Researchers at Ohio State University and Wright State University in Dayton, Ohio, recently discovered a new—albeit impractical—method for monitoring treatment efficacy for convergence insufficiency (CI): magnetic resonance imaging (MRI). They randomized seven adult patients with symptomatic CI to either 12 weeks of vergence-accommodative therapy or placebo therapy and asked them to perform vergence eye movements during baseline and post-therapy functional MRI scans.
At baseline, they found activation in the occipital lobe and areas of the brain devoted to attention. After therapy, MRI showed the activation in the occipital lobe decreased in spatial extent but increased in the level of activation (posterior and inferior portion of the occipital lobe). In addition, regions of the lingual gyrus were activated after vergence-accommodative therapy, but not placebo.
“Observed activation pre-therapy consistent with top-down processing suggests that convergence requires conscious effort in symptomatic CI,” the researchers conclude. “Decreased activation in these areas after vergence-accommodative therapy was associated with improvements in clinical signs such as fusional vergence after vergence-accommodative therapy.”
|Widmer DE, Oechslin TS, Limbachia C, et al. Post-therapy functional magnetic resonance imaging in adults with symptomatic convergence insufficiency. Optom Vis Sci. 2018;95(6):505-14.|