“The big challenge in Canada is that we have an aging population, and all the major diseases that cause vision loss are associated with aging,” says Dr. Keith Gordon, Vice President of Research at the Canadian National Institute for the Blind. “We’re outliving our eyes.”

The big three

When it comes to age-related vision diseases, the two major ones are diabetic macular edema (DME) and age-related macular degeneration (AMD), with retinal vein occlusion (RVO) being the less significant third. DME is a condition that causes damage to the retina due to diabetes, and is a consequence of diabetic retinopathy which is the leading cause of blindness in people aged 20 to 64. AMD comes in two forms: the more common dry variant and the less common, but more severe, wet variant. In both types, deposits in the back of the eye weaken the layer under the retina, allowing blood vessels to grow through. Retinal vein occlusion is a blockage in the veins that drain blood from the eye, and can result in rapid and complete vision loss.

These three conditions have a variety of different profiles and risk factors, both controllable (diet and smoking, for example) and uncontrollable (like genetics). Three things that these conditions all have in common, however, are that the risk of developing them increases with age, they currently have no cure, and they have a similar metabolic mechanism. “The three diseases are all driven metabolically by the formation in the eye of unusual levels of a hormone known as vascular endothelial growth factor (VEGF),” explains Dr. Netan Choudhry who is the medical director of the Vitreous Retina Macula Specialists of Toronto.

 

Good treatment options, but no cure

Within the last two decades, the arrival of a number of anti-VEGF therapies on the market has revolutionized the treatment of these diseases, often allowing doctors to completely preserve eyesight in cases where blindness would have been previously inevitable. “The treatments are miraculously successful,” says Dr. Alan Berger, a vitreoretinal surgeon at St. Michael’s Hospital. “But it’s important to remember that they are a treatment, not a cure.”

Injection of anti-VEGF therapies needs to continue on an ongoing basis for treatment to be successful, and the outcome can vary dramatically depending on how early the disease is caught. “We wish we had a cure or a good preventive treatment for these diseases, and one day we may have it,” says Dr. Berger. “Right now, though, early diagnosis is the best chance for a good outcome.”

Early symptoms of these eye diseases can include blurry or distorted vision, dark spots in central vision, or sudden loss of vision. pain in the eye. In some cases, however, the diseases can progress quite severely before any symptoms are noticed. “We have two eyes, and in a situation where one eye is losing vision, the other eye takes over to an extent, so the vision loss creeps up on most people,” says Dr. Choudhry. “One of the best things patients can do is to see an eye care provider for a dilated eye exam once a year, starting at the age of 45.” Since there are therapies available for these conditions, there is no reason why anyone should go blind provided they have solid education on these diseases-period.

Catching these diseases early, before they have progressed, not only results in better prognosis with current treatment options, but can also preserve vision in a way that may leave the door open should a cure be developed in the future. “There is an incredible amount of work going on right now that is very promising,” says Dr. Gordon. “But we’ll have to wait at least a few years.”