While glaucoma is an eye disease that affects close to 70 million people around the world and 300,000 people in Australia, there is little information about the origins of the condition.
In simple terms, glaucoma relates to an array of eye diseases that impact vision due to damage of the optic nerve. While everyone is at risk of developing glaucoma, the risk increases for those with a family history of the condition, people with high or low blood pressure, people over the age of 50, those with diabetes and people with a previous history of eye injury.
New research from MIT and Massachusetts Eye and Ear has discovered that the condition may actually be an autoimmune disorder. Testing on mice, researchers discovered that the body’s own T cells are responsible for the progressive retinal degeneration seen in the eye condition. The study also found T cells can attack retinal neurons. Researchers are now hopeful new treatment could be developed to block this autoimmune activity.
Read more: Why eye colour can change with age
At present, many treatments of glaucoma focus on lowering pressure in the eyes, although the disease can continue to worsen even after eye pressure has been normalised. Because these observations were also made in mice during the study, researchers believe an immune response was somehow involved.
Upon further testing, they discovered T cells were present in the retinas, a surprising observation given that T cells are typically blocked from entering there. Researchers believe that when eye pressure increases, it allows T cells to get through the protective barrier and into the eye.
What’s remarkable is that in addition to finding unusual immune cells in the eyes of mice with glaucoma, researchers found that when the cells were removed, mice didn’t contract glaucoma. In addition, mice with elevated pressure in their eyes didn’t develop the disease, suggesting that it may be curable.
Other tests found the immune system in mice with glaucoma actually attacked the cells in the eyes because of heat stroke proteins which typically help cells regenerate after injury or stress. These are similar to proteins produced by bacteria, so the body could unintentionally think its fighting an infection.
Analysing human patients with glaucoma, researchers discovered some had five times the normal level of T cells, noting a link between their observations on test mice and humans. They also found the effect is not specific to one type of bacteria and that an exposure to a combination of bacteria can actually generate the T cells that target heat stroke proteins.
The study was published in the Nature Communications Journal, with researchers hopeful their findings could also assist other parts of the body such as the brain that are impacted by autoimmune problems.