[Contusion of the optic nerve after minor blunt ocular trauma: case report and literature review]

Abstract

Introduction: Isolated trauma of the optic nerve usually occurs in association with blunt skull trauma involving fractures of the skull and optic canal, but rarely occurs from blunt ocular trauma.

Case report: A 7-year old boy fell and struck his left eye against a toy antenna. The initial examination revealed a visual acuity of 0.2 and slight edema of the optic nerve head. Perimetry revealed a defect in the superior and nasal visual fields. CT and MRI scans of the orbit were normal. Nine months after the injury, vision had improved to 1.0. On examination, optic nerve atrophy had developed and perimetry continued to display a defect in the superior visual fields.

Discussion: The mechanism of optic nerve damage secondary to trauma can be classified as primary or secondary. Primary damage occurs as a result of external forces at the moment of trauma, e.g., rupture of nerve fibers or of capillary vessels. Secondary damage may not be present initially, but may occur later on and results from compromised blood supply to the optic nerve, e.g., following edema or angiospasm. In our patient, it is not clear whether the damage was primary or secondary.

Conclusion: Damage to the optic nerve can be caused by blunt skull trauma and, rarely, also by blunt ocular trauma. This fact is of importance when considering legal and reimbursement issues.