There’s a nice paper I cited yesterday regarding CI, and today I’d like to point out another set of data that helps address a question frequently asked of us by patients, or at least a question they wonder about. How stable will my condition be over the course of time? While this paper doesn’t provide an easy answer to that difficult question, it does give some insights regarding adult-onset convergence insufficiency. The CITT has focused a spotlight on patients between 9 and 18 years of age, but comparatively little has been written on older patients. This article is a retrospective review of patients with CI who were at least 19 years of age.
The authors looked at the rate of increasing exodeviation in their CI population, and selected a progression of at least 7 prism diopters as significant. They refer to this as the Kaplan-Meier rate of progression. The rate of decompensation of 7 prism diopters or more was 4.2% at 5 years, 13.5% at 10 years, and 24.4% at 20 years after the diagnosis was made. This provides important data with which to counsel patients in projecting what is likely to happen over the course of time with interventions as prescribed by ophthalmologists.
Another set of data worth noting is that the high majority of patients in this population were managed conservatively with prism, and without the need for surgery. Prism was successfully prescribed in 88% of the cases, and convergence exercises prescribed in 9% of the cases. The authors write that the low rate of exercises in part may be the result of difficulties encountered with elderly adults, or by the personal preference of treatment by the ophthalmologists.
Taken together, the results point toward consideration of prism and/or vision therapy to compensate for increasing CI in adulthood. It is possible that a more aggressive posture toward prescribing office-based vision therapy and gaining compliance would have significantly lessened the Kaplan-Meier rate of progression over time. Surgery was reserved for only a handful of cases after consideration of prism and convergence exercises, consistent with guidelines provided by von Noorden and Campos in their text on binocular vision.