Convergence Insufficiency is a binocular vision problem, in particular the eyes’ ability to “go cross-eyed” in a precise and controlled manner. Binocular vision is the ability of our eyes to co-ordinate movement, for the brain to simultaneously perceive two unique images and form one 3D-image as a result.
When we are performing tasks, such as reading or catching a ball, the binocular vision system is put to its maximum effect. In reading, the eyes must work precisely in sync with each other as we perform multiple rapid saccades (eye flicks) and at the same time the eyes must also converge (point slightly inwards to each other) and maintain the angle of convergence as they flick across the words. Some people erroneously refer to this movement as tracking, which it is not in the truest sense of the word.
The prevalence of convergence weakness problems (of which convergence insufficiency is one) is approximately 12%. The root causes are either neurological (brain based) or muscular in nature.
When reading, convergence weaknesses often present with headaches, brow-ache, tiredness, periods of double vision, words jiggling on the page or blur. The condition is associated with poor concentration when reading or performing similar near vision tasks and also critically with a reduction in reading ability.
These problems can usually be resolved therapeutically with targeted, scientifically validated, eye exercises, called orthoptics. These exercises are designed to train both the muscular ability of the eyes in a convergent position but also to train the brain’s ability in stereoscopic (3D) perception. Other treatment modalities include spectacles or a combination of spectacles and eye exercises.