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Reliability of visual performance measurement under optical degradation
1Department of Optometry and Visual Science, City University, London, UK.
Summary
Bifocal contact lenses reduce visual performance. Reliability of vision tests decreased with poorer performance, suggesting a link between visual degradation and test accuracy for contact lens wearers.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Bifocal contact lenses are used to correct presbyopia.
- Previous research suggests potential impacts on visual performance.
Purpose of the Study:
- To assess the impact of bifocal contact lenses on visual performance.
- To evaluate the reliability of visual performance measures with bifocal contact lens wear.
Main Methods:
- Experienced subjects wore three types of bifocal contact lenses.
- Measurements included monitor-based contrast sensitivity, Pelli-Robson contrast threshold, and high/low-contrast visual acuity.
- Tests were repeated to assess reliability.
Main Results:
- Bifocal contact lenses reduced visual performance in both distance and near conditions.
- Test-retest reliability of visual performance measures decreased with declining visual acuity.
- Repeatability coefficients increased as average visual performance declined.
Conclusions:
- The reliability of visual performance tests is reduced with bifocal contact lens wear.
- Reduced reliability may be associated with visual degradation, relevant for practitioners.
- Pelli-Robson contrast thresholds correlated with spatial frequency.