In a study of the impact of multiple sclerosis on vision and eye tissues, African Americans with MS showed more visual impairment and faster thinning of the nerve fibers in the back of the eye than Caucasians with MS. These results add to research findings suggesting that MS can be more severe in African Americans. Studies like this one are crucial to understanding MS progression, for planning and conducting clinical trials, and for finding solutions for African Americans with MS. Dorlan J. Kimbrough, MD, and a multicenter team including grantees funded by the National MS Society report their findings in the Annals of Neurology (Accepted manuscript online: 8 NOV 2014)
Background: Research shows that MS occurs in most ethnic groups, including African-Americans, Asians and Hispanics/Latinos; susceptibility rates vary among these groups. One team previously reported that African Americans tended to have a more aggressive course of disease than Caucasian Americans, were at higher risk for developing mobility impairments, were more likely to develop MS later in life, and were at higher risk for having symptoms restricted to the optic nerve and spinal cord. (Neurology 2004;63:2039-45)
Optical coherence tomography (OCT) is a non-invasive and painless imaging tool for viewing structures such as the retina at the back of the eye. OCT studies have shown that the retinal nerve fiber (which carries visual information before it leaves the back of the eye) layer is different in people with MS than in people without MS, making OCT a useful tool for learning more about the damage caused by MS. For the current study, the team used OCT to determine whether African-Americans with MS have more retinal damage and visual impairment compared to Caucasian-Americans with MS, and also used low and high contrast vision tests (tests that measure the ability to perceive details, indicating visual impairment) to understand differences.
The Study: This multi-center collaborative team -- from Johns Hopkins University, Baltimore; University of Pennsylvania, Philadelphia; University of Texas Southwestern, Dallas; University of California, San Francisco; and New York University, New York City -- recruited 81 African Americans with MS and 606 Caucasians with MS, and 110 controls without MS at three academic hospitals between 2008 and 2012. They compared OCT results, as well as high and low contrast visual acuity. Participants were followed for approximately 2 years.
Retinal nerve fiber layer thickness did not differ among African Americans and Caucasians with MS at the outset of the study. In people without MS, African Americans had greater nerve fiber thickness. However, in this study the retinal nerve fiber layer thinned faster among African Americans with MS when compared to Caucasians with MS, as observed during follow up. The results also show more impaired vision (high contrast visual acuity scores) in African Americans with MS, and a greater loss of low contrast visual acuity per year of disease duration.
Comment: Studies are increasingly indicating that the experience of MS may be more severe in African Americans, and MS prevalence may also be underestimated in this population. Studies such as this one are crucial to understanding MS progression, for planning and conducting clinical trials, and for finding solutions for African Americans with MS.
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