The prevalence of myopia has consistently increased with time; however, little research examines how the condition affects in vivo anterior sclera shape. Researchers recently found that high myopes exhibited a different anterior eye shape than emmetropes, with greater sagittal height in the nasal corneal periphery and anterior sclera and less nasal-temporal asymmetry of sagittal height and axial radius of curvature. They suggested asymmetric growth of the eye associated with myopia development as a potential underlying reason.
This prospective study analyzed nasal data from 39 participants and temporal data from 43. A team assessed sagittal height and axial radius of curvature of regions over the nasal and temporal corneal periphery and anterior sclera.
The investigators observed greater sagittal height in the nasal sides of the surfaces of the corneal periphery and anterior sclera in high myopes than in emmetropes across all regions (2.44±0.07mm and 2.21±0.04mm, respectively) but no significant differences between low to moderate myopes with emmetropes or with high myopes. They noted that no significant refractive group differences occurred for temporal anterior eye surface height. They added that high myopes had less nasal-temporal asymmetry of sagittal height than emmetropes (0.20±0.07mm and 0.46±0.06mm, respectively) and less nasal-temporal axial radius of curvature asymmetry than emmetropes (0.35±0.08mm and 0.71±0.08mm, respectively) across all regions.
“These findings have implications for design of contact lenses, particularly soft and larger rigid lenses such as mini-sclerals,” the study authors concluded in their paper.
Niyazmand H, Read SA, Atchison DA, et al. Anterior eye shape in emmetropes, low to moderate myopes, and hih myopes. Cont Lens Ant Eye. August 21, 2020. [Epub ahead of print].