Do you remember when we discussed convergence insufficiency? Well, convergence excess is similar in that the eyes have difficulty working together at near. The difference is that in convergence insufficiency, the eyes are not converging, or “crossing”, enough to look at the intended target, whereas in convergence excess, the eyes are converging too much, or “working too hard”, to look at the intended target. In order for us to be able to complete near-related tasks (such as reading or writing) comfortably, our needs need to find the right balance to converge just enough for what we are intending to look at.
The symptoms of convergence excess are similar to that of convergence insufficiency.
- Eyestrain, eye fatigue, and/or headaches with near tasks
- Double or blurred vision at near
- Words moving, jumping, swimming, or floating when reading
- Frequent loss of place when reading
- Difficulty concentrating or reduced attention with near tasks
- Difficulty remembering what was read
- Covering or closing an eye when reading
- Avoidance of reading or other near related tasks
- Poor judgement of distances
- Difficulty catching balls or other objects thrown in the air
- Clumsiness (ie tripping on uneven surfaces, stairs, curbs, etc; bumping into objects)
Our visual system is quite complex and includes vergence (“eye-teaming”) ability, accommodation (“eye-focusing”) ability, saccadic or pursuit (“eye-tracking”) ability, and peripheral awareness. Our visual system also provides information to and gets information from other systems, such as our vestibular system and musculoskeletal systems, to aid in how we function.
Specialized tests are required to assess the visual system in detail and diagnose difficulties the visual system may be facing after a concussion, including convergence excess. These tests are not usually completed during a standard eye exam, and therefore these difficulties are often overlooked.
Our specialists are trained to complete these specialized tests. These tests include:
- Eye alignment
- Eye-teaming ability, stamina, and flexibility
- Focusing ability, stamina, and flexibility
- Scanning and tracking ability and stamina
- Gaze stability
- Assessment of peripheral awareness
- Visual-spatial function
- Assessment of abnormal egocentric localization
- Visual-vestibular function
- Visual-verbal automaticity
- Visual processing skills
For more information on the disorders of the visual system following brain injury, please read our Behavioural Optometry, Post-concussion Vision Syndrome, and VVM articles.
Glasses containing prism lenses may be prescribed to reduce the symptoms associated with convergence excess. It is important to note that although prism glasses can relieve symptoms, they are not a “cure”.
Studies show that vision therapy is the best treatment for convergence excess and other concussion-related vision problems. Vision therapy is an individualized treatment program, where “eye exercises” (‘brain exercises in improving control of the eyes’ would be more accurate) are used to retrain the visual system to work accurately and efficiently. As the patient makes improvements, exercises are adjusted to encourage further visual improvements over time.
Last update: January 2019