Orthokeratology Lens Decentration with Two Designs of Corneal Refractive Therapy™ Lenses: A One-Year Prospective Study

Background/Objectives: The objective of this study was to examine the trend of treatment zone (TZ) decentration over 12 months of orthokeratology (OK) wear using two Corneal Refractive Therapy (CRT) lens designs: standard (STD) and dual axis (DA). Methods: A prospective, randomized, longitudinal study was conducted at the Optometry Clinic of the Complutense University of Madrid. Subjects were randomly fitted with an STD design or DA design in one of the eyes. Refraction, uncorrected visual acuity (VA), and corneal topography were performed at baseline and after 1 night, 1 week, and 1, 3, 6, and 12 months of lens wear. Subjects requiring lens parameter adjustments or replacements after 3 months were excluded. Decentration was measured by subtracting pre-OK from post-OK tangential curvature maps at each visit, with decentration distance and corneal optical TZ being measured using MATLAB. Correlations between decentration and visual acuity (VA) were also analyzed. Results: A total of 30 healthy children (17 females and 13 males) with a mean age of 12.83 ± 2.42 years (range: 8–17 years) completed all the visits. No statistically significant differences (p > 0.05) were found between lens designs in horizontal, vertical, nor total decentration through the visits. However, for the STD design, horizontal and total decentration increased significantly at the last visit (p < 0.05). For the DA design, no significant differences were found over time (p > 0.05). No correlation was found between decentration and VA. Conclusions: Total decentration in both lens designs was similar throughout one year of follow-up. The standard design tended to decenter horizontally during the last 6 months, while the dual-axis design maintained consistent decentration throughout the year.