Excimer Laser Ablation Rate and Corneal Hydration

摘要: During excimer laser photorefractive keratectomy, dehydration of the cornea begins as soon epithelium is removed. Corneal hydration might affect ablation rate, which could accuracy correction. We studied effect corneal on rate in bovine eyes. To control hydration, corneoscleral rims were equilibrated dextran solutions varying concentrations. One button trephined from each rim underwent ablation. Hydrated tissue rates (amount collagen, ground substance, and water removed per pulse) dry component collagen substance calculated mass The hydrated at physiologic was 0.40 μm/pulse. As increased, increased by 5.6 μg/cm 2 /pulse increase unit (simple linear regression analysis, P=.0001). decreased linearly 0.82 Both clinical data theoretical arguments imply that determines refractive outcome after keratectomy. Since increases dries, significant before lead to relative overcorrections myopia. Surgeons should use a technique minimizes changes maximize predictability