Myopia progression appears to be driven by disrupted vision-guided eye growth, in which environmental exposure and optical signaling interact with genetic susceptibility, according to an integrative review.

Victor Opoku-Yamoah, PhD, of the University of Waterloo, and colleagues synthesized evidence from experimental, epidemiologic, and clinical studies to describe how near work, reduced outdoor exposure, and genetic susceptibility contribute to myopia development and progression.

Methods and Findings

The review integrates data across animal models, observational studies, and clinical trials to outline a unified mechanism in which environmental exposures induce optical defocus that is translated into retinal and molecular signals regulating eye growth.

Experimental models showed that disrupting visual feedback produces rapid myopic changes. In form-deprivation models, chicks developed up to −9 diopters of myopia within 5 days, and primates developed approximately −5 diopters over 17 weeks, with associated vitreous chamber elongation, scleral thinning, and choroidal atrophy.

Peripheral retinal defocus emerged as a key regulator of axial growth. Hyperopic defocus accelerated elongation, whereas myopic defocus slowed growth, forming the basis for optical control strategies.

Environmental findings aligned with these mechanisms. Near work was associated with accommodative lag and hyperopic retinal blur that promotes axial elongation. In a study of 605 patients aged 6 to 14 years, myopia progression increased following correction with minus lenses, with greater divergence from emmetropic controls over time.

Outdoor exposure showed a protective association. One additional hour outdoors daily was linked to an approximate 2% reduction in incident myopia, and at least 14 hours per week was associated with lower risk.

Genetic factors further modified these effects. Variants, including those involving the VIPR2 gene, interacted with environmental exposure such as time outdoors to influence axial length, contributing to variability in progression among patients.

Interventions

Interventions targeting these pathways were associated with reduced progression:

• Orthokeratology reduced axial elongation by roughly 33% over 7 years compared with single-vision correction

• Multifocal soft contact lenses reduced axial elongation by 29% and myopia progression by 50% over 2 years

• Spectacle lens designs, including defocus incorporated multiple segments and highly aspherical lenslets, reduced refractive progression and axial elongation in clinical trials

• Low-dose atropine (0.01%–0.05%) reduced progression by 30% to 60%

• Increased outdoor exposure was associated with reduced onset of myopia

Treatment effects varied by patient characteristics, with greater benefit observed in those with higher accommodative lag, increased near work exposure, and earlier stages of progression.

Limitations

The review included heterogeneous evidence from experimental, observational, and clinical studies, with variability in populations and methodologies. Conflicting findings regarding accommodative mechanisms highlight the need for standardized longitudinal research.

Conclusion

The findings support a biologically grounded, individualized approach to myopia management that integrates environmental, optical, and genetic factors.

“Optimal control requires tailored and combined strategies,” the authors wrote.

Disclosures: The authors reported no conflicts of interest.

Source: Eye & ENT Research