Surface procedures best for high myopes with thin corneas
Early results with epi-LASIK and femtosecond LASIK for high myopes showed better visual results than PRK or microkeratomes.
Both epi-LASIK and femtosecond LASIK procedures are safer and provide better visual acuity than mechanical microkeratomes in patients with high myopia and thin corneas, according to one Taiwanese ophthalmologist.
David C. Chang, MD, MPH, presented early clinical results with the two procedures at the ISRS/AAO annual regional meeting in Beijing.
The presentation comes at a time when refractive surgeons are once again appreciating the benefits of surface procedures such as sub-Bowman’s keratoplasty, according to Dr. Chang.
“Surface ablation compared to lamellar ablations can do higher corrections on thin corneas,” he said.
In addition, he said surface procedures are effective in cases with irregular topography, and they allow ophthalmologists to avoid flap complications.
Epi-LASIK with and without flaps
The study included 86 eyes of 45 patients who underwent either epi-LASIK or PRK for myopia with astigmatism.
The epi-LASIK group included 56 eyes operated on with or without flap removal. The mean age of the patients was 27 years, manifest refractive spherical equivalent (MRSE) was –8.28 D, cylinder was –0.63 D and corneal thickness was less than 500 µm, according to Dr. Chang.
The PRK group included 30 eyes. The mean age of the patients was 29 years, the MRSE was –7.59 D, cylinder was –0.75 D and the corneal thickness was also less than 500 µm.
Dr. Chang said he evaluated epithelial defect size, symptoms, uncorrected visual acuity and best corrected visual acuity at 3 months postoperatively.
Data comparing the epithelial defect size between epi-LASIK with and without flap removal and PRK showed that, at 5-days postop, the epithelium in eyes with flap removal healed quicker than the PRK eyes or the eyes without flap removal.
“Epi-LASIK with the procedure of mechanical separation without alcohol preserves better integrity of the epithelium and stroma,” Dr. Chang said.
Similarly, subjective pain results showed that by day 7 postop, the eyes with the flap removed were free of pain while the other two groups reported some pain. The PRK group had a significantly higher level of pain than both groups of epi-LASIK eyes, according to Dr. Chang.
Visual results showed that the flap removal group had better UCVA and BCVA than the other two groups at 3 and 7 days and at 1-month postop.
“The value of the epithelial flap might not be so clinically important compared with PRK or LASEK procedures,” Dr. Chang said. “However, long-term studies to evaluate the efficacy of epi-LASIK looking at corneal haze, corneal sensitivity and tear function and, of course, quality of vision and higher-order aberrations are also worth investigation.”
For more information:
David Chaokai Chang, MD, MPH, can be reached at Taiwan Nobel Eye Institute , 4 F , NO 179 , Section 2 , DunHua South Road , Taipei 10690 , Taiwan; +886-2-23705666; fax: +886-2-87730403 ; e-mail: chaokai@nobelgroup.com.tw.