To evaluate the therapeutic results of the patients wearing the prism glasses due to strabismus with diplopia unrelated to strabismus surgery.

Between May 2002 and October 2016, this retrospective study evaluated medical records of 23 patients who were wearing prism glasses due to strabismus with diplopia unrelated to strabismus surgery. The patients failed to adjust to the prism glasses and stopped within 3 months were defined as the adaptation failure group. The patients wearing prism glasses for 3 months or more was defined as adaptation success group. In the prism adaptation success group, he patients who underwent strabismus surgery during follow up were defined as treatment failure. Data were collected the types and causes of strabismus, the deviation angle at starting treatment of prism glasses and last visits, best corrected visual acuity, Titmus stereo test and Worth 4 dot test.

Of the total 23 patients, 18 patients had horizontal strabismus, four patients had vertical strabismus and one had horizontal and vertical strabismus. The causes of strabismus were acute acquired comitant esotropia (12 patients), paralytic strabismus (9 patients), and thyroid associated ophthalmopathy (two patients). There was no significant changes in deviation angle as well as the prism diopter of prism glasses after prism glasses treatmet. The prism glasses-adaptation group was 70%, and 31% of them were performed strabismus surgery. There was no reduction in visual acuity in all patients. Among the prism glasses adaptation group, 33% of the prism glasses-adaptation group had poor binocular function.

In the strabismus patients with diplopia unrelated to strabismus surgery 70% of the patients adapted prism glasses more than 3 months and 31% of them required strabismus surgery. Therefore, prism glasses treatment may be one of the non-surgical approaches in the strabismus patients with diplopia unrelated to strabismus surgery.