The Canadian Association of Optometrists recommends the following schedule for those at low risk:

Infants and Toddlers (Birth to 24 months): Infants and toddlers should undergo their first eye examination between the ages of 6 and 9 months.
Preschool Children (2 to 5 years): Preschool children should undergo at least one eye examination between the ages of 2 and 5 years.
School Age Children (6 to 19 years): School children aged 6 to 19 years should undergo an eye examination annually.
Adults (20 to 39 years): Adults aged 20 to 39 years should undergo an eye examination every 2 to 3 years.
Adults (40 to 64 years): Adults aged 40 to 64 years should undergo an eye examination every 2 years.
Adults (65 years or older): Adults aged 65 years or older should undergo an eye examination annually.

*  Please note that these are minimum recommendations for those with no history of eye disease. Your optometrist may recommend a more frequent examination schedule if you have signs of active disease or are at higher risk of changes.