By Fred Gebhart
SAN FRANCISCO -- October 27, 2009 -- New data presented here at the 2009 Joint Meeting of the American Academy of Ophthalmology and Pan-American Association of Ophthalmology (AAO-PAAO) suggests that advanced surface ablation (ASA) is a safe and effective method to treat residual myopia or hyperopia in eyes that have been treated with laser-assisted in situ keratomileusis (LASIK).
"This is the largest series to date," said Peter Rapoza, MD, Ophthalmic Consultants of Boston, Boston, Massachusetts, on October 25 during a poster presentation. "Bottom line is that you can do ASA on patients with prior LASIK. It is important to know that you can go back after cataracts and fine tune your patients' vision."
He said the findings should help quell the controversy that has surrounded surgical re-treatments following LASIK.
Nearly all of the potential re-treatments carry significant risks. Flap lifts can produce striae, epithelial ingrowth, and exposure of significant but unrecognised complications such as buttonholed or irregular flaps, especially if performed long after the primary surgery. Recutting flaps can produce bisected tissue planes with tissue mismatch and poor visual results.
Incisional surgery lacks the accuracy of excimer laser ablation, Dr. Rapoza continued. And photorefractive keratectomy (PRK) has been associated with inducing haze in a flap and significant interface inflammation. He added that there has only been a single report of PRK plus mitomycin C as a safe and effective option.
Researchers performed a retrospective review of 43 eyes (43 myopic and 8 hyperopic) that had undergone prior flap creation with a microkeratome or a femtosecond laser and excimer laser refractive ablation and were left with residual myopia, hyperopia, or mixed astigmatism. The average interval between primary LASIK and ASA retreatment was 81.9 months.
ASA was performed using 20% ethanol in an 8.0 mm (myopic) or 9.0 mm (hyperopic) well for 30 seconds, aspiration of alcohol and copious irrigation of the eye. Epithelium was removed with surgical sponges with the help of a crescent blade as needed. An excimer laser with wave front guided ablation and iris registration was used to impart the refractive treatment.
Following excimer laser treatment, mitomycin C 0.02% was applied to the bed on a surgical sponge for 15 seconds and the bed was then irrigated copiously. Bandage contact lenses were applied and remained in place until the epithelium was intact.
Postoperative medications included topical fluoroquinolone antibiotic and prednisolone acetate 1% daily for 1 week and a nonsteroidal anti-inflammatory as needed for 3 days. Loperamide 0.5% was given in a tapering regimen for 4 weeks.
Among the myopic eyes, a preoperative mean spherical equivalent of -0.75 D improved to 0.13 at 3 months with a slight regression to -0.07 at 6 months. One eye lost one line of best spectacle-corrected visual acuity and 1 eye had a regression of -1.75 D without any apparent nuclear sclerosis or keratoectasia. Mechanical epithelial debridement returned visual acuity to 20/25 and a -0.50 refraction.
Among the hyperopic eyes, the preoperative mean spherical equivalent of 1.53 D improved to -0.45 at 3 months and -0.21 D at 6 months. There were no sight-threatening complications in either group.
"This gives us another tool to get vision back to what the patient wants and expects," Dr. Rapoza said.
[Presentation title: Advanced Surface Ablation for the Treatment of Residual Myopic or Hyperopic Refractive Error Following LASIK. Abstract PO237]
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