Comparative analysis of the effectiveness of orthokeratology and bifocal soft contact lenses with high add power

Progressive myopia in children is associated with a risk of ophthalmic pathology in adulthood. Orthokeratology lenses (OKLs) and bifocal/ multifocal soft contact lenses (BSCLs) are widely used for optical control of myopia. Comparative evaluation of their effectiveness is necessary for personalizing the choice of myopia control method in children. Purpose: to compare the change in spherical equivalent refraction (SE) and axial length (AL) in children aged 8–13 years with progressive myopia using OKLs (including those with reduced BOZD/fixed RZD) and BMCLs. Material and methods. The prospective study included 160 children aged 8–13 years (median age 11 years). SE was 1.00–6.00 D, astigmatism £ 0.75 D. To control myopia, children were offered a choice of defocus spectacles, BSCL, and OKL. Participants who chose contact correction were assigned to the BMCL (n = 70) or OKL (n = 90) groups. AL and SE measurements under cycloplegia were performed at baseline and 12 months after discontinuation of OKL wearing. Statistical analysis was performed taking into account clustering by eyes (GEE); the Brunner — Munzel/χ²/Fisher’s exact test was used for comparison. Results. Over 12 months, a statistically significant increase in AL (p < 0.001) and a shift in SE towards increased myopia occurred in both groups (BSCL: p = 0.008; OKL: p = 0.002). When stratifying by the degree of myopia, it was found that with mild myopia, SE increased in both groups (BSCL, p < 0.001; OKL, p = 0.017); with moderate myopia, no significant changes in SE were found (p = 0.125 and p = 0.099). With mild myopia, there were no significant intergroup differences in AL levels initially/after one year (p = 0.526/0.933); however, the absolute increase in AL over one year was greater in the OKL group (p = 0.011). With moderate myopia, the initial AL was slightly higher in the BSCL (p = 0.067); after one year, intergroup differences in AL were statistically insignificant (p = 0.141). The relationship between AL and SE changes: there is no correlation for the cohort as a whole (ρ = 0.07; p = 0.299); In OKL there was no association (ρ = 0.10; p = 0.326), in BSCL there was a tendency towards a positive association (ρ = 0.21; p = 0.07); no intergroup differences in the strength/direction of the association were found (p = 0.115). A 5.7 % dropout was observed in the BSCL group, while in the OKL group it was 0.0 % (p = 0.035). Conclusion. OKL and BSCL demonstrated comparable clinical efficacy in slowing down axial elongation in children aged 8–13 years over the course of a year. No significant differences in AL were found in the presence of mild myopia with OKL and BSCL; intergroup differences were also not proven with moderate myopia. According to the literature, the efficacy of standard OKL (SOKL) is higher in patients with moderate myopia, while the effect is weaker in patients with mild myopia. Since SOKL was not a separate observation group in our study, the comparisons are indirect. Prospective, long-term studies are required to accurately evaluate the comparative effectiveness of three approaches to myopia control over the long term.