RESUMEN
Purpose. To evaluate effectiveness of simultaneous topography-guided photorefractive keratectomy and corneal collagen cross-linking in mild and moderate keratoconus. Methods. Prospective nonrandomized interventional study including 20 eyes of 14 patients with grade 1-2 keratoconus that underwent topography-guided PRK using a Custom Ablation Transition Zone (CATz) profile with 0.02% MMC application immediately followed by standard 3 mw/cm(2) UVA collagen cross-linking. Maximum ablation depth did not exceed 58 µm. Follow-up period: 12 months. Results. Progressive statistically significant improvement of UCVA from 0.83 ± 0.37 logMAR preoperative, reaching 0.25 ± 0.26 logMAR at 12 months (P < 0.001). Preoperative BCVA (0.27 ± 0.31 logMAR) showed a progressive improvement reaching 0.08 ± 0.12 logMAR at 12 months (P = 0.02). Mean Kmax reduced from 48.9 ± 2.8 to 45.4 ± 3.1 D at 12 months (P < 0.001), mean Kmin reduced from 45.9 ± 2.8 D to 44.1 ± 3.2 D at 12 months (P < 0.003), mean keratometric asymmetry reduced from 3.01 ± 2.03 D to 1.25 ± 1.2 D at 12 months (P < 0.001). The safety index was 1.39 at 12 months and efficacy index 0.97 at 12 months. Conclusion. Combined topography-guided PRK and corneal collagen cross-linking are a safe and effective option in the management of mild and moderate keratoconus. Precis. To our knowledge, this is the first published study on the use of the CATz ablation system on the Nidek Quest excimer laser platform combined with conventional cross-linking in the management of mild keratoconus.
RESUMEN
PURPOSE: To study the value and safety of staining the anterior lens capsule in albino rabbits. SETTING: Ophthalmology Department, Cairo University, and Ophthalmic Pathology Department, Research Institute of Ophthalmology, Cairo, Egypt. METHODS: The experiment was divided into 3 stages. First, the capacity of different concentrations of crystal violet solution to stain the anterior lens capsule of postmortem albino rabbit eyes was tested. The toxicity of different concentrations of the dye (2% to 0.25%) was then tested to determine the highest concentration that was nontoxic to the cornea and trabecular meshwork. The third step was to detect possible toxicity of lower concentrations (0.1% to 0.05%). Different dye concentrations were injected into the anterior chamber of the rabbit eyes. The eyes were examined after 1 and 3 days, 1 week, and 1 month using light microscopy and scanning and transmission electron microscopy. RESULTS: Different concentrations of crystal violet stained the anterior lens capsule, allowing for easy capsulorhexis. The use of the 2% and 1% concentrations was accompanied with irreversible damage to all corneal layers. The use of the 0.5% concentration caused damage to stromal keratocytes and endothelium. The use of the 0.25% concentration did not damage any corneal layer or the trabecular meshwork. Lower concentrations of 0.1% and 0.05% also stained the capsule, providing good visibility for successful capsulorhexis, and were less toxic to the corneal endothelium. CONCLUSION: Staining the anterior lens capsule with 0.25% to 0.05% concentrations of crystal violet solution caused no injury to the cornea or trabecular meshwork in albino rabbit eyes.