Application of Soft Directional Prismatic Contact Lenses to Correct Diplopia

Purpose: To verify whether diplopia due to a small-angle strabismus within 8 prism diopters (PD) could be corrected by applying soft directional prismatic contact lenses, obtaining higher comfort and quality of vision for the patients. Methods: A prospective study was undertaken by enrolling consecutive patients affected by vertical and/or horizontal diplopia and small-angle strabismus within 8 PD. The patients were tested for best corrected visual acuity, refraction, cover test for near and for distance, ocular motility test, prismatic fit test, corneal topography, tear film evaluation, binocular vision test, head position evaluation, retinography, and optical coherence tomography of the posterior and anterior segment. Custom soft contact lenses, made in Benz G5X material, were designed and developed for this study. All patients were first corrected with prismatic glasses according to their degree of strabismus and ametropia. Then they were asked to wear custom-made directional prismatic contact lenses with appropriate simultaneous correction of strabismus and ametropia. The patients were then asked to answer whether the comfort and quality of vision was higher with directional prismatic contact lenses or prismatic glasses. Results: Eight patients were enrolled with different causes of diplopia caused by a strabismus of 8 PD or less. The soft directional prismatic contact lenses could resolve diplopia in 100% of patients. All patients reported greater comfort and quality of vision with directional prismatic contact lenses. Conclusions: The study demonstrated that diplopia resulting from an angle of strabismus within 8 PD can be corrected through the use of soft directional prismatic contact lenses, obtaining greater quality of vision free of aberrations.