Reliability of the Cambridge Low Contrast Gratings.

We examined the reliability of the Cambridge Low Contrast Gratings over four sessions at intervals of 1 hour, 1 day and 1 week. The 95% ranges of difference scores were found to be +/- 10.3 and +/- 10.5 test units for left and right eyes respectively. These reliability estimates span almost one-quarter of the test's dynamic range and one-third of the subjects' performance range. Practice effects were not found to be significant. Though previous reports have emphasized the usefulness of the Cambridge Gratings in screening for eye disease, caution is advised when interpreting changes that occur over time.