Effect of the Spheric Multi-curve Lens on Changes of Corneal Topography and Endothelial Cell in Keratoconus

PURPOSE: To analyze the effect of the spheric multi-curve lens on the changes of corneal topography and endothelial cells in keratoconic eye. METHODS: Forty-nine eyes of 37 keratoconic patients who had been followed more than 6 months were included in the study. Twenty-six eyes of 19 patients were fitted with spheric multi-curve lens, and the remaining 23 eyes of 18 patients were followed without any lens fitting as control. After spheric multi-curve lens fitting, visual acuity, and slit lamp examination were evaluated. Changes of corneal topography and endothelial cell were evaluated at first visit and 6 months after lens fitting. RESULTS: After lens fitting, 21 eyes (80.8%) showed best corrected visual acuity of better than 20/25. The value of the steepest Sim-K, shape factor (SF), and apical corneal power on corneal topography were significantly decreased in the spheric multi-curve lens fitting group compared to the control group (p0.05). There were no significant differences in change of corneal endothelial cell density, mean cell area and percentage of hexagonal cell between the two groups (p>0.05). CONCLUSIONS: Short-term wearing of spheric multi-curve lens for 6 months in keratoconic patients showed no effect on progression of keratoconus and cornealendothelial cells.

Effect of Reverse Geometry Lens on Correction of Moderate-degree Myopia and Cornea

PURPOSE: To evaluate the effect of reverse geometry lens (RGL) on correction of moderate degree myopia and cornea in patients of moderate-degree myopia. METHODS: 48 eyes of 82 eyes were chosen to wear reverse geometry lens and the remaining 34 eyes were fitted with rigid gas permeable (RGP) lens. The subjects were tested three days, one, two weeks, one, two and three months after fitting the lens. Uncorrected visual acuity, manifested refractive error, corneal thickness and corneal endothelial cell count were evaluated. corneal topography were performed. RESULTS: The uncorrected visual acuity was increased at 0.05 LogMAR after two weeks. and manifested refractive error decreased during the first months, thereafter stabilizing to -0.2 D (diopters). Corneal thickness was 540.4 micrometer and 583.0 micrometer in the center and mid-periphery, decreased to 505.2 micrometer and 572.7 micrometer, respectively, three months after RGL fitting (p<0.05). Endothelial cell count was 2663.5 cells/mm2 and 2541.5 cells/mm2 in the center and mid-periphery, 3 months after RGL fitting and endothelial cell count was not significantly different compared with that of pre-fitting. There was no statistical difference between RGL fitting group and RGP fitting group in the change of corneal endothelial cell count. CONCLUSIONS: RGL was found to be effective in correction of moderate-degree myopia. It had minimal effect on corneal endothelium, in short-term usage, however, the change of corneal thickness suggests that RGL fitting may effect on corneal epithelium and stroma.

Clinical Results of LASIK Enhancement

PURPOSE: To assess the results of laser in situ keratomileusis (LASIK) enhancement by lifting the original flap and reablation for the treatment of myopic regression and undercorrection after initial LASIK. METHODS: We analyzed LASIK enhancement results in 19 patients (27 of 1026 eyes) which had myopic regression or undercorrection after initial LASIK. We evaluated the changes of refractive error, uncorrected visual acuity, best corrected visual acuity, corneal topography, and corneal thickness before and six months after enhancement. We also analyzed enhancement rate according to the original refractive error. RESULTS: Overall, the mean spherical equivalent (SE) was -7.10+/-1.78 diopters (D) before LASIK, -2.80+/-0.79D prior to enhancement and -0.31+/-0.46D at 6 months after enhancement (p<0.001). The uncorrected visual acuity at 6 months after enhancement was 1.0 or better in 10 eyes (37.0%) and 0.5 or better in 27 eyes (100%). Best corrected visual acuity (BCVA) did not change in 12 eyes (44.4%) and improved 1 line or more in 9 eyes (33.3%) at 6 months after enhancement. The final refractive error of one group which underwent enhancement within postoperative 3 month was closer to emmetropia than that of the other which had enhancement after postoperative 3 month, but there was no statistically significant difference (p=0.589). CONCLUSIONS: LASIK enhancement by using the original flap was an effective procedure, if the changes of refractive error were stable on refraction or corneal topography.