What is Convergence?
To see clearly and without confusion at close distances, both eyes must be aimed precisely at the object the person is trying to see.
Unfortunately, not everyone develops this ability in childhood. Inaccuracy of the alignment of the eyes convergence results in visual fatigue, blurred or doubled vision, poor judgment of depth, eye ache, headache and mental fatigue.
Convergence excess is a condition in which a child’s eyes have a tendency to aim closer than the object, which the child is trying to see. It is possible to achieve correct aim only by exerting extra effort (Figure 1). Prolonged periods of close work can cause considerable discomfort.
Many cases of convergence excess are due to long-sightedness. The need which longsighted people have to exert extra focusing (accommodation) to see clearly at close range has the effect of making the eyes tend to turn in too far, which creates the convergence excess.
Convergence excess affects about ten per cent of school children. It is less common in adults.
Convergence excess can be treated with the use of reading glasses (or bifocals), which relax the convergence and focusing systems, thus removing the need for extra effort.This often allows longer and more efficient concentration on close tasks. Eye exercises are not usually successful in treating convergence excess.
Convergence insufficiency is a condition in which the eyes have a tendency to aim further away than the object at which they are supposed to be pointed, Correct aim con be achieved only through extra effort (see Figure 2). Convergence insufficiency affects about five per cent of children and up to ten per cent of adults.
Convergence insufficiency is perhaps the simplest and most successfully treated eye coordination problem. Eye exercises are employed to train the eyes to aim efficiently without excessive effort.
Normal convergence is usually attained after three or four weeks of daily exercises.
Spectacles may be a useful aid to treatment; especially where there is also a focusing problem involved, although on their own they will rarely solve the problem.