Artefact-free topography based scleral-asymmetry

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optometry

Background:

• Corneoscleral topography data is crucial for understanding ocular surface geometry.
• Edge-effect artifacts in topography data can obscure accurate scleral shape analysis.
• Accurate scleral shape assessment is vital for custom contact lens design and fitting.

Purpose of the Study:

• To introduce a novel three-dimensional, non-parametric method for detecting scleral asymmetry.
• To utilize corneoscleral topography data, specifically eliminating edge-effect artifacts for enhanced accuracy.
• To provide a more precise understanding of the scleral shape for clinical applications.

Main Methods:

• Employed a cohort of 88 participants (ages 23-65).
• Processed Eye Surface Profiler data using custom MATLAB codes, removing edge-effect noise via a robust statistical moving median technique.
• Compared raw elevation data and relative elevation derived from best-fit sphere analysis.

Main Results:

• After edge-effect removal, average raw scleral elevations differed significantly between nasal and temporal sides.
• Maximum raw elevation asymmetry was observed towards the nasal side in both eyes.
• Best-fit sphere analysis indicated higher scleral elevation in specific meridians, with maximum asymmetries recorded at distinct angular positions.

Conclusions:

• Corneoscleral topography data requires edge-effect removal for reliable scleral shape prediction.
• The nasal sclera is more elevated than the temporal sclera, influencing the behavior of rotationally symmetric contact lenses.
• Levelled raw elevation provides a more accurate description of scleral shape compared to relative elevation.