Larger Orthokeratology Treatment Zone Decentration Inhibits Myopic Progression

Larger treatment zone (TZ) decentration is associated with local defocusing changes which may inhibit the progression of myopia in children wearing orthokeratology (OK) lenses, according to research published in Ophthalmic and Physiological Optics.

Researchers enrolled 30 children (mean age 9.9±1.3 years, 13 boys) in the analysis and stratified them into 2 groups based on treatment zone (TZ) decentration: large TZ decentration (n=15, d_ave >0.7 mm) and small TZ (n=15, d_ave <0.7 mm). They fit each participant with 4-curve, reverse geometry OK lenses and instructed the children to wear the lenses for 8-9 hours per night. The team evaluated corneal changes during 1-, 3-, 6-, 9-, 12-, and 13-month follow-up visits. Baseline measurements for axial length (AL), spherical equivalent refraction (SER), and visual acuity (VA) were 24.89±0.89 mm, −2.63±0.77 D, and 0.09±0.07 logMAR, respectively. 

The investigators noted that axial length significantly increased to 25.16±0.88 mm at 1-year follow-up, revealing a change of 0.28±0.17 mm (t = −9.04; P <.01). They also observed a negative correlation between axial length elongation and  baseline age (β, −0.41; P =.01) and TZ decentration (β, −0.37; P =.03).

“Greater TZ decentration with the use of OK lenses was associated with slower axial growth and a more oblate retinal shape,” according to the researchers. “TZ decentration caused local defocusing changes, which may inhibit myopic progression. These findings may have important implications for improving optical designs for myopia control.”

Study limitations include the strict evaluation of retinal shape in the horizontal direction and a single center design. 

Reference

Li X, Huang Y, Zhang J, et al. Treatment zone decentration promotes retinal reshaping in Chinese myopic children wearing orthokeratology lenses. Ophthalmic Physiol Opt. Published online May 22, 2022. doi:10.1111/opo.12996