Glaucoma is a widespread eye condition that can cause blurred vision, blind spots, or complete vision loss. It does so by damaging a bundle of neurons in the back of your eye called the optic nerve. Consequently, this damage hinders the ability of this nerve to transmit visual information from the eye to the brain. The reason for this damage is thought to be due to an accumulation of fluid in the eye, which increases pressure inside the ocular cavity. This, in turn, creates blind spots in the patient’s field of vision that gradually widen over time, otherwise known as glaucoma.
Regrettably, more than 3 million Americans have glaucoma, the leading cause of blindness in adults living in the USA. Despite this, there is still no treatment to reverse the loss of vision incurred before glaucoma is diagnosed.
Now, a study from researchers at the University of Maryland identifies new stem cells in the eye in the specific region where glaucoma damages the optic nerve. The team states their findings present a new theory on why the most common form of glaucoma may develop. Furthermore, it may also provide new ways to treat the disease. The study is published in the journal Proceedings of the National Academy of Sciences.
Cause of glaucoma still unknown
Previous studies show the optic nerve is located in the back of the eye where it transfers visual data from the retina to the vision centers of the brain using electrical impulses. A potentially disabling disease, glaucoma is the result of damage to this nerve.
Subsequently, as the optic nerve deteriorates, blind spots start to appear in the person’s vision. For reasons that doctors don’t fully understand, this optic nerve damage is usually related to increased pressure in the eye. Unfortunately, even though this condition requires lifelong treatment the full pathology of glaucoma is still unknown.
Stem cells found in the optic nerve
Presently the University of Maryland team is investigating a narrow band of tissue called the optic nerve lamina. This lamina or ‘sheet’ is less than 1 millimeter wide and forms a partition between the retina at the back of the eye and the optic nerve. Importantly, the optic nerve lamina is where most of the damage caused by glaucoma occurs.
The current study identifies a stem cell niche in the optic nerve lamina that helps nourish and support the optic nerve. Specifically, this neural progenitor cell niche is capable of producing every type of microglia, a support cell in the brain crucial for nerve cell repair and replacement in the central nervous system. Thus, these lamina stem cells may well support the optic nerve and vision in the same way.
How these cells cause glaucoma
Similarly, these neural progenitor stem cells may also be responsible for insulating the long retinal nerve fibers immediately after they leave the eye and connect to the brain. Indeed, it could possibly be this very action these stem cells use to enable and preserve vision.
The group posits that these neural progenitor cells must be present in the optic nerve tissue at birth, remaining there for decades to help protect the nerve fibers that form the optic nerve. They go on to add that without these protective stem cells, these crucial nerve fibers may start to deteriorate under the constant forces being exerted on them. As a result, this deterioration precipitates damage to the optic nerve which may lead to glaucoma.
The team surmises they have discovered a neural progenitor stem cell niche on the anterior region of the optic nerve. Moreover, this niche is depletable by age, proffering an explanation for age-related glaucoma. For the future, the researchers state they now plan to use genetically modified mice to investigate whether the loss or malfunction of these stem cells cause glaucoma.
Source: University of Maryland School of Medicine
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