Contrast sensitivity measurements in acute and resolved optic neuritis.

We measured contrast sensitivity by means of Arden grating plates in 41 eyes with acute optic neuritis and in 51 eyes with resolved optic neuritis. The scores were abnormal in 93% of eyes in the acute phase and 78% in the resolved phase irrespective of visual acuity. Even when acuity improved to 6/7.5 or better with resolution of the neuritis, 67% of eyes still showed abnormal contrast sensitivity. Since Snellen acuity represents just one point at the high spatial frequency end of the contrast sensitivity function, a patient in whom acuity improves to 6/6 with resolution of optic neuritis may still have difficulty seeing objects of lower relative contrast or at lower spatial frequencies.