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Value of Pelli-Robson contrast sensitivity chart for evaluation of visual system in multiple sclerosis patients.

BACKGROUND AND PURPOSE
The Multiple Sclerosis Functional Composite (MSFC) score, in addition to the commonly used EDSS scale, is one of the standard procedures used for a quantitative evaluation of the clinical state of patients with multiple sclerosis (MS). These methods, however, do not include an evaluation of the visual system. Hence, a search for sensitive tests evaluating the state of the visual system is important. Our study aims to answer the question whether the examination of contrast discrimination by means of the Pelli-Robson method is of any objective value for clinical practice.


MATERIAL AND METHODS
100 Patients presenting with MS and 29 healthy subjects with 100% visual acuity (assessed by means of Snellen's scale) were included in the study. The examination of visual acuity was performed by means of a contrast discrimination chart (Pelli-Robson) according to the instructions provided by the manufacturer.


RESULTS
Contrast discrimination capacity was found to be significantly lower in the group of MS patients than that established in the control group. The same observation holds true for the subgroup of MS patients presenting with normal visual acuity, measured with the Snellen scale. Categorization of results showed that values <1.40 lg of contrast discrimination were not found in healthy subjects.


CONCLUSIONS
The Pelli-Robson contrast discrimination test is a more sensitive procedure for detecting visual disturbances than the visual acuity test according to Snellen. The Pelli-Robson test thus constitutes a valuable supplement of the examination triad routinely involved in the MSFC for evaluation of the clinical status of patients, especially in the dynamic aspect of the outcome measure.