Convergence insufficiency: What causes it?

Convergence insufficiency occurs when your eyes don't turn inward properly when you focus on a nearby object. When you read or look at a nearby object, your eyes should turn inward while you focus, so you can see a single image. But if you have convergence insufficiency, you need to use extra effort to move your eyes inward for focusing. This extra effort results in various symptoms, including eyestrain.

This condition is most frequently diagnosed in adolescence. Some parents of children with convergence insufficiency may think their child has a learning disability because of this condition. However, learning disabilities aren't usually caused by convergence insufficiency. If you think your child may have convergence insufficiency, look for some of its signs and symptoms:

• Eyestrain
• Headaches
• Difficulty concentrating
• Squinting, rubbing, or closing one eye
• Blurred vision
• Difficulty reading (words seem to float on the page)
• Double vision

Your child's doctor or eye doctor will need to do a special eye-focusing test to see if your child has convergence insufficiency, since it may not be detected in a brief annual eye exam. Convergence insufficiency is sometimes treated with eye-focusing exercises, although your child's doctor may prescribe special glasses in some instances. Surgery is often a last resort.

Doctors at Mayo Clinic and across the country are currently participating in a study to determine if different eye-focusing exercises can effectively treat convergence insufficiency in children ages 9 to 17. The study is sponsored by the National Eye Institute of the National Institutes of Health.