A 26-year-old man was struck in his unprotected left eye by a paintball and noted immediate, complete vision loss. The paintball did not burst upon impact.

Visual acuities were 20/20 OD and no light perception OS. The right eye was normal. The left eye demonstrated incomplete ophthalmoplegia, an afferent and efferent pupillary defect, chemosis, corneal oedema, a small hyphaema, and iridodialysis. Fundus examination revealed vitreous haemorrhage, obscuring the optic nerve, and a giant retinal tear. Ultrasonography (Figure 1) and orbital magnetic resonance imaging (MRI, Figure 2) utilising T1, T2, and fat-suppression techniques demonstrated no abnormality of the optic nerve.

Figure 1
figure 1

Retrobulbar optic nerve appears normal on ultrasonography (B scan, 10 MHz).

Figure 2
figure 2

Retrobulbar optic nerve appears normal on MRI (high resolution, axial T2 weighted image).

The patient underwent enucleation the following week for a blind painful eye. The optic nerve sheath remained attached to the intact globe with no apparent injury to the optic nerve. Histology revealed avulsion of the optic nerve head (posterior dislocation of the lamina cribrosa). Blood filled the cavity left by the avulsed nerve within the intact dural sheath (Figure 3).

Figure 3
figure 3

Optic nerve avulsion injury with posterior dislocation of lamina cribrosa within an intact dural sheath. The posterior third of the lamina cribrosa is disconnected from the proximal two-thirds (H&E stain, magnification × 20 and × 100).

Comment

Ocular paintball injuries are well described.1, 2 Types of injuries include corneal rupture, hyphaema, lenticular damage, vitreous haemorrhage, retinal tear/detachment, and optic neuropathy.1 Optic nerve head avulsion occurs in the setting of blunt trauma to the eye.

A sudden rise in intraocular pressure or sudden rotation of the globe may lead to retrodisplacement of the nerve head within the robust sheath.3, 4 Avulsion may be difficult to diagnose when the nerve head cannot be visualised on fundus examination. Additionally, imaging often does not reveal the diagnosis since the dural sheath remains attached to the globe.5, 6, 7

Histopathology of the injury may explain the oftentimes-normal imaging studies.3 In our patient, the size of the recession was small with blood filling the space created by the avulsion. This combination and intact dural sheath seem to obscure imaging of this injury.

Paintball injury may result in optic nerve head avulsion. The diagnosis should be suspected in a patient with no light perception vision after blunt ocular injury to an intact globe. MRI and ultrasonography usually do not support the clinical diagnosis. Our case represents a rare case of histopathologic confirmation of traumatic optic nerve head avulsion and offers insight into possible reasons for the difficulty of accurate diagnosis with available imaging techniques.