Glaucoma is one of the most common causes of blindness around the world. The disease slowly damages the optic nerve, which is the nerve that carries visual information from the eye to the brain. When this nerve is harmed, vision gradually fades.
Many people do not notice the problem in the early stages because the loss of sight usually happens slowly and without pain. By the time symptoms appear, the damage is often already serious and cannot be reversed. Because of this, glaucoma is responsible for permanent vision loss in millions of people worldwide.
Most cases of glaucoma are linked to high pressure inside the eye. The eye constantly produces fluid that must drain out properly. When the drainage system does not work well, pressure can build up.
Over time, this pressure can damage the optic nerve. For decades, treatments for glaucoma have mainly focused on lowering this pressure. Doctors usually prescribe eye drops, laser treatments, or surgery to help reduce the pressure and protect the nerve.
However, these treatments do not work equally well for everyone. Some people continue to lose vision even when their eye pressure is well controlled. Because of this, scientists have been searching for other factors that may contribute to glaucoma and new ways to slow the disease.
A research team from Karolinska Institutet in Sweden has now explored a different explanation. Instead of focusing only on eye pressure, the scientists studied the metabolism of the retina.
The retina is the light‑sensitive layer at the back of the eye that detects light and sends signals to the brain through the optic nerve. Healthy metabolism is essential for the retina because its cells need a steady supply of energy to function properly.
The researchers were particularly interested in a substance called homocysteine. Homocysteine is a natural chemical found in the body and is involved in normal metabolism.
In the past, some studies suggested that high levels of homocysteine might be linked to glaucoma and could possibly damage nerve cells. Because of this idea, scientists wanted to know whether homocysteine actually plays a direct role in the disease.
To investigate this question, the team carried out a series of experiments. They studied rats with glaucoma and increased the levels of homocysteine in their bodies to see if the disease became worse. Surprisingly, the researchers found that the higher levels did not make the glaucoma more severe. This suggested that homocysteine might not be causing the disease after all.
The scientists also examined information from human patients with glaucoma. They looked at whether people with higher levels of homocysteine in their blood developed glaucoma faster.
They also studied people who were genetically more likely to have higher homocysteine levels. The results again showed no clear connection between homocysteine and the worsening of glaucoma.
These findings led the researchers to a different conclusion. Instead of being the cause of glaucoma, homocysteine might simply be a sign that something else is happening inside the eye. The team began to suspect that the real problem could be related to the way the retina uses certain vitamins that support metabolism.
When the researchers studied the retina more closely, they discovered signs that the tissue was not processing vitamins properly. This problem appeared to slow down important metabolic processes in the retina.
When metabolism slows, the cells become weaker and more vulnerable to damage. In glaucoma, this weakness may make the optic nerve more likely to deteriorate.
Based on this idea, the scientists asked an important question. If the retina is struggling to use certain vitamins, could providing extra vitamins help restore healthy metabolism and protect the nerve?
To test this possibility, the researchers gave animals with glaucoma a combination of several vitamins and nutrients that support metabolic activity.
The mixture included vitamin B6, vitamin B9 (also known as folate), vitamin B12, and choline. These nutrients are already known to play important roles in how the body processes energy and maintains healthy nerve cells.
The results were striking. In mice that had a slowly progressing form of glaucoma, the damage to the optic nerve stopped completely after receiving the vitamin mixture. In rats with a faster‑moving form of the disease, the treatment significantly slowed the progression of nerve damage.
One of the most surprising findings was that the improvement happened without lowering eye pressure. This means the vitamins appeared to work through a completely different pathway from traditional treatments. Instead of affecting the pressure inside the eye, they helped support the metabolic health of the retina.
Dr. James Tribble, assistant professor at Karolinska Institutet and co‑lead author of the study, explained that changes in homocysteine levels may reflect a loss of vitamin‑dependent metabolic activity in the retina. By restoring these vitamins, the researchers may be helping the retina regain its normal metabolic function.
Because the results were so encouraging in laboratory studies, the researchers have already begun testing the treatment in people. A clinical trial is now underway in Sweden at S:t Eriks Eye Hospital in Stockholm.
The trial will include patients with primary open‑angle glaucoma, which is the most common form of the disease, as well as patients with pseudoexfoliation glaucoma, a more aggressive type.
If the clinical trial confirms the benefits seen in animals, the discovery could change how doctors approach glaucoma treatment. Instead of focusing only on lowering eye pressure, future therapies might also aim to protect the retina and optic nerve by improving their metabolic health.
This research also adds to growing evidence that nutrition and metabolism play important roles in diseases that affect the nervous system. In some cases, simple nutrients that the body already uses every day may help support the health of delicate tissues like the retina.
If you care about eye health, please read studies about how vitamin B may help fight vision loss, and MIND diet may reduce risk of vision loss disease.
For more information about eye disease, please see recent studies about how to protect your eyes from glaucoma, and results showing this eye surgery may reduce dementia risk.
The findings of this research were published in the journal Cell Reports Medicine.
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