Contrast sensitivity testing measures the ability to detect objects that differ only slightly in brightness from their background. It assesses visual function beyond standard high-contrast acuity charts.
Test Formats
Common methods use charts with stripes or letters that decrease in contrast or computer-based presentations of low-contrast patterns. The lowest contrast at which the target can be seen is recorded at various spatial frequencies.
- Provides a curve showing performance across different detail sizes
- Testing can be done monocularly and binocularly
- Controlled lighting and test distance are important
- May use charts such as Pelli-Robson or sine-wave gratings
Clinical Importance
Reduced contrast sensitivity is common in conditions like cataract, glaucoma, and early macular disease, even when visual acuity is relatively good. Results help explain visual complaints such as difficulty in low light or fog.
- Useful in assessing functional outcomes after surgery or treatment
- Supports decisions about fitness for driving and certain occupations
- Changes over time can indicate disease progression
- Interpretation considers age-related normative data
