Nervus opticus āvulsiō: Acute to chronic

Optic nerve avulsion (ONA) is a rare, visually devastating complication that can occur following trauma. It may be partial or complete and can be associated with ocular or orbital injuries. ONA has been reported after finger-poke, animal kicks, sports injuries, falls, and road traffic accidents (RTAs) and has been documented since 1901.1–3 Several mechanisms have been postulated, including sudden forced rotation of the globe, a sudden increase in intraocular pressure leading to tearing of lamina cribrosa/sclera, and sudden forward displacement of the globe due to raised intraorbital pressure causing hyperextension and tearing of the optic nerve fibers.4 Clinical diagnosis is challenging if the optic disc is obscured by vitreous hemorrhage or any media haze. In such cases, ultrasonography, electrodiagnostic tests, and neuroimaging are useful to substantiate the diagnosis. Herein, we describe three cases of optic nerve avulsion Fig. 1a-c with different onset of presentation (acute, subacute, and chronic) and their distinct fundus findings. Case 1 with acute presentation, ophthalmoscopy demonstrated central retinal artery occlusion; however, the optic disc showed a deep cup, which raised suspicion of ONA, and the patient was further investigated with OCT and MRI. SS-OCT showed a deep optic nerve cup with inner retinal hyperreflectivity suggestive of severe ischemia. MRI orbit revealed avulsion of the optic nerve at the lamina with hemorrhages around the optic disc. Cases 2 and 3 had striking fundus findings that were clinically in favor of optic nerve avulsion.Figure 1: (a) A 13-year-old boy (Case 1) had OS vision loss 3 days post cricket bat injury. Fundus showed fresh vitreous hemorrhage, retinal whitening at the posterior pole, optic disc excavation, and hemorrhages surrounding the disc. (b) A 22-year-old male (Case 2) had OD vision loss post-RTA 2 months prior. Fundus showed fibroglial scarring of disc and old vitreous hemorrhage. (c) A 26-year-old male (Case 3) with sustained head injury 2 years ago had glial tissue over the atrophic disc, attenuated vessels, and peripapillary scarringThe diagnosis is often clinical and quite apparent when the media is clear; however, in difficult cases, radiographic and sonographic correlation is essential. Key clinical features include deep excavation of the disc with or without peripapillary hemorrhages. Ultrasound is helpful in cases where the view is obscured. An increase in the diameter of the optic nerve and hypolucency posterior to the optic nerve head is usually seen Fig. 2a. In complete avulsion, B-scan may show retrodisplacement of the lamina cribrosa and separation of optic nerve shadow from the scleral canal,5 while in certain cases, B-scan can be normal. OCT is effective for detecting deep depression of the optic nerve head and discontinuity between retinal layers and the optic nerve head Fig. 2b, although it is of limited value in cases of opaque media. MRI orbit with a fat-suppressed sequence to reduce the fat signal and a surface-coiling technique that increases the signal–noise ratio have been used to improve the diagnostic potential of MR Fig. 2c. Initial diagnosis can be challenging in certain cases; however, when diagnosed early, it does not warrant unnecessary intervention as there is no proven and effective treatment for optic nerve avulsion.Figure 2: (a) USG B-scan showing widening of the optic nerve head. (b) SS-OCT demonstrates deep excavation of the optic disc with vitreous strands inserting into it and hyperreflectivity of inner retinal layers in the peripapillary area. (c) MRI orbit surface coil technique shows extensive intraocular hemorrhage and avulsion of the left optic nerve with surrounding hemorrhageAuthors’ contributions’ K Padmalakshmi : Manuscript preparation and editing, Data acquisition Nisar Sonam Poonam : Concept and design, Data acquisition and manuscript editing Jaya Prakash Vadivelu: Data acquisition and manuscript editing Selvakumar Ambika: Manuscript editing and review. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published, and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.