Optic nerve sheath diameter

The optic nerve sheath diameter (ONSD) refers to the width of the protective covering surrounding the optic nerve, which transmits visual information from the eye to the brain. Measuring the ONSD, usually via ultrasound, can help assess pressure inside the skull. An increased diameter may indicate swelling or increased intracranial pressure, potentially due to conditions like head injury, brain tumors, or other neurological issues. Tracking changes in the ONSD can aid healthcare professionals in diagnosing and monitoring these conditions, providing crucial information about a patient's brain health.