Strabismus A misalignment of the eyes: the eye don't point at the same object together. Crossed eyes (esotropia) are one type of strabismus; "wall-eyes" (exotropia) are another. The exact cause is unknown, but appears to be a problem with the eye muscles. Strabismus can affect depth perception.
Presbyopia Condition in which the aging eye beginning at around age 40 is unable to focus at all distances, often noticed when print begins to blur. Additional symptoms include eyestrain, headaches, and squinting. Read our article about presbyopia.(08 February 2010 - Online article Boothe Eye Care )
