What is visual acuity and contrast sensitivity and how will they be measured?
Visual acuity refers to clarity or sharpness of central vision, rather then the extent or clarity of peripheral vision. Most people who are familiar with going to the eye doctor, have acuity measured using the Snellen Eye Chart, which is made up of rows of letters, numbers or other symbols that become progressively smaller. At our Visual Function Service, a variety of specialized methods, such as visual acuity cards and preferential looking methods, are used to measure acuity. These methods are also adapted for age, developmental level and visual impairment and are complemented by electroretinogram and visually evoked potential as needed. In addition, we measure contrast sensitivity, which is the ability to see objects that have low contrast features or contrast poorly with other objects or a background. When possible low contrast detection is assessed using simple schematic faces and symbols or letters. Contrast sensitivity testing is important because in some conditions, it is much m
