment OCT confirms the precise positioning of the laser arcuate incisions and my impressions are that the incisions open very easily and are very regular in their depth and shape,” he added. “Based on those features, we believe that laser astigmatic keratotomy will provide more consistent results than manual arcuate keratotomy.”

The safety review showed that the laser arcuate cuts intersected with the manual main incision performed at the same steep axis in one eye.

There were no cases of perforation and no eyes showed evidence of epithelial ingrowth.

Dr. Stodulka is a consultant to Bausch + Lomb.