In the news: Low Vitamin D Linked to NMOSD; Is Low MPOD A Risk for Glaucoma?

Lower Vitamin D Levels Observed in Neuromyelitis Optic Spectrum Disorder

Neuromyelitis Optic Spectrum Disorder (NMOSD) is a condition characterized by painful eye movement and temporary loss of vision in one eye. NMOSD can be the first indication of multiple sclerosis (MS).

Studies have shown that those with MS often have lower vitamin D levels, and that individuals with lower levels of vitamin D either due to genetics or diet may be more likely to develop MS. Because vitamin D plays a regulatory role in the immune system, it contributes to the development and prevention of autoimmune diseases such as MS.

Researchers recently conducted a meta-analysis(1) of 6 observational studies which included 914 participants (319 with NMOSD) to determine whether vitamin D levels were lower in those with the condition than in those without NMOSD.

Serum vitamin D levels were significantly lower in NMOSD patients vs. healthy controls (p<0.001). Subgroup analyses showed significantly lower levels of the vitamin in NMOSD vs. controls in studies with sample sizes larger than 100, in high quality studies, and in those on immunosuppressive drugs. There was no significant publication bias in this seemingly robust meta-analysis (P>0.05).

It is possible, however, that those with a painful eye condition are outdoors less and thus are not making vitamin D from sufficient sunlight exposure. “Randomized controlled trials with large samples will further confirm whether the association is casual and modifiable”, according to the authors.

Low MPOD Linked to Glaucoma in Older Women

Emerging evidence suggests that low macular pigment optical density (MPOD) may influence the risk of glaucoma. MPOD can be modified by consuming more of the carotenoids lutein and zeaxanthin. Large cohort studies have found decreased glaucoma risk among participants reporting higher intakes of carotenoid-rich foods. As powerful antioxidants, carotenoids may help prevent oxidative stress which has been implicated in the development of glaucoma.

Investigators recently evaluated whether MPOD was associated with primary open-angle glaucoma (POAG) among older women in the Carotenoids in Age-Related Eye Disease Study 2 (CAREDS2).

CAREDS2 is a study examining the relationships between MPOD and AMD and cataract among women from three clinical sites in the Women’s Health Initiative Observational Study.

CAREDS2 uses outcome measures such as OCT, disc photos, visual field testing and medical records to assess glaucoma. In the current study, MPOD was measured with customized heterochromatic flicker photometry.

In this study(2), glaucomatous eyes were found to have 25% lower MPOD vs. eyes without glaucoma (P=0.01). These findings were like the associations seen between POAG measured 15 years earlier in CAREDS1 among all eyes.

Results were similar after excluding eyes with macular degeneration, but no longer statistically significant. This may have been due to sample size limitations, according to the investigators.

The overall body of evidence, state the authors, supports further research into a possible protective role for MPOD in glaucoma.

References

1. Zhu Y, et al. Vitamin D status and neuromyelitis optica spectrum disease: A systematic review and meta-analysis. Clin Neurol Neurosurg. 239:108190, 2024.
2. You L, et al. Low macular pigment optical density is associated with manifest primary open-angle glaucoma in older women. Cur Develop Nutr. Epub May 25, 2024.