Abnormal adaptation of visual contrast sensitivity in multiple sclerosis patients

Area of Science:

• Neuroscience
• Ophthalmology
• Clinical Vision Science

Background:

• Multiple sclerosis (MS) patients with 20/20 visual acuity often report subjective visual deficits.
• Previous research indicated MS-related reduced contrast sensitivity, despite preserved visual acuity.

Purpose of the Study:

• To investigate if abnormal contrast adaptation during testing contributes to the measured contrast sensitivity depression in MS patients.
• To determine the relationship between contrast sensitivity deficits and contrast adaptation abnormalities in MS.

Main Methods:

• Assessed contrast sensitivity and contrast adaptation in multiple sclerosis patients.
• Compared adaptation responses in patients with and without contrast sensitivity loss.
• Examined if adaptation abnormalities were specific to spatial frequency bands affected by sensitivity loss.

Main Results:

• Contrast adaptation was found to be normal (slight and/or slow) in MS patients, refuting the hypothesis of rapid adaptation causing depressed sensitivity.
• Depressed contrast sensitivity did not strongly correlate with abnormal contrast adaptation.
• Some patients with normal contrast sensitivity exhibited abnormal adaptation, and vice versa.

Conclusions:

• The observed depression in contrast sensitivity in multiple sclerosis patients is unlikely due to abnormal adaptation during testing.
• Contrast sensitivity deficits and adaptation abnormalities in MS appear to be dissociated phenomena.
• Further research is needed to understand the underlying mechanisms of visual dysfunction in MS.