In order to function properly, the eyes must be able to focus, coordinate, move and assess their surroundings. These are basic visual skills. However, some people have difficulty with one or more, leading to visual complications. Some signs you or your loved ones have a basic visual dysfunction may include difficulty reading or with reading comprehension, headaches, eye pain and/or fatigue, double vision, poor performance of tasks, difficulty with rhythm, challenges with learning left and right, and reversing numbers or letters when copying or writing.  The following articles go into more details on the attributes and impact of each basic visual skill.