Indirect optic nerve injury

≈ 5% of head trauma patients manifest an associated injury to some portion of the visual system. Approximately 0.5–1.5% of head trauma patients will sustain indirect injury (as opposed to penetrating trauma) to the optic nerve, most often from an ipsilateral blow to the head (usually frontal, occasionally temporal, rarely occipital).

The intracanalicular segment is the most common one damaged with closed head injuries. Funduscopic abnormalities visible on initial exam indicates anterior injuries (injury to the intraocular segment (optic disc) or the 10–15 mm of the intraorbital segment immediately behind the globe where the central retinal artery is contained within the optic nerve), whereas posterior injuries (occurring posterior to this but anterior to the chiasm) takes 4–8 weeks to show signs of disc pallor and loss of the retinal nerve fiber layer.

Visual loss due to optic nerve injury after closed traumatic brain injury constitutes a formidable diagnostic and therapeutic challenge for the clinician. Assessment must be made of the site of optic nerve injury, and this is often difficult in the patient with an altered level of consciousness. A decision regarding optic nerve decompression must be formulated, yet the literature is confusing with regard to operative indications.

If conscious: serial quantification of vision in each eye is important ¹⁾.

Care must be taken to avoid optic nerve injury caused by the retraction and/or the heat of the drill when doing ophthalmic artery aneurysm surgery ²⁾.

Optic nerve decompression has been advocated for indirect optic nerve injury; however, the results are not clearly better than expectant management with the exception that documented delayed visual loss appears to be a strong indication for surgery. The transethmoidal approach is the accepted route and is usually done within 1–3 weeks from the trauma. use of “megadose steroids” may be appropriate as an adjunct to diagnosis and treatment.