Abstract
Abstract: :
Purpose: To investigate the effect of age on the response to short–term (one hour) open eye orthokeratology (OK) lens wear. Methods: Subjects were divided into two groups comprising young adults (group I, n=18, mean age 24.3 ± 3.9 years) and older adults (group II, n=18, mean age 43.9 ± 5.3 years). Subjects wore reverse geometry lenses (BE; UltraVision Pty Ltd, Brisbane, Australia) under open–eye conditions for one hour in one eye only. Changes in unaided visual acuity were measured using a logMAR chart, changes in corneal asphericity and apical radius were measured with the Medmont corneal topographer, and changes in central corneal, stromal and epithelial thickness were measured with the Holden–Payor optical pachometer. Two–tailed paired Student t–tests were employed to compare changes before and after orthokeratology and independent samples Student t–tests were used to compare between the two groups, with a critical p–value of 0.05. Results: After one hour of open eye wear, statistically significant changes from baseline (p<0.05) were found in both subject groups for unaided visual acuity, corneal asphericity, apical corneal radius and central corneal and epithelial thickness. No significant changes were found in central stromal thickness. Comparisons between groups revealed statistically significant differences (p<0.05) in the improvement in unaided visual acuity (group I: 0.61 ± 0.29, group II: 0.15 ± 0.12 logMAR units), flattening of apical corneal radius (group I: 0.15 ± 0.09, group II: 0.05 ± 0.06 mm), decrease in corneal asphericity (group I: 0.20 ± 0.13, group II: 0.09 ± 0.09) and decrease in central corneal thickness (group I: –5.7 ± 3.6, group II: –2.6 ± 5.7 µm) and epithelial thickness (group I: –9.8 ± 10.7, group II: –2.6 ± 3.7 µm). Conclusions: Corneal and visual changes found in this study confirm previous reports on the effects of short–term OK lens wear. Older lens wearers show a reduced or delayed response to reverse geometry lens wear.
Keywords: contact lens • cornea: clinical science • topography