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The evaluation of multiple sclerosis through static chromatic perimetry

University of British Columbia

The purpose of the present study was to examine whether or not luminance thresholds through static, chromatic perimetry could be used to distinguish visual threshold losses in multiple sclerosis from that of normal functioning. It was proposed that threshold losses would be greater at both the fovea and near foveal eccentricities due to the assumption that the cone system, unlike the rods, would be the most effected by MS. Twenty-two MS patients and thirty age matched normals were tested on an extensively modified version of the Fieldmaster F225 Automatic Perimeter. Thresholds were established for an achromatic, red, and blue stimulus along a 195 - 15 degree meridian. Testing was done using a 45 apostilb background, to which the subjects were preadapted prior to testing. Results indicated that there was extensive cone involvement (loss in chromatic thresholds) for the MS subjects. Significant differences existed at the fovea between normal and clinically definite subjects but not between normal and probable. Correlational analyses indicated great functional changes in retinal sensitivity for the MS patients. Similar results were obtained between MS patients with and without optic neuritis. Discriminant analyses indicated that the red filter could correctly classify 86.27% of the normals and MS patients with few false positives or negatives. Log threshold difference values between the fovea and 30 degree nasal eccentricity were used to determine a threshold value which could separate normal profiles from MS profiles. The typical "swiss cheese" defects reported in the clinical literature were found only for the achromatic and blue filters. No irregular profiles were found for the red filter. A possible theoretical model based on the results was discussed. Limitations of the study as well as possible future research were also discussed.

Text

2010-08-13

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http://hdl.handle.net/2429/27364

Psychology

University of British Columbia

Graduate