Ocular dimensions and refraction in Tibetan children

Area of Science:

• Ophthalmology
• Pediatric Optometry
• Refractive Error Development

Background:

• Refractive errors are a significant global health concern, particularly in pediatric populations.
• Understanding emmetropization is crucial for preventing visual impairment and myopia progression.
• Tibetan children represent a unique ethnic group with distinct genetic and environmental factors that may influence ocular development.

Purpose of the Study:

• To investigate refractive error development and ocular biometry in Tibetan children aged 6 to 16 years.
• To identify factors contributing to emmetropization in this specific ethnic group.
• To analyze changes in crystalline lens power and axial length with age.

Main Methods:

• Cross-sectional study of 404 Tibetan children (aged 6–16 years) in Kathmandu, Nepal.
• Ophthalmic examinations included retinoscopy, keratometry, A-scan ultrasonography, and video ophthalmophakometry.
• Refractive error, axial length, corneal curvature, and lens parameters were measured.

Main Results:

• Mean refractive error decreased from +1.11 D at age 6 to +0.63 D at age 16.
• Myopia prevalence was 3.9%; 95.5% had refractive errors between -0.50 D and +1.50 D.
• Crystalline lens power decreased by 2.59 D, while vitreous chamber depth increased by 0.69 mm.

Conclusions:

• The balance between decreasing crystalline lens power and increasing vitreous length is key to emmetropization in Tibetan children.
• Tibetan children exhibit a strong tendency towards emmetropia during childhood.
• Findings contribute to understanding ethnic variations in refractive development and emmetropization processes.