Convergence insufficiency is a condition in which the two eyes have cannot turn in (converge) towards each other when looking up close, meaning the two eyes struggle to send a comfortable, single image to the brain.
This can cause the brain difficulties when trying to process visual information (making sense of what is seen), leading to learning difficulties. Convergence insufficiency is not an eyesight problem and may be unrelated to short- or long-sightedness. So even though a person can see clearly, the brain still struggles to process the image. Those with convergence insufficiency will have issues sustaining near visual function. Convergence insufficiency problems generally cannot be improved with glasses or surgery.
A person will often compensate for convergence insufficiency, resulting in
1. The eye muscles working harder to pull the eyes together to maintain convergence or
2. The brain only selectively using one eye to focus up close; the other being ignored relaxes and turns out (either by a small, subtle degree or a much larger, more noticeable degree).
Studies show 58% of children with suspected or diagnosed learning or behavioural difficulties/disabilities have convergence insufficiency.
Those with convergence insufficiency may experience
- Short attention span
- Avoidance of near tasks
- Eye strain (asthenopia)
- Difficulty in changing focus from distance to near
- Blurred or double vision (if the brain is using only one eye, this won't be noticed)
- Difficulty concentrating on near distance work
- Perception of print moving, wobbling or shaking when reading
- Oculomotor dysfunction; eye tracking and fine motor movement difficulties
- Squinting or closing one eye