The optic nerve width refers to the width of the optic nerve bundle, which is approximately 3.58 ± 0.27 mm. The optic nerve can be measured using bedside ultrasound. Widening of the optic nerve bundle can be seen in many diseases such as optic neuritis, optic nerve mass and intracranial hypertension, and changes in the diameter of the optic nerve bundle can reflect changes in intracranial pressure in a timely manner. When the patient’s intracranial pressure increases, eye ultrasound is needed to check whether the optic nerve diameter increases, and antihypertensive treatment should be given in a timely manner, such as rapid sedation of mannitol. The diameter of optic nerve bundle is different for each person. Widening of optic nerve bundle can cause optic papilla edema, leading to significant loss of vision, and in severe cases, it can cause death of optic nerve cells, resulting in permanent visual impairment. It is recommended that patients with abnormal optic nerve width should seek prompt medical attention to evaluate their condition and follow the doctor’s instructions for treatment.