Region-specific relationships between refractive error and ciliary muscle thickness in children

Area of Science:

• Ophthalmology
• Refractive Error Research
• Anatomy

Background:

• Refractive error, such as myopia and hyperopia, significantly impacts visual acuity.
• The ciliary muscle plays a crucial role in accommodation and its structural characteristics may be related to refractive states.

Purpose of the Study:

• To investigate the relationship between refractive error and ciliary muscle thickness in specific regions.
• To explore regional differences in ciliary muscle morphology associated with myopia and hyperopia in children.

Main Methods:

• Utilized anterior segment optical coherence tomography to measure ciliary muscle thickness at various points (CMT1, CMT2, CMT3, CMTMAX) in cycloplegia.
• Determined cycloplegic spherical equivalent refractive error (SPHEQ) using an autorefractor.
• Employed multilevel regression models to analyze associations between ciliary muscle dimensions and refractive error.

Main Results:

• Spherical equivalent refractive error (SPHEQ) showed significant associations with ciliary muscle thickness at 2 mm (CMT2) and 3 mm (CMT3) posterior to the scleral spur.
• Apical ciliary muscle fibers, calculated by subtracting CMT2 from CMT1 and CMTMAX, were significantly related to SPHEQ.
• Posterior ciliary muscle fibers (CMT2, CMT3) were thicker in myopic children, whereas apical fibers (CMT1, CMTMAX) were thicker in hyperopic children.

Conclusions:

• The study suggests that posterior ciliary muscle regions are thicker in myopia, while apical regions are thicker in hyperopia among children.
• Findings indicate a potential novel association between a thicker apical ciliary muscle and hyperopia.