Endpoints met for topography-guided primary myopic LASIK

Chicago-In an interim analysis of 6-month data, primary LASIK using a proprietary topography-guided algorithm (T-CAT, Alcon Laboratories) met the clinical safety and performance endpoints of a phase III study investigating its use for correcting myopia with or without astigmatism in healthy eyes, said R. Doyle Stulting, MD, PhD.

The results from 249 eyes treated at 10 investigational sites in the United States were presented by Dr. Stulting, director of corneal disease and research, Woolfson Eye Institute, Atlanta. The treatment was planned using topography (Allegro Topolyzer, Alcon) and refraction data and was performed using the 400-Hz excimer laser (Allegretto Wave Eye-Q, Alcon).

Mean MRSE for the 249 eyes was –4.6 D preoperatively and they had a mean attempted cylinder correction of 1.9 D. At 6 months mean MRSE was 0.01 D and mean cylinder was also close to emmetropia.

Predictability analysis showed 93% of eyes were within 0.5 D of intended MRSE and 98.8% were within 1 D. About one-third of eyes had uncorrected visual acuity of 20/12.5 or better, results from a subjective questionnaire showed all categories of visual symptoms were improved from preoperatively, higher-order aberrations measured at 5 mm were slightly increased, and best-corrected visual acuity (BCVA) was significantly improved.

“Going into the study, my expectation was that there would be no advantage for the topography-guided procedure relative to the outcomes we are used to achieving using wavefront-optimized LASIK with this laser,” Dr. Stulting said. “Therefore, I was surprised to see the improvements in BCVA and in visual symptoms, and I am not sure how to explain these findings.”

However, despite the positive results, he commented that treatment of highly aberrated post-refractive surgery eyes may be the best application of the topography-guided procedure.

“One day, surgeons in the United States may have the choice of using topography-guided LASIK as a primary procedure,” he said. “However, they need to recognize there is a huge learning curve and this procedure requires a degree of physician intervention, knowledge, and participation that far exceeds what we do today.”

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