Accommodation response and spherical aberration during Orthokeratology

Abstract

Purpose: To evaluate the changes in the accommodative response and in the corneal and internal spherical aberration during three months of wear of orthokeratology lenses from the baseline. Methods: Fifty children aged 8 to 17 were recruited for a prospective study and were fitted with orthokeratology lenses. Refraction without cycloplegia, high and low uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), accommodation lag, horizontal near phoria without correction, corneal topography, corneal and total wavefront aberration were performed at baseline, 1 day, 1 week, 1 month and 3 months. Data were analysed by Student t-test for related samples, repeated measures ANOVA test and Pearson Correlation test. Results: The spherical equivalent (SE) before and after three months was -3.33 ± 1.60 D and -0.30±0.46 D, respectively. Accommodation lag was 0.53±0.38 D and 0.20±0.33 D at baseline and at three months, respectively. A moderate correlation between lag at the baseline and its change between baseline and the 3-month visit was found (P<0.05; R= 0.748). The spherical aberration (SA) increased for anterior corneal and total measurement, being statistically significant for all visits (P<0.05). The internal SA decreased: -0.105±0.006 at baseline and -0.196±0.203 at 1 week (P< 0.05). No difference between baseline and the follow up visits in posterior corneal SA was found (P>0.05) Conclusion: The negative SA of the lens increases during OK treatment compensated for the increase of the anterior corneal surface positive SA, in addition to increasing the accommodative response.