EpiLASIK study yields positive interim results

February 1, 2006

Chicago—Early results from a multicenter, prospective study provide evidence to support the conclusion that EpiLASIK is a safe and effective procedure that may fulfill its promise to offer the advantages of PRK and LASIK with the disadvantages of neither, said Marguerite B. McDonald, MD, at Refractive Surgery 2005: Simply the Best.

Dr. McDonald presented interim findings from 130 eyes enrolled in a clinical trial evaluating EpiLASIK for myopia using the Centurion SES epikeratome (Norwood Abbey) to lift the epithelial sheet. The data so far show the procedure is associated with less pain and less haze than PRK, but maintains the impressive wavefront outcomes of surface ablation. Return of visual acuity is somewhat slower than after LASIK, but an appreciable proportion of patients have functional vision early after surgery.

"Longer follow-up is required, and we can also expect further refinement in technique, technology, and surgeon skills, but these results are encouraging," said Dr. McDonald, clinical professor of ophthalmology, Tulane University.

"Scanning electron micrographs confirm that this technique preserves the lamina lucida and lamina densa whereas use of alcohol to facilitate LASEK flap creation disrupts both of these basement membrane layers," Dr. McDonald said.

By avoiding death of epithelial cells at the time of flap creation, EpiLASIK avoids the subsequent activation of stromal keratocytes and their transformation into fibroblasts.

"With injury to the epithelial cells, there is a sudden release of proinflammatory cytokines that initiate the pathway for keratocyte transformation. The cells in the EpiLASIK epithelial sheet are fatally injured at the time of surgery, but most are still alive. By the time they die several days later and release their proinflammatory cytokines, the stroma is past its moment of vulnerability," Dr. McDonald said.

The study with the Centurion SES epikeratome enrolled eyes with no history of ocular surgery, with a preoperative SE ranging from –0.5 to –8.0 D, and up to –2.5 D of cylinder. All ablations were wavefront-guided. Slightly more than three-fourths were performed using the VISX system and the rest were performed using the Alcon system.

The study group was split almost evenly by gender. Mean age was 38 years, but the range was up to 67 years.

Follow-up evaluations

Patients were seen at postoperative day 1 and then daily until re-epithelialization occurred. Thereafter, patients were seen at approximately 1 and 3 months after surgery. Of the 130 eyes, about two-thirds had completed the 3-month postoperative visit.

The functional analyses showed that early after surgery, relatively few patients achieved UCVA of 20/20 or better. However, on postop days 1 and 4, 41% and 44% of patients, respectively, could see 20/40 or better without glasses, and by the end of the first week, that proportion jumped to 79%.

"These results show that nearly half of the patients who undergo this procedure can legally drive on the first day after surgery, and from a safety perspective, BCVA has been beautifully maintained throughout the study," Dr. McDonald said.

The refractive outcomes showed that at 1 month, SE was within 0.25 D of emmetropia in 65% of eyes. At 3 months, 80% were within 0.25 D of emmetropia.