In Brief
Convergence Insufficiency (CI) is an eye teaming disorder characterized by a diminished ability to bring both eyes inward evenly to view a target held at close range.
Behind the Scenes of CI
Convergence insufficiency is one of many binocular vision disorders. As with most of these disorders, there is a range of severity. Some amount of function is likely present, however minimal. Only with extra conscious effort can the individual achieve a level of performance above what the disabled visual system is able to produce automatically. This expenditure of effort is costly and results in headache, eyestrain, double vision and overall fatigue during prolonged periods of demand. It is important to consider a few things at this point. First, consider of the level of demand in an academic setting. A student’s typical work day centers around visual distances within arms reach. Second, if extra effort and attention is necessary to physically meet the visual demand, it must be diverted from other cognitive processes. It becomes very difficult to accomplish all the necessary cognitive steps involved in the process of reading and learning, when such a large portion of the total effort and attention must be allocated to a poorly functioning visual system. Third, how long can the individual be expected to maintain this level of effort? This depends on the level of demand. How much does the visual system have to give or how much automatic/natural function does the system have vs. how demanding is the visual task. Over time, the individual learns to estimate the effort required upon inspection of the visual task. A decision is then made as to if the activity is worthy of the effort. Some may decide to push through and suffer the likelihood of symptoms later, while others may refuse or avoid the task all together. The end in no way justifies the means. Some have more desire to push through to completion knowing the costs involved while others view the same costs as too great making a half hearted attempt or purely guess their way through. Why would anyone want to willingly put themselves through something that they know will produce mediocre to undesirable results? Lastly, consider that this individual is usually unaware that their way of visual function is atypical. This is the only way they’ve ever known and do not realize they are at a physical disadvantage as compared to their peers.
How is CI diagnosed?
Your optometrist may be able to detect poor convergence ability during a comprehensive eye exam. However, CI isn’t always easily noticeable. A specially trained optometrist known as a developmental optometrist looks specifically for inconsistencies in the binocular functioning of the visual system. Due to the fluctuating nature of demand on the visual system, CI is more easily diagnosed during an eye exam scheduled later in the day when fatigue is likely greater. Convergence ability should remain constant independent of fatigue in a fully functioning binocular vision system. In addition to reduced convergence ability, other observations include the need to hold their breath or tensing up during convergence tasks. Patients will admit to having to put forth effort, “Well if I try, I can do it longer.” Efficient visual systems do not require conscious effort to perform. Ongoing symptoms including the ones mentioned earlier like squinting or covering one eye, poor reading skills but very smart, poor coordination, often disorganized, and easily losing interest in printed desk work increase the likelihood that a binocular vision disorder is present.
Can CI be treated?
Yes, absolutely. CI will not resolve on its own and is best treated with in office vision therapy according to recent studies. Your optometrist can make a referral to a developmental optometrist who offers in office therapy in your area. A list of board certified developmental optometrists can be found at covd.org.
Questions?
If you are questioning CI for yourself or a loved one, speak with your eye doctor about specialized vision testing. It is important to rule out a treatable vision disorder.
Scheiman, M. et. al., A Randomized Clinical Trial of Treatments for Convergence Insufficiency in Children, Arch Ophthalmol. 2005;123:14-24.