Background <p>Anisocoria following severe head injury is traditionally interpreted as an impending neurological emergency, often prompting immediate empiric interventions for presumed intracranial hypertension. However, traumatic ocular injuries can present with identical pupillary findings, creating a critical diagnostic dilemma in the unresponsive trauma patient.</p> Case presentation <p>We present the case of a 70-year-old intubated male with a severe traumatic brain injury who presented with a unilateral fixed, dilated pupil. Because urgent transport for head computed tomography (CT) was delayed due to severe respiratory acidosis from an obstructed endotracheal tube, bedside ocular point-of-care ultrasound (POCUS) was performed to evaluate for ocular mimics of cerebral herniation. Using a minimal-pressure technique after excluding globe rupture, POCUS identified a posterior dislocation of the crystalline lens into the vitreous cavity. This rapid identification of a mechanical ocular etiology for the anisocoria successfully prevented the immediate management for brain herniation. Subsequent CT confirmed the ultrasound findings, and the patient ultimately underwent lensectomy and iris repair.</p> Conclusions <p>This case underscores the utility of screening ocular ultrasound in differentiating mechanical ocular complications from intracranial pathology in the acute trauma setting. POCUS serves as an invaluable extension of the physical examination when traditional neurological assessment is limited by sedation, paralysis, or intubation, thereby refining initial resuscitation pathways and avoiding unnecessary neuro-directed interventions alone.</p>