A vitamin supplement that improves metabolism in the eye appears to slow
down damage to the optic nerve in glaucoma. Promising results have been
published in the journal Cell Reports Medicine. The researchers behind the
study have now started a clinical trial on patients.
In glaucoma, the optic nerve is gradually damaged, leading to vision loss
and, in the worst cases, blindness.
High pressure in the eye drives the
disease, and eye drops, laser treatment or surgery are therefore used to lower
the pressure in the eye and thus slow down the disease. Unfortunately, however,
the effect varies. Glaucoma researchers have long theorised that the substance
homocysteine is somehow relevant to understanding the disease. Now, researchers
at KarolinskaInstitutet have investigated the role of homocysteine in several
ways.
In the current study, the researchers discovered that when rats with
glaucoma were given elevated levels of homocysteine, their disease did not
worsen.
The researchers also found that high levels of homocysteine in the
blood of people with glaucoma did not correlate with how quickly the disease
progressed, and that glaucoma was not more common in people with a genetic
susceptibility to forming high levels of homocysteine. Based on these findings,
the researchers concluded that homocysteine does not drive the disease but is a
consequence of it.
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.
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.