Low-contrast letter acuity testing captures visual dysfunction in patients with multiple sclerosis

• Published in: Neurology Vol. 64; no. 6; pp. 992 - 995
• Main Authors: BAIER, M. L, CUTTER, G. R, RUDICK, R. A, MILLER, D, COHEN, J. A, WEINSTOCK-GUTTMAN, B, MASS, M, BALCER, L. J
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 22-03-2005
• Subjects: Adult; Biological and medical sciences; Brain - drug effects; Brain - pathology; Brain - physiopathology; Cohort Studies; Contrast Sensitivity - physiology; Disability Evaluation; Female; Humans; Immunomodulators; Interferon beta-1a; Interferon-beta - therapeutic use; Male; Medical sciences; Middle Aged; Multiple Sclerosis - diagnosis; Multiple Sclerosis - drug therapy; Multiple Sclerosis - physiopathology; Multiple sclerosis and variants. Guillain barré syndrome and other inflammatory polyneuropathies. Leukoencephalitis; Neurologic Examination - methods; Neurology; Pharmacology. Drug treatments; Photic Stimulation - methods; Predictive Value of Tests; Quality of Life; Reproducibility of Results; Treatment Outcome; Vision Disorders - diagnosis; Vision Disorders - drug therapy; Vision Disorders - physiopathology; Visual Pathways - drug effects; Visual Pathways - pathology; Visual Pathways - physiopathology; Human; Letter; Multiple sclerosis; Nervous system diseases; Dysfunction; Central nervous system disease; Visual acuity; Capture; Inflammatory disease
• ISSN: 0028-3878; 1526-632X
• DOI: 10.1212/01.WNL.0000154521.40686.63

To evaluate concurrent and predictive validity for low-contrast letter acuity (L-CLA) testing as a candidate visual component for the Multiple Sclerosis Functional Composite (MSFC).
L-CLA testing was conducted in two MS patient cohorts. In the MSFC Validation Study, 137 participants from a Phase III trial of inteferon beta-1a (Avonex) for relapsing-remitting MS were followed. A second cohort included 65 patients with secondary progressive MS who participated in a substudy of the International MS Secondary Progressive Avonex Controlled Trial (IMPACT). The total number of letters read correctly at four contrast levels (100, 5, 1.25, and 0.6%) was correlated with Expanded Disability Status Scale (EDSS), MSFC, Sickness Impact Profile, Multiple Sclerosis Quality of Life Inventory, and brain parenchymal fraction (BPF), as determined by MRI.
Low- and high-contrast letter acuity scores correlated with BPF at follow-up in the MSFC Validation Study (5%: r = 0.40, p < 0.0001; 100%: r = 0.31, p = 0.0002). L-CLA also correlated with EDSS (5%: r = -0.35, p < 0.0001; 1.25%: r = -0.26, p = 0.0003) and MSFC (5%: r = 0.47, p < 0.0001; 1.25%: r = 0.45, p < 0.0001). In the IMPACT Substudy, change in L-CLA scores from baseline to year 1 predicted subsequent change in the EDSS from year 1 to 2 at the 5% (p = 0.0142) and the 1.25% (p = 0.0038) contrast levels, after adjusting for change in MSFC scores from baseline to year 1.
Low-contrast letter acuity (L-CLA) scores demonstrate concurrent and predictive validity in patients with relapsing-remitting and secondary progressive multiple sclerosis (MS). L-CLA testing provides additional information relevant to the MS disease process that is not entirely captured by the Multiple Sclerosis Functional Composite.