The effect of age on short-term orthokeratology

Purpose. The purpose of this study is to investigate the effect of age on the response to short-term (one hour) open eye orthokeratology (OK) lens wear. Methods. Sixty volunteer subjects were divided into three groups (n = 20 per group) comprising children (group 1, mean age: 9.5 +/- 1.7 years), young adults (group 11, mean age: 24.6 +/- 3.7 years), and older adults (group III, mean age: 43.9 +/- 6.1 years). Subjects wore reverse-geometry lenses (BE; UltraVision Pty. Ltd., Brisbane, Australia) under open-eye conditions for 1 hour in one eye only. Unaided logarithm of the minimum angle of resolution (logMAR) visual acuity, corneal astigmatism calculated from simulated keratometric (SimK) readings, corneal asphericity and apical radius of curvature (Medmont corneal topographer), and total corneal, stromal, and epithelial thickness (Holden-Payor optical pachometer) were measured before and after lens wear. Two-tailed paired Student t-test were used to examine changes after OK, and analysis of variance and Bonferroni post hoc t tests were used to compare between groups with a critical p value of 0.05. Results. All groups showed statistically significant (p < 0.05) improvement in unaided visual acuity, a trend for more positive (less prolate) corneal asphericity, increase in apical corneal radius, and decrease in central total corneal thickness after OK lens wear. Compared with groups I and II, group III showed significantly less change (p < 0.05) in visual acuity, apical corneal radius, corneal asphericity, central total corneal thickness, and epithelial thickness. Conclusions. Corneal and visual changes found in this study confirm previous reports of the rapid effects of short-term OK lens wear. Older lens wearers showed a reduced or delayed response to reverse-geometry lens wear in the short term, suggesting a reduced corneal epithelial response to interventions with increasing age.