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Glaucoma: the strong, silent type

Dr. Sivak holding eyeball
In his lab at the Krembil Research Institute, vision scientist Dr. Jeremy Sivak is searching for clues about what causes Glaucoma, a disease that often leads to blindness, and strategies for preventing and repairing the degeneration that causes it. (Photo: UHN)

Glaucoma is one of the most common eye diseases, but most patients won't know they have it until it's too late.

That's because the eye disease silently stalks it's victims over several years. It may cause no pain, but gradually wears down a person's vision by damaging the optic nerve, a vital link responsible for sending what you see to your brain.

Of the estimated 400,000 Canadians who live with glaucoma, most will first notice a loss of peripheral vision followed eventually by a disintegration of their central vision. The effects are irreversible and often lead to blindness.

"It's an incredibly common and serious problem because it has no direct treatment that addresses what is pathologically taking place," says Dr. Jeremy Sivak, a scientist at the Krembil Research Institute's Donald K. Johnson Eye Institute at UHN.

Dr. Sivak, who investigates, among other things, the mechanisms that underpin glaucoma as well as methods for drug delivery in the eye, sat down with UHN News recently to discuss the search for answers about the disease ahead of World Glaucoma Week, which wraps up on March 18.

QUICK FACTS ABOUT GLAUCOMA

  • 5000: number of patients the Glaucoma Clinic at UHN treats each year
  • No. 1: glaucoma is the leading cause of irreversible blindness in the world
  • 400,000: estimated number of Canadians who have glaucoma
  • 10: percentage of elderly Canadians estimated to have glaucoma
  • There is no cure for glaucoma​

Question: What is glaucoma?

Dr. Sivak: All of our visual perception of the world is acquired through our eyes. All of that information that the eye collects is sent through the optic nerve at the back of the eye. The nerve is really just a fine thread that is very vulnerable. It's actually quite long and is part of the central nervous system and our brain. Glaucoma really is the degeneration of the nerve at that pinch point where it exits the eye, and the neuron cells that form it.

Q: What have we learned from recent research in this area?

A: We've learned that glaucoma is essentially a neurodegenerative disease and there is a lot of research looking into parallels between glaucoma and other neurodegenerative diseases, such as Alzheimer's disease. Glaucoma is similarly a slow, chronic, irreversible process which is associated with aging.

Q: What are the risk factors for it?

A: There are a wide variety of risk factors associated with glaucoma. Increased intraocular pressure (pressure inside the eye) is the most prominent, but many of the risk factors for other neurodegenerative diseases are the same. The biggest one is age. Smoking, vascular disorders, low or high blood pressure – anything that upsets the normal metabolic balance in this very delicate tissue – also contribute to the cause.

Q: Where do you see your research going in the future?

A: Methods to reduce eye pressure are partially effective, and have become very refined.  The direction we need to go is toward neuroprotection; towards directly treating the degenerative cascade and protecting those neurons that are dying, prior to the degeneration - interrupting that process and then toward developing regenerative therapies.

Q: What is your approach in the lab?

A: As far as understanding glaucoma, we are behind some of the other neurodegenerative diseases in that we don't have a smoking gun. There are all these risk factors, but we are still looking for the central cause of the optic nerve degeneration. No matter which combination of risk factors, the disease proceeds in a similar way. Something is happening at that site in the retina, in that thin string coming out the back of the eye. My lab is trying to better understand what that injury is, and find ways to prevent and repair it.​

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