The Effect of Fresnel Prism Treatment in Consecutive Esotropia

ABSTRACT

PURPOSES: To investigate the effect of Fresnel prism treatment in patients with consecutive esotropia after the surgery of exotropia. METHODS: Eighteen patients who have failed alternating occlusion therapy at least 1 month for consecutive esotropia without limitation of ocular motility following surgery for an exotropia were managed with Fresnel prism for esotropia associated with diplopia. The Fresnel prismatic power was selected to solve the diplopia and was changed in accordance with the degree of esodeviation during the follow up period. The surgical correction was performed in the case with increase of esodeviation in spite of the Fresnel prism therapy for 6 months or more. The angle of deviation and diplopia before and after the Fresnel prism therapy were investigated. RESULTS: The mean age at surgery for an exotropia was 7.8 years. The Fresnel prism therapy was performed at 4.2 months after exotropia surgery to solve esotropia in average 15.4 prism diopters (PD) at distance and 14.8PD at near. Of the 18 patients 11 (61.1%) had a successful outcome after average 14.8 months, i.e. 8PD or less of esodeviation, with relief of diplopia without the Fresnel prism. Two patients used the Fresnel prism to solve diplopia associated with esodeviation of 8PD or less. Five patients had esodeviation with 10PD or more and 2 of them were eventually needed a operation for esotropia. CONCLUSIONS: The Fresnel prism treatment is an effective device in treating diplopia as well as decreasing the frequency of surgery for esotropia in consecutive esotropia with diplopia.