Direct measurements of intracranial pressure (ICP) by lumbar puncture (LP) remain the criterion standard for diagnosing, following, and treating specific neurologic, neurosurgical, and neuro-ophthalmic conditions with elevated ICP. In this issue of JAMA Ophthalmology, Wang et al1 used ultrasonography to document optic nerve sheath diameter (ONSD), and their results reported a correlation between noninvasive ultrasonography and dynamically monitored ICP.