Impact of visual discomfort symptoms on SDMT performance among persons with MS.

BACKGROUND

Visual problems are common among persons with multiple sclerosis (MS) and may interfere with the assessment of cognitive functioning using visually mediated neuropsychological tests. The current study explored visual discomfort symptoms among persons with MS compared to healthy controls (HCs), using the Visual Discomfort Scale (VDS), which measures somatic and perceptual visual discomfort symptoms that interfere with reading.

METHODS

Eighty-nine persons with MS and 30 HCs completed the VDS and the Symbol Digit Modalities Test (SDMT), a visually mediated test of information processing speed and gold standard for screening for MS-related cognitive dysfunction.

RESULTS

Persons with MS endorsed higher frequencies of visual discomfort symptoms, including seeing the text or background moving or fading, headache/eye soreness, blurriness/diplopia, having to re-read, and slow reading, compared to HCs. More frequent visual discomfort symptoms were associated with worse performance on the SDMT. For participants with MS reporting moderate/high levels of visual discomfort symptoms, having a longer disease duration or progressive disease courses were correlated with worse performance on the SDMT.

CONCLUSION

It is important for clinicians to ask about specific visual discomfort problems that the patient experiences when interpreting a visually-mediated neuropsychological test such as the SDMT, especially for MS patients with longer disease duration or a progressive disease course.