Derivation of corneal flattening factor, p-value

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optometry

Background:

• Corneal topography is crucial for refractive surgery and contact lens fitting.
• Existing methods may not provide all necessary parameters, such as the corneal p-value and apical radius (ro).
• Accurate calculation of these parameters is essential for precise optical modeling.

Purpose of the Study:

• To derive a mathematical equation for calculating the corneal p-value.
• To develop a simplified computational method for corneal p-value and apical radius (ro) determination.
• To validate the accuracy of the developed method.

Main Methods:

• Derivation of a novel mathematical equation using central/peripheral corneal radii and semichord diameters.
• Development of a GWBASIC computer program for simplified calculations.
• Validation using Douthwaite's modified keratometer and assessment of correlation.

Main Results:

• A simplified mathematical formula was established for corneal p-value calculation.
• A computer program was successfully created to compute corneal p-value and apical radius (ro).
• Good correlation was observed between the program's results and measurements from Douthwaite's modified keratometer.

Conclusions:

• The developed mathematical equation and computer program provide an accurate method for determining corneal p-value and apical radius (ro).
• This tool is valuable for topographic keratometers that only supply central and peripheral radii.
• The method enhances the utility of existing keratometry data for comprehensive corneal analysis.