Mean shape of the human limbus.

Area of Science:

• Ophthalmology
• Optometry
• Biomedical Engineering

Background:

• The limbus, the border between the cornea and sclera, plays a crucial role in ocular health and surgical procedures.
• Understanding the limbus's topographic shape is essential for accurate ophthalmic measurements and interventions.

Purpose of the Study:

• To characterize the mean topographic shape of the normal human limbus.
• To investigate the influence of age and refractive power on limbus topography.

Main Methods:

• A prospective case series involving 74 participants (aged 20-84 years) with no prior ocular surgeries.
• Corneoscleral topography was performed using an Eye Surface Profiler to capture anterior eye height data.
• The limbus was demarcated and fitted to various models (circle, ellipse, Fourier series) to determine the best descriptive fit, with white-to-white corneal diameter also recorded.

Main Results:

• The 2nd-order Fourier series provided the most accurate model for describing the human limbus shape.
• A mean difference of 0.33 mm ± 0.24 mm was observed between the topographic limbus diameter and white-to-white corneal diameter.
• While limbus shape varied significantly between eye quadrants, it showed no statistically significant correlation with age groups or refractive error (myopia vs. emmetropia).

Conclusions:

• The human limbus exhibits an asymmetrical, person-dependent shape.
• Limbus topography is not influenced by age or the refractive power of the eye.