Supplementary Material for: Isolated Idiopathic Inferior Rectus Palsy: A Case Report and Literature Review

Purpose: To report a rare case of isolated idiopathic inferior rectus (IR) palsy in a young adult and discuss its clinical features, diagnostic workup, and surgical management. Methods: A 31-year-old male presented with a 3-month history of vertical diplopia and right hypertropia. Comprehensive ophthalmic and systemic evaluations, including imaging and laboratory tests, were conducted. Results: Examinations revealed right IR underaction with a 30 prism diopter (PD) hypertropia in primary gaze. Forced duction testing was negative. Imaging and laboratory investigations were unremarkable. The patient underwent an 8 mm ipsilateral superior rectus (SR) recession. Postoperatively, orthotropia was achieved with resolution of diplopia. Conclusions: Isolated idiopathic IR palsy is exceedingly rare. Thorough evaluation is essential to exclude secondary causes. Ipsilateral SR recession can provide excellent functional and cosmetic outcomes in patients with persistent hypertropia and diplopia.