esophoria esophoria esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. it is a type of heterophoria. esophoriaspecialtyophthalmology cause causes include: refractive errors divergence insufficiency convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies. unlike esotropia, fusion is possible and therefore diplopia is uncommon.