Epi-LASIK seen as advanced surface ablation procedure

October 1, 2005

Epi-LASIK combines the advantages of both LASEK and LASIK while minimizing the disadvantages of each

Results from one year of follow-up demonstrate that Epi-LASIK is a safe and effective alternative technique for photorefractive correction of low-to-moderate myopia and myopic astigmatism, said Vikentia J. Katsanevaki, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery.

She reported outcomes from a study of 196 eyes with attempted corrections ranging from –1.75 to –7.75 D (mean –3.59 D). The technique involved mechanical separation of epithelial sheets measuring 9.5 to 10 mm in diameter using the Centurion SES Epikeratome (Norwood Abbey) and ablation with the Allegretto (WaveLight Laser Technologie AG) laser. Postoperatively, all patients received topical diclofenac q.i.d. for two days and dexamethasone/tobramycin q.i.d. until re-epithelialization.

Dr Katsanevakia is a refractive surgeon affiliated with Vardinoyannion Eye Institute of Crete, University of Crete, Greece. The procedures were performed at the institute in collaboration with Ioannis J. Pallikaris, MD, and Maria I. Kalyvianaki, MD.

While it took up to three months to achieve the best UCVA, refractive and vision outcomes have been stable as follow-up extends to one year, haze has not been a significant problem and contrast sensitivity testing showed that by three months, patients on average demonstrated slight improvements at all spatial frequencies.

"We believe these results support the idea that Epi-LASIK combines the advantages of both LASEK and LASIK while minimizing the disadvantages of each," Katsanevaki said. "Epi-LASIK offers the benefits of a surface ablation procedure that is uncomplicated by pain, haze formation or alcohol cytotoxicity. It also has a more favourable wound healing profile, similar to LASIK but without that procedure's risk of flap complications and problems with dry eye."

In the study, patients were asked to rate pain every two hours for the first 10 hours after surgery and then at 24 hours using a 5-point scale on which 0 = no pain or discomfort, 1 = discomfort, 2 = burning feeling, 3 = pain not requiring medication, and 4 = pain requiring oral medication. The highest mean pain score was recorded at two hours after surgery (1.46) and it declined steadily thereafter, falling to 0.38 at 10 hours and 0.18 at 24 hours.

"Even at the peak at two hours after surgery, the mean pain score remained below the threshold of a burning feeling and only 12% of patients rated their pain as greater than discomfort," Katsanevaki said.

Data on visual acuity and refractive outcomes were available from 160 eyes seen at one month, 127 eyes seen at three months, 89 eyes at six months and 48 eyes from one year. Mean spherical equivalent at one month was –0.31 D, improved slightly to –0.20 D at three months and remained stable thereafter.

The predictability results showed that achieved correction at one month was ±1 D in about 92% of eyes.

Preoperatively, UCVA was 20/40 or better in 81% of eyes and 20/25 or better in 20%. UCVA of 20/40 or better was reached by 96% of eyes at one month while 70% of eyes at that visit had UCVA of 20/25 or better. By three months, UCVA was 20/25 or better in 91% of eyes and remained at that high level for the remainder of the available follow-up.

The best-corrected visual acuity (BCVA) results showed the only loss of two or more lines was recorded at one month after surgery when it occurred in 4% of eyes. At that visit, 23% of eyes had lost one line from preoperative BCVA, but about the same percentage had gained one or more lines.

By three months, only 9% of eyes had a one-line loss of BCVA while 41% had gained one or more lines. At later visits, 3% of eyes had lost BCVA and improvements were seen in more than half.