Vision therapy effectively treats convergence insufficiency

Issue: June 2012

ByAndrea Keele, OD

To the Editor:

In reference to the article “Understanding proprioception may be the key to treating visual fatigue” (March 2012, page 14), I find it absolutely appalling that nowhere in the article was vision therapy ever mentioned for the treatment of convergence insufficiency. Glasses with prismatic correction may reduce the symptoms but do not treat the underlying condition. Many patients benefit from the prism initially, but the effect tends to wear off as time goes on.

In the Convergence Insufficiency Treatment Trial, results found that vision therapy was by far the most effective treatment for convergence insufficiency. I am a behavioral optometrist who treats children every day with learning-related vision disorders and I see the results. I do recommend glasses with prism to help the child until he or she can develop the proper eye skills with vision therapy, but they will not be any better off in the long run. Please draw attention to this treatment option and reference the Convergence Insufficiency Treatment Trial.

Reference:

Convergence Insufficiency Treatment Trial Study Group. Randomized clinical trial of treatments for symptomatic convergence insufficiency in children. Arch Ophthalmol. 2008;126(10):1336-1349.

Andrea Keele, OD

Insight Eyecare Specialties

Kansas City, Mo.

Dr. Krall responds:

Thank you for drawing attention to the use of vision therapy for resolving convergence insufficiency. Grisham reviewed the literature and found vision therapy to be an effective cure 93% of the time.

I believe vision therapy is an effective treatment for adults and especially children who suffer from convergence insufficiency. It has also been documented that vision therapy is effective in treating learning-related visual disorders in children. However, for those patients who are unable to avail themselves to this treatment (because of time or financial restraints), prism has served as an alternate form of management.

The Illinois College of Optometry (ICO) convergence insufficiency treatment study evaluating the effectiveness of prism in presbyopes conducted by Dr. Bruce Teitelbaum and Dr. Yi Pang brought attention to several interesting facts. First of all, there was no correlation with the amount of exophoria or near point of convergence and the magnitude of patient’s symptoms. Many patients, by definition, with convergence insufficiency are asymptomatic. On the flip side, many patients who did not have convergence insufficiency, by definition, were extremely symptomatic.

A follow-up on the patients involved in the ICO study nearly 5 years out found that nearly all of these patients were asymptomatic with little, if any, change in the prism that had been prescribed.

Our proprioceptive system is responsible for providing subconscious feedback to our visual system regarding where an object (e.g., words in a book or images on a computer screen) is in space. Is it possible we have been looking under the wrong rock to uncover the mechanisms causing our patients’ asthenopia?

Reference:

Grisham JD, Bowman MC, Owyang LA, Chan CL. Vergence orthoptics: validity and persistence of the training effect. Optom Vis Sci. 1991;68:441-451.
Teitelbaum B, Pang Y, Krall J. Effectiveness of base-in prism for presbyopes with convergence insufficiency. Optom Vis Sci. 2009;86(2):153-156.

Jeffrey P. Krall, OD

Krall Eye Clinic

Mitchell, S.D.