Epi-LASIK shows decrease in aberrations at 3 months

Interim results in a multicenter study of epi-LASIK show less pain than PRK but slower visual recovery than LASIK.

Issue: January 1, 2006

ByBob Kronemyer

Early results in a multicenter trial of an epi-LASIK device show either no change or improvement in all higher-order aberrations, according to one investigator in the trial.

At the American Academy of Ophthalmology meeting in Chicago, Marguerite B. McDonald, MD, FACS, presented interim results of a clinical trial assessing the performance of the Norwood EyeCare Epikeratome system in the surgical correction of myopia.

Marguerite B. McDonald

“Early results indicate that [epi-LASIK] is safe and effective, with the impressive wavefront outcomes we expect of surface ablation,” Dr. McDonald said. “There is less pain than with PRK. The return of vision is a little slower than with LASIK, but the patients are functional.”

In epi-LASIK, an epithelial sheet is lifted mechanically with a microkeratome-like device, in this case the Norwood Epikeratome. No alcohol is necessary, and the epithelial sheet can be repositioned after laser ablation.

The procedure is designed to offer the advantages of both PRK and LASIK without the disadvantages of either technique, Dr. McDonald said.

Interim results

The multicenter trial included 130 patients with no previous ocular surgery. The average age was 38 years.

Average spherical equivalent of eyes was –4.37 D, ranging up to –8 D, with 2.5 D of astigmatism or less, Dr. McDonald said.

All laser treatments in the trial were wavefront-guided, performed on either the Alcon LADARVision laser or the Visx Star S4.

At 1-week postop, 25% of patients achieved uncorrected 20/20 visual acuity, she said.

“But 41% of the patients with this iteration of surface ablation were legal to drive the first day without glasses,” she said, referring to those with 20/40 or better visual acuity.

“This goes up slightly to 44% on day 4, but then jumps up dramatically, such that 79% are driving without glasses on postop day 7,” she said. “Yes, there is definitely a delay in return of vision compared to LASIK, but the patients are quite functional for those first few days,” Dr. McDonald said.

Best corrected visual acuity was also “beautifully maintained” in 88 patients with 3-month follow-up, she said.

At 1 month postop, spherical equivalent refraction in 65% of eyes was within ±0.25 D of emmetropia, according to Dr. McDonald. Another 5% were within ±0.625 D, and the remaining 30% were within ±0.75 D. By 3 months postop, 80% were within ±0.25 D, 3% were within ±0.625 D and 17% were within ±0.75 D.

In 91 eyes measured at 3 months postop, total root mean square error showed a “large decrease” from preop levels, from 5.17 µm to 1 µm, Dr. McDonald said.

There was also a decrease in lower-order aberrations (cylinder and sphere) and improvement or no change in all higher-order aberrations, “just as you would expect from surface ablation,” she said.

Status of devices for epi-LASIK

Manufacturer/Distributor	Product	Regulatory Status
Advanced Medical Optics	Epikeratome blade for the Amadeus II microkeratome	510(k) approved
Gebauer Surgical/ CooperVision	EpiVision	510(k) approved
Moria	Epi-K system	510(k) approved
Norwood EyeCare	Epikeratome	510(k) approved
Refractive Technologies	Horizon Epikeratome system	510(k) approved

Source: McDonald MB

Minimal problems

Postop discomfort levels were low, Dr. McDonald said.

“These clinical trial patients had a minimal pain control regimen,” she said, “ but even so, on a scale of 0 to 10, on the first day postop 3.7 was the average score.”

The score for day 3 was similar, but by day 5 had decreased to a score of 2.

“Discomfort rapidly resolved thereafter to 0,” she said.

One of the strengths of epi-LASIK is the claim that it induces less haze, Dr. McDonald noted, and the study indicated that this is the case. For either subepithelial or epithelial haze, the average score on a scale of 0 to 4 was “far below 1 at all postoperative time periods,” she said.

One eye in the trial developed a central corneal ulcer that was culture-positive for Staphylococcus aureus. There was no loss of best corrected visual acuity in that eye. Another eye experienced a paracentral stromal incursion.

“At 2 weeks out, this eye had a decrease of one line of best corrected vision,” Dr. McDonald said. “The surgeons scraped the eye, and then 2 weeks later the eye was treated with a laser scrape procedure. So there were three surgeries in 1 month.” Five months after the first surgery, this patient is still down one line of BCVA, she said.

For Your Information:

Marguerite B. McDonald, MD, FACS, can be reached at: margueritemcdmd@aol.com. Dr. McDonald is a paid consultant to Norwood EyeCare.

Norwood EyeCare, maker of the Epikeratome system for epi-LASIK, can be reached at 6455 E. Johns Crossing, Suite 425, Duluth, GA 30097; 1-866-EPI-LASIK; Web site: http://www.norwoodeyecare.com.