Classification of normal corneal topography based on computer-assisted videokeratography

Area of Science:

• Ophthalmology
• Optometry
• Biomedical Engineering

Background:

• Corneal topography is crucial for understanding refractive errors and guiding surgical interventions.
• Standardized classification systems are needed to accurately describe normal corneal shapes.

Purpose of the Study:

• To develop and apply a qualitative classification system for normal corneal topography using computer-assisted videokeratography.
• To analyze the prevalence of different topographic patterns in a cohort of normal corneas.

Main Methods:

• Evaluated topography of 399 normal corneas in 212 subjects using computer-assisted videokeratography.
• Developed a classification system based on color-coded topographic maps.
• Three masked ophthalmologists classified corneas into patterns: round, oval, symmetric bow tie, asymmetric bow tie, and irregular.

Main Results:

• Identified five distinct topographic patterns: round (22.6%), oval (20.8%), symmetric bow tie (17.5%), asymmetric bow tie (32.1%), and irregular (7.1%).
• All corneas exhibited central steepening and peripheral flattening.
• Statistically significant differences were found in keratometric astigmatism among the patterns, but not in spherical equivalent refraction, mean keratometric power, or subject age.

Conclusions:

• A qualitative classification system for normal corneal topography was successfully derived and applied.
• The asymmetric bow tie pattern was the most prevalent in this cohort.
• This classification system is a valuable tool for characterizing normal and potentially pathologic corneal shapes.