Comparison of myopia control efficacy and retinal defocus in adolescents with moderate to high myopia when wearing aspheric lenses with different back optic zone diameters.

Objectives: To compare aspheric lenses with different back surface optic zones, analyze the defocus distribution in adolescents with moderate to high myopia and the changes in the eye axis after wearing the lenses, and provide a basis for the precise clinical fitting of orthokeratology lenses.​.

Methods: A prospective randomized controlled study was conducted from 2021 to 2025. 346 adolescent myopia patients were selected at Beijing Ming Vision and Ophthalmology Clinic. They were divided into Group A (small optic zone, 5.0 mm) and Group B (conventional optic zone, 6.0 mm). This study systematically compared two types of orthokeratology lenses with different back surface optic zone designs, analyzed the changes in the relative defocus values of each quadrant and annular region after wearing the lenses for 6 months and 12 months, and explored the relationship between these changes and the growth of the eye axis.

Results: The group with a small optic zone can generate a stronger myopic defocus effect in the region of 10° - 20°, while the group with a conventional optic zone shows more significant defocus effects in the region of 40° - 53° and the temporal region. In the nasal region, the myopic defocus value of the group with a small optic zone is higher, and the effect is enhanced as the wearing time prolongs. Multiple factors such as age, myopia degree, and pupil diameter are significantly correlated with the growth of the eye axis. Moreover, in different optic zone groups, the influence of each factor on the growth of the eye axis varies. Aspheric orthokeratology lenses with a small optic zone perform better in controlling the growth of the eye axis in adolescents with moderate to high myopia, and this effect is related to multiple ocular parameters.​.

Conclusions: Aspheric orthokeratology lenses with a small optic zone have a better effect on controlling the eye axis of adolescents with moderate to high myopia. This is related to multiple parameters. They may provide a more precise mechanism for myopia control.