Optometry & Visual Performance 252 Volume 13 | Issue 4 | December 2025 Article • Effectiveness of Vision Therapy for Divergence Insufficiency: A Case Series Santosh Chhetri, M. Optom • Metro Eye Care & Shrawan Autism Center • Butwal, Nepal Umesh Belbase, M. Optom • Metro Eye Care • Butwal, Nepal Mario Cantó-Cerdán, DO, PhD • Vissum (Miranza) & University of Alicante • Alicante, Spain Aashish Kant Shah, M. Optom • Biratnagar Eye Hospital • Biratnagar, Nepal ABSTRACT Background: When base-out prism glasses are not successful in maintaining binocularity and eliminating symptoms in divergence insufficiency, vision therapy serves as a viable non-surgical treatment option. We report three cases of patients with divergence insufficiency who improved negative fusional vergence, eliminated symptoms, maintained binocularity, and achieved stereopsis through vision therapy. Case one: An 18-year-old female student presented with complaints of an occipital headache and occasional double vision, which was more pronounced at a distance and in the evening for the past four years. Orthoptic evaluation led to a diagnosis of divergence insufficiency. She was treated with base-out prism glasses and vision therapy. Over five months, the prism glasses were gradually weaned off, and the patient became asymptomatic with well-controlled deviation. Case two: A 35-year-old male driver had to leave his job due to double vision. He had been using prism glasses for the past ten years. However, his negative fusional vergence and prism glasses were insufficient to control the deviation. After several sessions of vision therapy, his double vision was eliminated, and he was able to resume driving. Introduction Divergence insufficiency (DI) is an uncommon condition that is characterized by a concomitant esodeviation that is greater at a distance than near.1 DI in adults accounts for 10.6% of adult strabismus cases in population-based studies2 and 0.1% to 7.0% in subjects without strabismus.3-5 The etiology of DI remains unclear. There are different hypotheses, including age-related degeneration of the orbital connective tissues6 and the shortening or increased tone of the medial rectus muscles.7,8 Studies suggest that DI, divergence paresis, and divergence paralysis are part of a continuum of the same condition, differing only in their clinical and neurological findings.9 Various treatments are used to manage DI, such as refractive correction,10 base-out prism correction,11 divergence exercises or vision therapy,10,12 and strabismus surgery.8,13,14 Prism correction or surgery is usually the first line of treatment.15 There is limited literature available on the effectiveness of vision therapy for DI.16 This case series describes patients with DI who were managed with prism correction Santosh Chhetri, M. Optom Butwal, Nepal B.Optom, MAKAUT, India M.Optom, Tilganga Institute of Ophthalmology, Nepal Fellowship in Binocular vision, Pediatric and Neuro Optometry, Dr. Shroff Eye Hospital, India Consultant Pediatric and Neurodevelopmental Optometrist, Metro Eye Care Lumbini & Shrawan Autism Center, Nepal Lecturer, Pokhara University Case 3: A 12-year-old female student had headaches, usually while focusing on the board at school. She was diagnosed with left eye suppression and divergence insufficiency. After several sessions of office and home-based vision therapy, she experienced relief from symptoms and achieved binocularity and stereopsis. Conclusion: Vision therapy is a non-surgical treatment approach for divergence insufficiency and offers an effective and promising alternative to surgical intervention. These three cases highlight successful and positive outcomes in patients with divergence insufficiency. Keywords: divergence insufficiency, divergence therapy, prism glasses, vision therapy
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