Objective: To understand basic methods of assessing usable vision for learning

• Functional vision assessment (FVA) is conducted by a teacher to ascertain how a child is using vision to indicate the best format for educational materials or how to modify them.
• FVA begins with observation of the eyes to look for abnormalities, discharge, or muscle imbalances. How the pupils respond to light shows whether the eyes control the amount of light coming into the system. The pupils should diminish in size when a light is directed at them and enlarge when the light is removed. Observing the position of a light directed at the bridge of the nose as it is reflected in both pupils may indicate a muscle imbalance, if the reflection falls on different points of the pupil.
• Muscle balance also indicates whether the eyes are working together. Check this with a cover test, drawing the child’s attention to a light or object presented centrally and simultaneously covering one eye with a hand or piece of paper. While attention and focus is still on the central stimulus, remove the cover and see if the uncovered eye moves (usually toward the object). Repeat with the other eye covered. Movement of either eye after uncovering indicates that the eyes are not working together, that the eye that moves is compromised in some way, or that the moving eye is not functioning properly. If the child resists having an eye covered, that indicates that it might be functioning as the better eye.
• Normal visual field is 180 degrees temporally and 110 degrees vertically. Check the child’s visual pursuit by moving a light or object horizontally, vertically, obliquely, and circularly. Observe the child’s ability to attend to and follow the stimulus, and note any lags in movement or loss of attention. This information should be placed in the context of other findings on muscle balance and visual field. It can confirm or challenge your previous observations.
• Conducting an FVA is limited only by your imagination. Check how far away you can stand from the child and still hold her attention, or note whether she can avoid objects in the lower field when walking, or whether she bumps into tree branches overhead. If the child reads print, bring examples of different print sizes and fonts to find the most comfortable size, determined by reading speed and the distance she holds the print from her eyes.
• More information on functional vision assessment is available from Low Vision Online.