Convergence Insufficiency is when slightly misaligned eye muscles pull and struggle to correct. This results in a buildup of eyestrain making it hard to concentrate. Continued this can cause a sleepy feeling while reading, headaches, classical or eye migraines and attention problems. Some people cannot see 3-D pictures or movies. This is a very common yet very much under- diagnosed problem. Except for the 3-D perception it can easily be correct for with prescription prism reading glasses.