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Tear cytokines and growth factors are likely to modulate the wound healing process following corneal epithelial injury. Hepatocyte growth factor (HGF) is a paracrine mediator of epithelial proliferation, motility, and differentiation that is produced by keratocytes and the lacrimal gland. Tear samples were collected preoperatively and one, two, and seven days postoperatively in eyes undergoing excimer laser surface ablation [photorefractive keratoplasty (PRK) or phototherapeutic keratoplasty (PTK)]. Tear HGF concentration was measured with a sensitive ELISA assay, Tear HGF production was calculated using the tear flow rate in the collection capillary and HGF concentration. Although the instantaneous concentration of HGF in tears decreased significantly in the days following PRK, a large increase in tear flow resulted in a marked increase in HGF bioavailability. The heparin-binding characteristics of HGF would result in increased binding to glycosaminoglycans and other heparin-like matrix components and, therefore, increased growth factor availability to the cognate receptor. This is the first report documenting changes in tear film HGF production. HGF may have an important function in maintenance and wound healing of the ocular surface epithelium since HGF is present in the normal tear film and the HGF secretion rate increases markedly in parallel with aqueous tear production following corneal surgical injury.

Purpose: To summarize the initial results of excimer laser photorefractive keratectomy (PRK) in 114 eyes of 89 patients using the Coherent-Schwind system and assess its safety, efficacy, and predictability. Setting: Hospital San Jose de Monterrey-ITESM, Mexico. Methods: The Coherent-Schwind Keratom excimer laser was used to correct low myopia (manifest spherical equivalent from −1.00 to −6.00 diopters [D], with manifest cylinder of −1.00 D or less) or myopic astigmatism (manifest spherical equivalent from −2.75 to −6.75 D, with manifest cylinder from −1.00 to −4.50 D) with standard settings. Ablation zone diameters were from 5.9 to 6.3 mm (low myopia) and 5.9 to 8.2 mm (astigmatism) with a repetition rate of 12 Hz. Follow-up was from 1 month (low myopia, n = 71; astigmatism, n = 35) to 6 months (low myopia, n = 36; astigmatism, n = 17). Results: Six months after PRK, uncorrected visual acuity was 20/40 or better in 94% of the low myopia eyes (n = 36) and 77% of the astigmatism eyes (n = 17). Intended correction was within 1.00 D of the target spherical equivalent in 81 and 88% of eyes, respectively. No eyes in the low myopia group lost two lines of best corrected visual acuity, although 12% in the astigmatism group did. Conclusion: The Coherent-Schwind excimer laser appears to be effective in the treatment of low myopia and astigmatism, with results comparable to those of other laser systems after 6 months of follow-up. Further study of best corrected visual acuity loss after treatment of compound myopic astigmatism with this laser is warranted.

Purpose: To compare 18% ethanol versus mechanical epithelial debridement in a group of patients having photorefractive keratectomy (PRK) for low to moderate myopia or astigmatism. Setting: Hospital San Jose de Monterrey, Mexico. Methods: This prospective, paired study comprised 18 patients who had bilateral PRK between June 1994 and March 1995. One eye had ethanol (alcohol) debridement and the other, mechanical. Time between PRKs was about 6 months. The two groups (alcohol versus mechanical) were compared for rate of re-epithelialization, refractive outcome, improvement in uncorrected visual acuity (UCVA), subjective haze grading, and loss of best corrected visual acuity (BCVA). Results: There was a nonsignificant trend in the alcohol-treated eyes toward a more rapid visual recovery. One week after PRK, 76% in the alcohol group but only 31 in the mechanical group had a UCVA of 20/40 or better. There were no significant between-group differences in rate of re-epithelialization, refractive outcome, subjective haze grading, and loss of BCVA. Conclusion: Chemical de-epithelialization with dilute ethanol appears to be a simple, safe, and effective alternative to mechanical scraping before PRK and might promote faster visual rehabilitation.

PURPOSE The corneal epithelium is generally removed before photoablation in photorefractive keratectomy (PRK) because laser transepithelial PRK may result in surface irregularity caused by variability in epithelial thickness and differing ablation rates between epithelium and stroma. We compared the effects of mechanical deepithelialization with chemical epithelial removal by using 50% ethanol on the corneal structure. METHODS Fourteen rabbits underwent corneal deepithelialization by using a blade in the left eye and 24 h later in the right eye. Another 14 rabbits underwent corneal deepithelialization by using 50% ethanol solution. Half of the eyes treated with each technique underwent PRK after deepithelialization. Pachymetry was performed before and after each procedure on right eyes. Keratocyte and neutrophil densities were assessed by light microscopy. RESULTS Among non-laser-treatment groups, eyes that underwent mechanical deepithelialization had decreased corneal thickness (p = 0.001), increased keratocyte densities (p = 0.03), and no significant difference in neutrophil densities (p = 0.91) compared with chemically treated eyes 24 h after surgery. Among laser-treatment groups, eyes that underwent mechanical epithelial removal had increased keratocyte densities (p = 0.001), decreased corneal thickness (p = 0.03), and increased neutrophil densities (p = 0.03) 24 h after surgery compared with chemically treated eyes. CONCLUSION Deepithelialization with 50% ethanol causes more keratocyte loss with perhaps more corneal edema, but less stromal influx of neutrophils, than does a mechanical technique 24 h after PRK in a rabbit model. Corneal deepithelialization with dilute ethanol may be a viable option in PRK. However, further investigation into the safety of this technique is warranted before it can be widely applied clinically.

Purpose To report the occurrence and follow-up of ec-topic, interface, epithelial growth after laser in situ keratomileusis (LASIK) in four eyes (three patients) and provide suggestions for management. Methods Each eye was examined by slit-lamp biomicroscopy, and corneal topography was obtained with the Tomey TMS-1 instrument. Results Each eye with epithelium within the interface after LASIK developed interface opacities and surface irregularity. One eye had an early surgical intervention, and three eyes were observed. Each eye lost at least one line of best spectacle-corrected visual acuity and had visual disturbance at the last follow-up visit. Conclusions The presence of epithelium within the lamellar interface is a significant complication after LASIK. In some cases, interface epithelium may be associated with early postoperative inflammation. When reoperation is required to treat this complication, we suggest scraping of both sides of the interface with a metal blade. In some cases, light excimer laser treatment can be used to facilitate epithelial removal.