Prisms in the treatment of diplopia with strabismus of various etiologies

PURPOSE: We aimed to study the success of prism in regard to diplopia resolution score and associated factors in patients presenting with symptomatic diplopia arising from various etiologies. METHODS: In this descriptive, retrospective study diplopia resolution among 31 patients who were prescribed prism were analyzed. RESULTS: Fifty-four patients were evaluated for diplopia and 31 were included for the study done over 3 years. The mean follow-up was 15 months. Esotropia, exotropia, and hypertropia were seen in 39%, 51%, and 19.4% of patients, respectively. Furthermore, 71% received Fresnel prism and 29% were given ground glass prism. The mean prism power prescribed was 13.3 PD. 87% had complete resolution of diplopia; 96.8% continued usage of prism. High success rates were seen among patients with decompensated strabismus, sixth and fourth nerve palsy. Horizontal prism and oblique prism in the form of Fresnel prism yielded complete resolution of diplopia (P = 0.028). There was no association between the success of prism and etiology (P 0.058), history of trauma (P = 0.212), and type of deviation (P = 0.387). The study showed that oblique Fresnel prism can be considered for combined deviation. CONCLUSION: Our study showed prism to be effective in alleviating diplopia over a varied range of etiologies.