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Contact lens base curve prediction from videokeratography
J S Chan1, R B Mandell, L Johnson
1Morton D. Sarver Laboratory for Contact Lens and Cornea Research, School of Optometry, University of California, Berkeley, USA.
Summary
Videokeratography, including corneal eccentricity, can predict the relationship between rigid gas permeable contact lenses and the cornea. This improves upon predictions based solely on central corneal measurements for better lens fitting.
Area of Science:
- Ophthalmology
- Optometry
- Biomedical Engineering
Background:
- Accurate fitting of rigid gas permeable (RGP) contact lenses is crucial for visual acuity and ocular health.
- The relationship between the RGP lens and the cornea influences lens centration, movement, and comfort.
- Videokeratography provides detailed corneal topography, but its predictive value for RGP lens fitting requires further investigation.
Purpose of the Study:
- To evaluate if videokeratography can predict the fluorescein pattern, indicating the contact lens to cornea-bearing relationship.
- To compare the predictive accuracy of videokeratography parameters against empirical fluorescein pattern assessment.
Main Methods:
- Nineteen participants wearing RGP lenses were tested with seven different base curve lenses.
- Fluorescein patterns were analyzed to determine the experimental alignment (EA).
- Videokeratography data, including central curvature and eccentricity, were used to calculate theoretical alignment (TA) and simulated keratometric (KA) readings.
Main Results:
- The mean difference between TA and EA lens choices was -0.01 +/- 0.04 mm.
- The mean difference between KA readings and EA lens choice was 0.11 +/- 0.05 mm.
- Inclusion of eccentricity from videokeratography improved prediction accuracy.
Conclusions:
- Videokeratography, particularly incorporating corneal eccentricity, enhances the prediction of the base curve to cornea relationship for RGP lenses.
- This offers a more precise method for predicting lens fit compared to using only central corneal measurements.
- The findings support the use of advanced videokeratography in optimizing RGP contact lens fitting.