Canadians have long had difficulty in seeing what a serious disease is diabetes.

So serious, it turns out, that some people with diabetes can't see anything at all. Along with increasing the likelihood of heart disease up to six times and being a significant culprit in renal failure, diabetes is the leading cause of adult blindness in Canada.

As with the other complications, ranging from loss of lower limbs to erectile dysfunction, the destructive effect of diabetes on the vision relates to its destructive effects on the relevant blood vessels.

Without this disease, Deborah Wilson would be considerably less busy. And she wouldn't object to that at all.

"I would say that something like 50 per cent of my patients have diabetes," remarks Wilson, a longtime ophthalmology technician currently creating a new practice at the Durham Regional Vision Centre in Whitby, Ont.

"Diabetic retinopathy can cause vision loss in refractive changes, vitreous hemorrhage, central vision loss in macular edema and peripheral loss through retinal damage," she explains. "Diabetics are also at greater risk to develop other eye diseases, including cataract and glaucoma."

Vision loss, one of the most disturbing impairments in the minds of those who are healthy, is a dramatic caution on the need for the general population to prevent diabetes through the maintenance of physical fitness, or to manage an existing diabetes condition with fastidious control of blood glucose levels.

People are familiar with the notion of 20/20 eyesight as being perfectly healthy vision, meaning a person sees clearly at 20 feet what a normal eye should see at that distance. Low vision within the category of functional vision is 20/70, or needing to be at 20 feet distance to see clearly something that should be well visible at 70 feet, while legal blindness is rated at 20/200.

Yet up to the point of profound vision loss at 10/500 and beyond, however, there are things that can be done for patients -- and that's where ophthalmologists and such associate technicians as Wilson come in.

"My position is to assess and recommend the correct visual aid for clients and to assist them to learn how to use their visual aids to help them with their reading and writing skills," says Wilson, who has been an ophthalmic technician for 23 years, almost as long as the specialty has been properly established. "The progression of the disease affects ongoing treatment that influences the prescription of visual aids."

While vision loss is one of the grave potential consequences of diabetes, Wilson says an increasingly sophisticated array of technical devices have made more functionality possible for such patients.

"In the past decade, the advances in new computer technology have closed the gap for people who are visually impaired to become fully independent at work, school and at home in reading and writing skills," she remarks. "Much of this technology comes in the form of hardware and software. The standard PC has become a tool for creating accessibility to low vision and blind persons."

Some related tools:

Closed circuit television magnifies print and pictures, including images of such objects as insulin syringes, allowing low-vision people with diabetes to read the information and prepare self-administered injections. This tool can also be used in combination with hand-held magnifiers.

Scanners are used in conjunction with specialized software that can recognize print and read it aloud to the low-vision listener.

Other computer software enlarges print and can also read it back to the user, while complete screen readers will pronounce on everything that's on the monitor.

Global positioning software is being adapted for the laptop computer of the blind traveller, allowing access to street information, points of interest, university campuses and more. "There is no universal device for diabetic low vision," notes Wilson, "and this is why [these patients] must be assessed and trained by a low vision specialist and monitored as their vision changes for new aids and devices."