Excimer photorefractive keratectomy for low myopia and astigmatism with the Coherent-Schwind Keratom.

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.

Effect of fibrin on morphologic characteristics of retinal pigment epithelial cells.

Human retinal pigment epithelial (RPE) cells in culture, when overlaid by a fibrin clot, lose their normal epithelial morphologic features and migrate into the overlying clot as fibrocytelike cells. The behavior of human RPE cells on exposure to fibrin correlates well with the observed response of RPE in several ocular disorders in which fibrin deposition within the eye is an important feature. The mechanism of recognition and interaction between fibrin and RPE cells is unknown. The in vitro system used in our current studies allows the investigation of this interaction in a controlled environment. Further study of the interaction between human RPE cells and fibrin offers the possibility of improving our understanding and treatment of several blinding ocular disorders, including the disciform phase of senile macular degeneration, proliferative vitreoretinopathy, and the sequelae of ocular trauma.