Avulsion of the Optic Nerve Head
A forceful backward dislocation of the optic nerve from the scleral canal can occur under several circumstances, including
extreme rotation and forward displacement of the globe
penetrating orbital injury, causing a backward pull on the optic nerve
sudden increase in IOP, causing rupture of the lamina cribrosa
Total loss of vision characteristically occurs. Findings may vary from a pitlike depression of the optic nerve head to posterior hemorrhage and contusion necrosis (Fig 18-7); however, hemorrhage is usually present acutely. A B-scan ultrasound may reveal a hypoechoic defect in the area of the posterior scleral defect in the region of the optic nerve (ON). Cross-sectional neuroimaging may also be helpful in making the diagnosis.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.