Abstract
Purpose :
Few studies have investigated the effect of orthokeratology lenses (OKL) over a period of more than 2 years. The purpose of this study was to investigate if the efficacy of OKL decreases in Danish children during 3 years of usage measured by change in axial length (AL).
Methods :
The CONTROL study was a 1:1 randomized controlled trial investigating the efficacy of OKL in Danish children aged 6-12 years during an 18-month follow-up. The intervention group used OKL, and the control group wore single-vision-spectacles. In the CONTROL2 study the same children were followed for additional 18 months with the control group crossed-over to OKL, and the OKL group continuing OKL. This sub-study presents the 3-year data from the original OKL group. The OKL used for this study was DreamLite® (CooperVision, San Ramon, California, USA). AL and central corneal thickness (CCT) on both eyes were measured with Lenstar LS900 (Haag-Streit, Koeniz, Switzerland) at 0, 6, 12, 18, 24, 30, and 36 months. Five to six measurements on both eyes were obtained at each follow-up visit. The change in AL was adjusted for the decrease in CCT caused by the OKL treatment. A nested mixed model was used to allow inclusion of data from both eyes and to include data from subjects who dropped out until dropout occurred. Stata/BE software (version 18.0; StataCorp, College Station, TX, USA) was used.
Results :
The OKL group comprised 30 children (female 53%, age 9.77 years ± 1.38, cycloplegic spherical equivalent refractive error -2.25/-2.24 D ± 1.12/1.16, AL 24.12/24.11 mm ± 0.72/0.69 for right and left eye, respectively. During the 36-month follow-up 16 children dropped out leaving 14 children completing the study.
There was no statistically significant decline in treatment efficacy during the 3-year follow-up. The mean increase in AL from baseline to 6-month follow-up was 0.066 mm. Hereafter, the increase was 0.059 mm (mixed model, p = 0.89, 95% CI –0.11 to 0.09), 0.083 mm (p = 0.83, 95% CI –0.14 to 0.17), 0.082 mm (p = 0.88, 95% CI –0.19 to 0.23), 0.097 mm (p = 0.82, 95% CI –0.24 to 0.30), and 0.096 mm (p = 0.85, 95% CI –0.29 to 0.35) for 6 to 12, 12 to 18, 18 to 24, 24 to 30, and 30 to 36 months follow-up, respectively. However, there was an increasing trend.
Conclusions :
The efficacy of OKL did not decrease significantly during 3 years of usage. However, the change in AL had an increasing trend.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.