Spontaneous Globe Luxation-Induced Optic Neuropathy

Clinical Correspondence Section Editors: Robert Avery, DO Karl C. Golnik, MD Spontaneous Globe Luxation–Induced Optic Neuropathy Danny A. Mammo, MD, Yao Wang, MD, Michael S. Lee, MD, Ali Mokhtarzadeh, MD, Andrew R. Harrison, MD, Collin M. McClelland, MD Downloaded from http://journals.lww.com/jneuro-ophthalmology by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3i3D0OdRyi7TvSFl4Cf3VC4/OAVpDDa8K2+Ya6H515kE= on 05/04/2022 G lobe luxation is a rare phenomenon that occurs spontaneously, post-traumatically, or voluntarily (1). There are 2 reported cases of voluntary globe luxation leading to optic neuropathy: one in a teenager with a proclivity to repeatedly luxate his globe on prodding from his friends and the other in a 35-year-old man with severe obsessive compulsive disorder (2,3). Spontaneous globe luxation has also been associated with ill-defined vision loss (4). We report an unusual case of progressive unilateral optic neuropathy in a young man with obstructive sleep apnea, structurally shallow orbits, and floppy eyelid syndrome who suffered hundreds of episodes of spontaneous left globe luxation. A 36-year-old African American man presented with a 3year history of progressive vision loss in the left eye. Initially, he felt he noticed blurry vision in the left eye after a motor vehicle accident in which he struck the side of his head on the window without loss of consciousness. An ophthalmology examination 7 months later was notable for visual acuity (VA) of 20/20, right eye, and 20/30, left eye. He had a left relative afferent pupillary defect (RAPD) and mild left optic nerve pallor. MRI of the brain and orbits with and without contrast revealed an incidental Chiari 1 malformation with 5-mm cerebellar tonsillar herniation, bilateral proptosis without an apparent structural etiology, and T2 hyperintensity within the left optic nerve without enhancement. A limited serum laboratory work-up revealed a normal thyroid-stimulating immunoglobulin (TSI), antithyroid peroxidase, and negative Borrelia burgdorferi antibodies. Upon presentation to our clinic 3 years later, the patient described progressive worsening of vision in his left eye. The medical history was significant for moderately controlled type II diabetes mellitus, hypertension, hyperlipidemia, stage II chronic kidney disease, asymptomatic mild Chiari I malformation, and untreated obstructive sleep apnea (noncompliant with continuous positive airway pressure [CPAP] machine). Medications included lisinopril, atorvastatin, glimepiride, and aspirin. He denied smoking and Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota. The authors report no conflicts of interest. Address correspondence to Collin M. McClelland, MD, Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 420 Delaware St SE, Minneapolis, MN 55455; E-mail: [e-mail] e54 occasionally drank alcohol. Family history was negative for any ophthalmic or neurologic disorders. On examination, VA measured 20/15, right eye, and no light perception, left eye. To light, the right pupil was briskly reactive and the left was amaurotic. There was a brisk left RAPD. Intraocular pressures and extraocular movements were normal in both eyes, as well as confrontational visual fields and color plates in the right eye. External examination revealed severe bilateral floppy eyelids and proptosis (Fig. 1A–C). Hertel exophthalmometry measured 28 and 29 mm in the right and left eye, respectively, without resistance to retropulsion. Anterior segment examination was normal in both eyes, and dilated examination was significant for severe left optic nerve pallor. Further history revealed that the patient experienced frequent recurrent episodes of vision loss in the left eye. He described, “my eye would literally pop out and I had to push it back in.” His vision would return to baseline within an hour. He estimated he had suffered hundreds of luxation episodes over the prior decade in the left eye and only a “handful” in the right eye. Octopus 30-2 automated perimetry was full, right eye. Optical coherence tomography (OCT) of the retinal nerve fiber layer (RNFL) demonstrated mild temporal thinning in the right eye and diffuse severe thinning in the left eye with considerable interval progression of RNFL thinning over a 3-year period (Fig. 2). OCT of the left macula revealed RNFL and ganglion cell layer thinning with preservation of the remainder of the retinal layers on segmentation analysis. Repeat MRI of the brain and orbits with and without IV contrast displayed an unchanged Chiari malformation and bilateral proptosis without extraocular muscle enlargement or other orbital pathology. MRI again demonstrated T2 hyperintensity of the left optic nerve in the absence of enhancement on postcontrast T1 sequences (Fig. 3). Both of his MRI studies included dedicated orbital sequences and were interpreted formally by neuro-radiologists followed later by an informal review by 2 fellowship-trained neuroophthalmologists, none of whom appreciated optic nerve enhancement. Serum TSI, thyroid-stimulating hormone, free T3, and free T4 were normal. Given the significant degree of proptosis, floppy eyelids, and compelling clinical history in the absence of another more plausible explanation after careful neuro-ophthalmic examination and review of all neuro-imaging, a clinical diagnosis of spontaneous globe luxation–induced optic Mammo et al: J Neuro-Ophthalmol 2021; 41: e54-e56 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence FIG. 1. External photographs demonstrating bilateral proptosis and prominent laxity of the right, (A), and left, (B and C), eyelids with light manual manipulation, indicative of floppy eyelid syndrome. neuropathy was made. After a thorough discussion regarding potential management options, our patient opted to undergo bilateral orbital fat and lateral wall decompression. He was additionally encouraged to lose weight and reinitiate CPAP treatment. Ten months postoperatively, the patient reported no further luxations in either eye. His postoperative Hertel exophthalmometry measurements improved 2 mm, right eye, and 3 mm, left eye, and measured 26 mm in both eyes. FIG. 2. Left eye spectral-domain OCT RNFL analysis from the same model machine demonstrating significant interval progression in the diffuse RNFL thinning over a 3-year period from the initial documented examination (A) to our examination (B). OCT, optical coherence tomography; RNFL, retinal nerve fiber layer. Mammo et al: J Neuro-Ophthalmol 2021; 41: e54-e56 Risk factors for globe luxation include shallow orbits, floppy eyelids, thyroid eye disease, and craniofacial anomalies (5). Common sequelae include exposure keratitis and eye irritation. Less commonly, luxation can lead to corneal perforation or optic neuropathy (2). FIG. 3. A. Coronal T1 fat suppressed, post-contrast MRI (MRI) sequence through the mid-orbit demonstrating no optic nerve enhancement. B. Axial T2 MRI sequence demonstrating hyperintensity and atrophy of the left optic nerve. e55 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence Our case highlights that chronic, recurrent spontaneous globe luxation can lead to severe progressive vision loss from optic atrophy. In this case, the optic neuropathy likely occurred secondary to innumerable luxation episodes causing mechanical, stretch-induced trauma to the retinal ganglion cell axons composing the optic nerve and/or impairment of the vascular supply to the optic nerve (3). Dramatic rises in intraocular pressure during luxation episodes could have also contributed although he did not demonstrate the typical features of glaucomatous optic neuropathy. Similarly, trauma-associated chronic glaucoma was improbable considering the severe optic atrophy in the absence of significant cupping, 4 examinations documenting intraocular pressures of 12–19 and 13–19 in the right and left eye, respectively, a negative family history of glaucoma, and an atypical pattern of OCT RNFL loss for glaucoma. One other case of spontaneous globe luxation reported “complete vision loss” during the episode with full visual recovery shortly after the eye was reduced (4). Previously mentioned cases of optic neuropathies secondary to voluntary luxations included a case of acute, irreversible vision loss to the level of no light perception and a case of reversible optic neuropathy returning back to 20/20 (2,3). Our case is unique in that the optic neuropathy progressed chronically as a result of longstanding, recurrent spontaneous luxations. Although this patient initially noted vision loss after a motor vehicle accident with head trauma and no loss of consciousness, traumatic optic neuropathy is unable to explain his well-documented progression in optic atrophy and vision loss from 20/30 to no light perception over 3 years. It is theoretically plausible that an initial mild indirect, traumatic optic neuropathy may have rendered the left optic nerve more vulnerable to subsequent luxation episodes although this is speculative. Severe head trauma could theoretically predispose to luxation episodes in the setting of distorted orbital anatomy; however, imaging in his case failed to show any evidence of prior orbital fractures. Surgical treatments for spontaneous luxation include partial lateral tarsorrhaphy, pentagonal wedge eyelid resection, advancement of the lateral orbital wall, or orbital decompression (1). Lateral tarsorrhaphy alone potentially increases the risk of luxation by producing a tighter orbit and increased orbital pressure (6). Furthermore if post-tarsorrhaphy luxation occurs, a smaller palpebral fissure might hinder globe reduction. One case series of 7 patients who underwent orbital decompression for spontaneous globe luxations reported no recurrences with a mean follow-up of 10 months (7). Our patient, e56 who unfortunately lost all vision in the left eye, elected to undergo recommended bilateral orbital decompression to prevent any vision loss to the right eye, which also experienced occasional luxations. In summary, in patients with obstructive sleep apnea, floppy eyelids, and proptosis, we recommend considering globe luxation as a potential etiology for either acute or chronic progressive optic neuropathy. Considering globe subluxation–induced optic neuropathy is exceptionally rare, a complete optic neuropathy work-up including neuroimaging should be performed even in the context of a history of globe luxation. In cases of globe luxation with or without vision loss, orbital decompression can be an effective method to prevent future luxation episodes and potentially reduce the risk of new vision loss. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: D. A. Mammo, Y. Wang, M. S. Lee, A. Mokhtarzadeh, A. R. Harrison, and C. M. McClelland; b. Acquisition of data: D. A. Mammo, Y. Wang, A. Mokhtarzadeh, and C. M. McClelland; c. Analysis and interpretation of data: D. A. Mammo, Y. Wang, A. Mokhtarzadeh, and C. M. McClelland. Category 2: a. Drafting the manuscript: D. A. Mammo, Y. Wang, and C. M. McClelland; b. Revising it for intellectual content: D. A. Mammo, Y. Wang, M. S. Lee, A. Mokhtarzadeh, A. R. Harrison, and C. M. McClelland. Category 3: a. 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