Although it's the most common procedure performed by eye health practitioners, the routine eye exam is anything but routine. An essential step in maintaining and restoring clear vision, a comprehensive eye examination determines much more than prescriptive eye wear. As well as assessing how your eyes work as a team, an eye exam can detect early signs of potentially blinding eye conditions like glaucoma and age-related macular degeneration (see box below). As well, it can reveal a number of other undetected health problems including high blood pressure and diabetes: diseases that can rob us of our sight.

Clearly it's a good thing to have periodic eye exams, but how frequently? The answer depends on a variety of factors including your age, your general health, the health of your eyes, the medications you take, your eyesight and your family history. As a further complication, it also depends on whom you ask, although there is general agreement that children should have an eye exam before beginning school. "Nova Scotia has one of the most robust procedures for this in the country," says Dr. Raymond LeBlanc, Vice President Research and Academic Affairs, Capital Health District.

Opinion is less consistent when it comes to the recommended frequency of eye exams for the rest of us. "The definition of 'regular' boils down to language and professional organizations," says Dr. LeBlanc. Guidelines compiled a year ago by the Canadian Ophthalmological Society (COS) suggest that there are not many changes in eye health between the ages of 19 and 40 and that healthy adults in this age range may only require an eye exam once every ten years. Between the ages of 41 and 55 the frequency is increased to once every 5 years; and from age 56 to 65 the recommended screening interval is every 3 years, changing to twice a year for healthy adults over 65

In contrast, the Canadian Association of Optometrists, like their American counterparts, takes the view that even if you have clear vision, only a complete eye exam can ensure that your eyes are healthy. Because many eye diseases can progress without symptoms or warnings, the Canadian Association of Optometrists recommends an eye exam once every one to two years for healthy adults between the ages of 20 and 64. They suggest more frequent visits for children and the elderly, and for those at high risk of developing eye problems or with certain medical conditions.

For the general public, the discrepancy in what constitutes 'regular' is confusing. "Optometrists recommend the eye exam at more frequent intervals" says Dr Alan Cruess, a professor in the department of Ophthalmology and Visual Sciences at Dalhousie University and District Chief for Capital Health, "but there's no big controversy around this." Cruess attributes the variation in recommended intervals for eye exams at least in part to the confusion between testing to detect eye disease and testing to address refractive errors. "The ophthalmologists and optometrists in this province have a strong working relationship," says Cluess. "We're working together with our family doctor colleagues to create a collaborative model of patient care."

In most provinces, public health insurance only covers certain groups for periodic eye examinations. Nova Scotia's provincial health plan, MSI, covers most services for those under ten or over sixty-five years of age. Coverage is limited to once every two years, with some exceptions based on medical necessity. MSI does not cover regular eye examinations for adults between the ages of 20 and 64, with the exception of those with specific health problems including diabetes, glaucoma and cataracts.

As a result, Nova Scotians between 20 and 64 whose costs are not covered by private insurance may avoid having an eye test unless they have vision problems. The 2007 Eye Health Report Card, a survey sponsored by the Canadian Association of Optometrists, found that only those who required corrective eyewear were likely to schedule regular eye exams. Yet unlike teeth, eyes don't usually ache when there is a problem and eyes that see clearly are not necessarily healthy. The guidelines suggested by optometrists may be in part a business model that capitalizes on funding allowed by the majority of third party insurance plans, but it's a model that makes sense when an eye exam catches a previously undetected problem.

The Three Thieves of Sight

1. Glaucoma ultimately causes blindness, yet because there are no symptoms of this disease until it is in an advanced stage, by some estimates at least half of the 250,000 Canadians with glaucoma are unaware that they have it. Incidence increases with age. Early diagnosis and treatment can slow the progression of the disease and prevent blindness.
2. Age-related macular degeneration can also occur without noticeable symptoms. A progressive condition that attacks central vision, AMD affects one million Canadians and is the leading cause of vision loss in adults over the age of 50. According to research conducted by the Canadian National Institute for the Blind, as Canada's population ages over the next 35 years, the incidence of AMD is expected to double. While there is no cure for AMD, early diagnosis enables more options for treatment to stabilize vision.
3. Diabetes blinds about 400 Canadians a year. Roughly half of the more than 1.5 million Canadians who have diabetes are undiagnosed. Because Diabetes can lead to glaucoma, cataracts and diabetic retinopathy (a weakening of the blood vessels that supply the retina), persons with diabetes  are advised to have annual eye exams. If diagnosed early enough, severe vision loss may be prevented or delayed.

Protect Yourself

• Wear protective goggles when exposed to dangerous chemicals, cleaners, tools and machines
• Wear protective lenses to shield your eyes from the sunWear protective eyewear when playing sports with a ball or puck
• Watch what you eat. According to Health Canada, a daily dose of the vitamins and minerals found in melons,  citrus fruit, carrots, spinach and kale can slow the progress of  age-related eye diseases. Research also shows that high consumption of the fats found in junk foods can boost the risk of developing AMD.
• Wear corrective eyewear that meets the legal requirements for driving. Poor eyesight is dangerous on the roads.

The Canadian Ophthalmological Society's Guidelines for Periodic Eye Examinations

(for healthy adults who do not notice anything wrong with their eyes or vision)

Screening Intervals for Low-risk Patients

• Age 19 to 40: at least every 10 years
• Age 41 to 55: at least every 5 years
• Age 56 to 65: at least every 3 years
• Over age 65: at least every 2 years

One exception to these guidelines is anyone experiencing symptoms like vision loss, changes in the field of vision, distortions to vision like haloes around lights and flashes or jagged lines. An eye doctor should assess these vision changes as soon as possible.

Additional exceptions to the guidelines include seniors and others who are at greater risk for developing eye diseases like Glaucoma and age-related macular degeneration (AMD), those who suffer from diabetes, those with a family history of eye disease, those with a previous eye injury, those taking certain medications and those with very poor eyesight. In these cases the Canadian Ophthalmological Society recommends more frequent screening (see guidelines below).

Screening Intervals in High-risk Patients

• Over age 40: at least every 3 years
• Over age 50: at least every 2 years
• Over age 60: at least once a year

Ophthalmologists are medical doctors who:

• specialize in eye and vision care
• diagnosis and treat eye disease
• provide comprehensive eye exams
• prescribe corrective lenses
  
• prescribe and administer medication
• perform surgery

Optometrists are non-medical practitioners who:

• assess the eye and the visual system
• assess ocular disorders and dysfunctions of the eye
• diagnose refractive disorders
• prescribe and dispense corrective and preventative devices

Opticians are non-medical practitioners who:

• supply, prepare and dispense optical appliances
• interpret prescriptions prepared by ophthalmologists and optometrists
• fit, adjust and adapt optical appliances