The effects of night wear orthokeratology lenses on central cornela thickness

Purpose: This study was performed to determine the effectiveness and safety of Night Move™ orthokeratology lenses and to examine their effects on central corneal thickness. Methods: Ten subjects (20 eyes) with myopia less than 5D and with the rule astigmatism less than 1.50D were fitted with the Night Move™ orthokeratology lenses. The lenses were worn at night for a period of 30 days. Subjects were examined prior to the study, at 1 day, 7 days and 30 days. Unaided visual acuity, refractive error, keratometric readings, intraocular pressure and central pachymetry measurements were determined at each visit. Results: All eyes reached unaided visual acuities of at least 20/40 with 90% reaching 20/20 or better. Mean refractive error demonstrated a decrease in myopia from -2.26D to -0.04D at 30 days. The mean steep K was reduced 1.46D at 30 days. The mean decrease in central corneal thickness was 0.022mm after 30 nights of lens wear. Mild cases of epithelial staining were seen in 2 eyes at 1 day and 7 days. No staining was seen after 7 days. All other ocular health was unremarkable throughout the study. Conclusions: Changes in mean keratometric readings and mean refractive error do not explain the acuities achieved by the subjects in the study. A decrease in central corneal thickness provides the additional power to allow subjects to achieve optimum visual acuity. The change in corneal thickness is small compared to photorefractive surgeries and provides a safer alternative maintaining greater corneal integrity