Abstract
Purpose :
Orthokeratology (OK) affects corneal refraction through the overnight wear of RGP contact lenses. The full treatment effect is not established immediately, patients respond variably to these lenses, and ethnicity may have an influence on its outcomes. This preliminary study analyzed the correlation between baseline myopia, corneal refractive changes, and regression rates with short-term OK lens wear in Asian and non-Asian eyes.
Methods :
15 volunteers (8 Asian, 7 non-Asian) with healthy eyes and refractions of -1.00 D to -5.00 D and astigmatism up to -1.50 D were fitted with GOV OK lenses. Corneal refractive data in the center and the pupillary area were assessed with a Pentacam tomographer. The OK lenses were worn for one night, upon which the participants returned for evaluation. In addition, diurnal refractive regressions over 7 hours following lens removal were monitored. Statistical analysis included linear regression analysis and RM-ANOVA.
Results :
There was a strong association between baseline myopia and refractive change in the corneal center (P=0.006) and the pupillary area (P=0.0005). Differences between the changes in these areas were highly significant (P=0.0004) with a mean difference of -0.50 D (SD 0.10 D). Linear regression analysis resulted in moderate coefficients of determination for changes in the center and the pupillary area (R2 = 0.53 and 0.32, respectively). Ethnicity did not significantly influence either outcome (P = 0.1172 and P = 0.1240, respectively). The average diurnal refractive regressions in the center and the pupillary area occurred quickly in the first hour after lens removal (0.49 D and 0.40 D, respectively), and slower for the next four hours (0.16 D/hr and 0.13 D/hr, respectively). Five hours after each lens was removed, refractions leveled off at average values of -1.20 D and -0.90 D, respectively.
Conclusions :
In overnight orthokeratology, the baseline myopia had a significant impact on short-term refractive changes, whereas ethnicity did not. Refractive changes in the corneal center and the pupil area differed significantly and reduced quickly during the day in the first hour after lens removal and slower for the following four hours. They then leveled off but did not fully return to baseline. These findings are relevant for setting clinical expectations for overnight orthokeratology lenses and for communicating short-term expectations to patients.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.