A specific vitamin supplement appears to slow glaucoma-related optic nerve damage, even without lowering eye pressure.
A simple vitamin supplement that boosts eye metabolism may hold the key to slowing damage from glaucoma, a leading cause of blindness. New research published in Cell Reports Medicine shows that this supplement could help protect the optic nerve, which is gradually damaged by the disease. The findings are strong enough that scientists have already begun a clinical trial involving human patients.
Glaucoma causes slow but progressive damage to the optic nerve, often leading to vision loss and, in severe cases, total blindness. The main culprit is increased pressure inside the eye. Treatments like eye drops, laser therapy, or surgery aim to lower this pressure, but results can vary widely from person to person.
For years, scientists have wondered whether a molecule called homocysteine might be part of the puzzle. Now, researchers at the Karolinska Institutet have taken a closer look. Surprisingly, when they increased homocysteine levels in rats with glaucoma, the disease did not get worse.
They then looked at people with glaucoma and found something just as interesting. High levels of homocysteine in the blood were not linked to faster disease progression. Even people genetically inclined to produce more homocysteine were not more likely to develop glaucoma. These results suggest that homocysteine is not causing the damage, but may instead be a sign that something else is going wrong in the eye.
Metabolic Clues in the Retina
Since homocysteine is a natural part of the body’s metabolism, the researchers wanted to investigate metabolic pathways involving homocysteine in both rodents and humans with glaucoma. They then saw several abnormalities, the most important of which were metabolic changes linked to the retina’s ability to use certain vitamins. This change meant that metabolism was slowed down locally in the retina – and this played a role in the development of the disease.
‘Our conclusion is that homocysteine is a bystander in the disease process, not a player. Altered homocysteine levels may reveal that the retina has lost its ability to use certain vitamins that are necessary to maintain healthy metabolism. That’s why we wanted to investigate whether supplements of these vitamins could protect the retina,’ says co-lead on the paper James Tribble, researcher and assistant professor at the Department of Clinical Neuroscience at Karolinska Institutet.
Promising Results in Animal Models
In experiments on mice and rats with glaucoma, the researchers gave supplements of the B vitamins B6, B9, and B12, as well as choline. This had a positive effect. In mice that had a slower developing glaucoma, the damage to the optic nerve was completely halted. In rats, which had a more aggressive form of the disease with faster progression, the disease was slowed down.
In these experiments, eye pressure was left untreated, which the researchers highlight as particularly interesting – it suggests that the vitamin mix affects the disease in a different way than lowering eye pressure does.
‘The results are so promising that we have started a clinical trial, with patients already being recruited at St Eriks Eye Hospital in Stockholm,’ says James Tribble.
Both patients with primary open-angle glaucoma (slower progression) and pseudoexfoliation glaucoma (faster progression) are included.
Reference: “Dysfunctional one-carbon metabolism identifies vitamins B6, B9, B12, and choline as neuroprotective in glaucoma” by James R. Tribble, Vickie H.Y. Wong, Kelsey V. Stuart, Glyn Chidlow, Alan Nicol, Anne Rombaut, Alessandro Rabiolo, Anh Hoang, Pei Ying Lee, Carola Rutigliani, Tim J. Enz, Alessio Canovai, Emma Lardner, Gustav Stålhammar, Christine T.O. Nguyen, David F. Garway-Heath, Robert J. Casson, Anthony P. Khawaja, Bang V. Bui and Pete A. Williams, 8 May 2025, Cell Reports Medicine.
DOI: 10.1016/j.xcrm.2025.102127
The study is funded by the Swedish Research Council, the Swedish Eye Health Fund, the Jeansson Foundations, the Crown Princess Margareta Foundation for the Visually Impaired, the Åke Wiberg Foundation and the Petrus & Augusta Hedlund Foundation, among others.
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