"normalized contrast sensitivity": A practical new notation for mainstream contrast sensitivity testing in refractive surgery

Purpose. Not many refractive surgeons use contrast sensitivity, although it is known to be a more sensitive measure of visual function than visual acuity. We introduce a practical ratio notation to facilitate clinical use of contrast sensitivity. Methods. A simple ratio was obtained for each contrast grating patch by dividing the contrast sensitivity of the VectorVision CSV-1000 chart by a population mean. Results. Normalized contrast sensitivities are relative to 1.0, representing the mean. Notations greater than 1.0 indicate percent of contrast sensitivity greater than the normal mean (eg. 1.18 indicates contrast sensitivity 18% greater than the normal mean). Notations less than 1.0 indicate percent contrast less than the normal mean (.eg. .79 indicates 79% of the contrast sensitivity of the normal mean). A sample clinic chart notation may appear as such: OD 1.0, 1.0, 1.18, 1.1 CS OS 1.0, 0.79, 1.0, 0.79 Each column represents the normalized contrast sensitivity for each of the four spatial frequencies (3, 6, 12, 18 cycles/degree). Conclusions. Like visual acuity notation, normalized contrast sensitivity incorporates a relative standard. With wider use of contrast testing in clinical and scientific arenas, questions of visual function in refractive surgery can be better answered.