Visual Field Relocation and Clinical Effect of Fresnel Prism in Patients with Homonymous Hemianopsia

ABSTRACT

PURPOSE: To report the result of Fresnel prism application and adaptation for visual field relocation and functional vision improvement in homonymous hemianopsia patients. METHODS: Fifteen homonymous hemianopsia patients were prescribed Fresnel prism. To expand the visual field, Fresnel prism was placed base-out toward the defective field and patients were given an adaptation period of 1 month. The effects of the prism on field expansion was evaluated using Goldmann perimetry. In addition, the NEI-VFQ25 questionnaire was utilized asking patients regarding their subjective functional vision and satisfaction in daily life before and after using the Fresnel prism. RESULTS: After 1 month of Fresnel prism prescription, 53% of patients showed objective visual field expansion to the defective field of 12.5 degrees on average. Monocular or macular splitting hemianopsia patients showed more visual field expansion than binocular macular sparing hemianopsia patients. The NEI-VFQ25 score increased significantly and abnormal head position decreased or disappeared after 1 month of using the prism. However, 47% of patients failed to adapt to the prism. CONCLUSIONS: Using Fresnel prism in homonymous hemianopsia patients effectively expands the visual field, corrects abnormal head position, and improves functional vision. However, to improve the success rate, for certain patients the proper choice of prism application method, prism diopters, and constant management are necessary.