Apparently, there are a bunch of medicines that don't play well with vision problems.
Some of the anti-psychotic medicines affect accommodation, produce blurred or double vision or impact the visual field include: Zoloft, Risperidal, Wellbutrin, Paxil, Citalopram. Even though this article doesn't point out Xanax or other benzodiazepans as being problematic, they have come up on other lists. Since a lot of folks with strabismus often suffer from anxiety, depression, or social anxiety and are prescribed these medications, they may be worsening some of the problems they are working so hard in vision therapy to correct.
Other medications impacting vision include antihistamines including Zyrtec, and a number of hypertensives.