Eye Focusing, Coordination, and Tracking Problems
Below are vision-related problems whose symptoms often manifest in the classroom. A thorough eye exam is necessary for detection and treatment.
Accommodative Dysfunction is an eye-focusing problem unrelated to aging changes in the lens of the eye. The lens in each eye is unable to "accommodate" or change focus sufficiently to provide clear vision at all distances. This can occur in children as well as adults. In most cases, it is not that a child lacks sufficient focusing power, but rather he or she can't maintain and use his or her eyes’ focusing ability effectively. Eye focusing problems often occur after continued viewing of near objects like a book or computer screen. Children with accommodative dysfunction may experience symptoms like eye-strain, temporarily blurred vision and/or headaches.Amblyopia, commonly referred to as a “lazy eye”, occurs when one eye is not fully developed, resulting in blurred vision. Refusing to recognize both eyes as a team, the brain favors one eye while giving up on the other. The amblyopic eye is "turned off" or suppressed, hindering development of clear vision in that eye. Refractive Amblyopia begins early in life and is caused when one eye is more nearsighted or farsighted than the other. This makes it difficult for the eyes to focus together, resulting in suppression of the blurry eye. Strabismus (see Eye Alignment Challenges) is another common cause of amblyopia.
Convergence Excess is an eye coordination problem in which the eyes have a tendency to drift excessively inward. One must exert effort to pull the eyes outward, which can cause symptoms shared with convergence insufficiency (see below) including: eyestrain, headaches, blurred vision, double vision, sleepiness and (if reading) trouble remembering what was read.
Convergence Insufficiency is an eye coordination problem in which the eyes have a tendency to drift outward when reading or doing close work. This lack of “eye teaming” makes it difficult to use both eyes together without having to exert extra effort to maintain proper eye alignment, making it harder to work comfortably on up close tasks like reading and writing. Signs of eye teaming problems include headaches, blurred or double vision, difficulty concentrating, a short attention span, and closing or covering one eye while reading.
Occulomotor Dysfunction, also called an eye tracking problem, is an inability to aim eyes accurately. Children with eye tracking problems are unable to effectively control their eye movements. Aiming the eyes involves three different visual skills:
Fixations - the ability to maintain gaze on a stationary object such as a street sign or a picture in a book.
Pursuits - the ability to follow a moving object, like a thrown ball, with the eyes.
Saccades - the ability to accurately and rapidly shift a gaze from one point to another (such as from one word on a page to the next).
Eye tracking skills are particularly important for reading. Children lacking these skills may use a finger to follow along a line of print because their eyes can't. They may also skip or transpose words or frequently lose their place when reading.