Patricia Gill woke up one morning seven years ago, opened her eyes and realized something was very wrong.
"I had a black cloud over my left eye," said Ms. Gill, a former real estate agent and interior designer who took up landscape painting after retiring. "I could see through it, but it was like a black cloud there."
It took a while for doctors to determine the cause, but when she heard the diagnosis, Ms. Gill couldn't believe her ears: age-related macular degeneration, or AMD.
"And I thought, 'Holy God, I'm not old.' I was shocked." She was 58.
The prospect of losing her vision and her independence left the Burlington, Ont., woman reeling and depressed, a common reaction among those diagnosed with AMD.
"I stopped painting and I started renting those tapes where they tell stories, talking books. And half of them you can't hear and I thought I was going deaf, too.
"I'm lying in bed crying, saying, 'Oh my God, why is this happening to me?' "
About one-third of Canadians aged 55 to 74 and 40 per cent of those 75 and older have some form of AMD. But its slow, painless progression means many don't realize they have the disease until it's detected during an eye exam or the condition reaches an advanced stage.
Those with a family history of AMD, a fair complexion and light-coloured eyes are most prone to the condition. But tobacco use is also a major culprit, multiplying a person's risk of developing AMD by up to six times that of non-smokers, studies show.
Experts say the incidence of macular degeneration -- which affects more than two million Canadians and is the country's leading cause of vision loss -- is set to explode as the population ages.
The disease affects the macula, an area at the centre of the retina in the back of the eye that is responsible for fine-focused visual tasks such as reading, driving, telling time and recognizing faces.
Most people -- 85 to 90 per cent -- develop the dry form of macular degeneration, which starts with a failure of the deepest layer of pigmented cells in the retina to clean up byproducts produced by nearby cell layers.
"And so we see little yellow deposits (called drusen), which is the garbage that's been left and not cleaned up," said Pat Harvey, an ophthalmologist at Toronto Western Hospital. "That's the very beginning of the dry form.
"Patients complain about not being able to see fine things as well," she said. "They need more light to read and they can't see small print as well."
Symptoms may also include an inability to differentiate between navy blue and black, as the disease progresses and the cells in the macula begin to lose their pigment.
With the most serious and aggressive form of macular degeneration -- called wet -- the cell layer "gets so sick that it actually cracks and blood vessels underneath grow up through the cell layer," Dr. Harvey said.
"I tell patients it's just like weeds growing up through the cracks in the patio," she said, explaining that these blood vessels, which are leaky by nature, begin to ooze fluid.
"Instead of having a tight layer of cells that's holding all the fluid back, you now have a puddle form and that lifts the other . . . layers like a blister right in the very centre.
"The patients then get a dark spot in the centre with distortion of the vision," she said, noting that patients complain of straight lines turned wavy and a washing out of colour.
"And that spot gets bigger and bigger as the puddle gets bigger and as the blood vessel grows."
What results is a blackened- or greyed hole in the straight-ahead line of sight, surrounded by clear images around the periphery, sort of like a visual doughnut.
While there is no treatment for dry macular degeneration, a diet rich in leafy green and yellow-orange vegetables and fruits, as well as supplements containing antioxidants such as lutein and zeaxanthin, have been shown to slow the progression of the disease.
These micronutrients protect retinal cells and blood vessel membranes from oxidative damage, said Joanna Seddon, director of the epidemiology unit at the Massachusetts Eye and Ear Infirmary, part of Harvard's School of Medicine.
"I think prevention is really very important," Dr. Seddon said from Boston. "That way, we would have less of a burden of the advanced form of the disease . . . preventing it from beginning and preventing it from moving to the more damaging stages."
That's because in some cases, dry AMD can spontaneously develop into wet AMD, which accounts for 10 to 15 per cent of all cases and 90 per cent of severe vision loss associated with the disease.
For those with wet AMD, there is some light at the end of the tunnel, however.
A treatment called Visudyne, approved for use in 2000, has been found to arrest the disease for many patients and in some cases has even slightly improved their vision.
Visudyne is a light-sensitive drug injected into the bloodstream that travels to the abnormal blood vessels in the eye. A cool laser shone into the eye activates the drug, sealing up the leaky vessels.
Ms. Gill, who has wet macular degeneration in her left eye, had three treatments in 2001 before her AMD stabilized. She recently had another and it's likely she will continue to need more as time goes on.
But the therapy isn't cheap -- about $2,500 a shot -- and not all provincial health insurance plans cover the cost.
Other drugs are being developed: one called Lucentis is still being tested, but preliminary results suggest the drug may be an added weapon in doctors' arsenals against the disease. Avastin, a drug for colorectal cancer that's being used experimentally for wet AMD, also shows promise.
Ms. Gill, now 67, considers herself lucky that Visudyne came along when it did.
Her sight is far from perfect in her left eye -- and she has the beginnings of dry AMD in her right -- but her vision loss seems to have stabilized. She is painting again, although her once highly detailed canvases have given way to softer, less intricate scenes.
"I just hope I can continue the way I am without it getting any worse," she mused. "And I really hope my good eye will be spared."