Comparison of Laser and Manual Removal of Corneal Epithelium for Photorefractive Keratectomy

Abstract

BACKGROUND: Photorefractive keratectomy relies on precise ablation of cornea stromal tissue to achieve a desired change in refraction. The routine technique for photorefractive keratectomy has been manual debridement of the epithelium prior to performing excimer laser ablation. We investigated whether laser ablation versus manual debridement of the corneal epithelium influences the refractive result. METHODS: A retrospective matched controlled study analyzing the refractive outcome of 46 eyes after excimer laser photorefractive keratectomy was performed. Half of the eyes had the corneal epithelium ablated with the excimer laser, while the other half had mechanical removal. Topical postoperative corticosteroid dosing was different in the two groups. All photorefractive keratectomies were performed by the same surgeon (H.V.G.). The two groups were analyzed for statistical differences in refractive outcomes and corneal haze after 6 months. RESULTS: The mean preoperative spherical equivalent refraction in the laser removal group was -5.11 diopters (D), and -5.09 D in the manual group. At 6 months postoperatively, the mean spherical equivalent refraction in the laser group was +0.03 D and -0.40 D for the manual group (p = .21). At no point postoperatively was there any significant difference in the mean refractive outcome or variance of the refractive results between the two groups, although there was a trend toward greater correction with laser ablation of epithelium. There was no statistical difference in the amount of stromal haze by slit-lamp microscopy in the two different debridement groups. There was no significant difference in final uncorrected visual acuity, rate of reepithelialization, or reported incidence of halos or glare between the two groups. CONCLUSION: There was a tendency toward greater refractive correction at 6 months using the laser for corneal epithelial removal than manual debridement, although the difference was not statistically significant. The trend toward slightly higher correction emphasizes the need for care when removing epithelium with the laser to prevent concomitant stromal ablation. [J Refract Surg. 1995;11:36-41.]

The Effectiveness of Corneal Epithelial Debridement Performed with an Alcohol-Impregnated Sponge

“…Mechanical debridement is effective and relatively straightforward but may prolong operative duration, especially in surgeons who are new to refractive surgery. Prolonged operation time can reduce stromal hydration due to evaporation, which may reduce the safety and efficacy of laser treatment [9]. Besides, it has been reported that mechanical debridement creates scratches and grooves on the Bowmanʼs membrane and the epithelium cannot be completely removed in some circumstances, leaving various amounts of the epithelium on the cornea, which may affect the depth of ablation with an excimer laser [10].…”

Single-Step Transepithelial Photorefractive Keratectomy in Low to Moderate Myopia: A One-Year Follow-Up Study

“…Transepithelial PRK has been used for refractive laser correction since it was introduced in the early 1990s, and became more popular after studies conducted by Aron-Rosa et al 7 and Gimbel et al 8 It is an effective and safe technique and is well tolerated by patients. 9 Published research [10][11][12] has compared clinical results between different methods of epithelial removal, including the transepithelial method using the Schwind Amaris laser platform or other two-step procedures.…”

New method for reshaping the cornea

“…Its destruction initiates an active healing response that can lead to a loss of correction (myopic regression) from the initial refractive correction. [28][29][30] Because of the loss of best-corrected visual acuity (BCSVA), corneal scarring, and the limited predictability seen with deep surface ablation using the PRK technique, interest in the LASIK procedure has increased substantially. 31,32…”