Traumatic Cataract Following Accidental HIFU Exposure of the Upper Eyelid: A Rare Ocular Complication—Case Report

High-intensity focused ultrasound (HIFU) is increasingly used for noninvasive facial tightening, but inadvertent exposure of the periocular region may injure ocular structures. We present a 34-year-old woman who developed sudden visual deterioration approximately 30 min after facial HIFU when the applicator accidentally moved onto the right upper eyelid. Best-corrected visual acuity (BCVA), measured using Snellen charts, was 0.2 in decimal scale in the right eye and 1.0 in the left eye, with intraocular pressure of 17 and 14 mmHg, respectively. Slit-lamp examination revealed a slightly dilated, sluggish pupil and dense inferior lens opacity with a rosette-shaped opacity involving the posterior lens, while the eyelid skin and cornea remained intact. Anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy showed no capsular rupture; ultrasound biomicroscopy additionally demonstrated separation of cortical lens material from the posterior capsule. BCVA progressively decreased to 0.04 before cataract surgery. Phacoemulsification with implantation of a non-diffractive spiral intraocular lens was performed two months after the HIFU exposure. On postoperative day 1, uncorrected visual acuity was 1.0 at distance and 0.5 at near, with intraocular pressure of 16 mmHg, and these findings remained stable during six months of follow-up. Posterior segment OCT and visual field testing showed no clinically relevant abnormalities. The images illustrate a characteristic pattern of traumatic cataract following inadvertent periocular HIFU exposure and the multimodal imaging used for diagnosis and follow-up. This case emphasizes that lens injury may occur despite an intact cornea and eyelid and supports strict avoidance of direct HIFU application to the eyelids, together with appropriate ocular protection.