Comparison of laser and manual removal of corneal epithelium for photorefractive keratectomy.
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.


CONCLUSIONS
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.
Gimbel
H V
HV
Gimbel Eye Center, Calgary, Alberta, Canada.
DeBroff
B M
BM
Beldavs
R A
RA
van Westenbrugge
J A
JA
Ferensowicz
M
M
D000328:Adult; D016022:Case-Control Studies; D003315:Cornea / Q000187:drug effects / Q000502:physiology / Q000601:surgery*; D003907:Dexamethasone / Q000008:administration & dosage; D004848:Epithelium / Q000187:drug effects / Q000502:physiology / Q000601:surgery; D005260:Female; D005469:Fluorometholone / Q000008:administration & dosage; D006801:Humans; D053685:Laser Therapy; D008297:Male; D009883:Ophthalmic Solutions; D011182:Postoperative Care; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000188:drug therapy / Q000503:physiopathology; D054140:Refractive Surgical Procedures; D012189:Retrospective Studies; D014792:Visual Acuity
D009883:Ophthalmic Solutions; D003907:Dexamethasone; D005469:Fluorometholone