Optic Nerve Fenestration in a Patient With the Syndrome of Acquired Hyperopia and Choroidal Folds

A 5-year-old boy developed profound loss of vision in his right eye and was found to have a 11778 mitochondrial point mutation consistent with Leber hereditary optic neuropathy (LHON). He maintained 20/20 vision in the left eye for 18 years until age 23, when he experienced loss of vision in that eye. This 18 year interval between eye involvement in LHON is the longest reported to date and reinforces the variability in presentation and progression seen in this disease.

Clinical Observation Optic Nerve Fenestration in a Patient With the Syndrome of Acquired Hyperopia and Choroidal Folds Ore-ofe O. Adesina, MD, Judith E.A. Warner, MD, Bhupendra C.K. Patel, MD Abstract: We performed bilateral optic nerve sheath fenestrations on a patient with the syndrome of acquired hyperopia and choroidal folds. We are unaware of previous reports of this procedure being performed in this clinical setting. Despite the incomplete resolution of his posterior segment findings postoperatively, the results of the procedure, along with an understanding of the relevant anatomy, may help to shed light on the pathogenesis of this rare entity. Journal of Neuro-Ophthalmology 2016;36:294-298 doi: 10.1097/WNO.0000000000000364 © 2016 by North American Neuro-Ophthalmology Society T he syndrome of acquired hyperopia and choroidal folds (SAHCF) is characterized by the subacute onset of unilateral or bilateral hyperopia associated with the presence of choroidal folds, flattening of the posterior globe, and dilation of the perioptic nerve sheath, best demonstrated on magnetic resonance imaging (MRI). There is a variable association with optic disc edema, and the syndrome has been described both with and without elevated intracranial pressure (1-6). To date, there is no consensus as to the definitive pathogenesis of the syndrome and no specific treatment. We describe a patient with SAHCF who underwent bilateral optic nerve sheath fenestrations. To our Ruiz Department of Ophthalmology and Visual Science (O-oOA), The University of Texas Medical School at Houston, Houston, Texas; Robert Cizik Eye Clinic (O-oOA), Houston, Texas; John A. Moran Eye Center, Department of Ophthalmology and Visual Sciences (O-oOA, JEAW, BCKP), The University of Utah School of Medicine, Salt Lake City, Utah; Department of Neurology (JEAW), The University of Utah School of Medicine, Salt Lake City, Utah. Supported in part by National Eye Institute Vision Core Grant P30EY010608, a Challenge Grant to The University of Texas Medical School from Research to Prevent Blindness, an Unrestricted Grant to The University of Utah Medical School from Research to Prevent Blindness, and the Hermann Eye Fund. The authors report no conflicts of interest. Address correspondence to Ore-ofe O. Adesina, MD, Robert Cizik Eye Clinic, 6400 Fannin Street, Suite 1800, Houston, TX 77030; E-mail: [e-mail] 294 knowledge, this is an approach to SAHCF that has not been described previously. CASE REPORT A healthy 32-year-old man reported the subacute onset of bilateral blurry vision and headaches. Initial evaluation by his optometrist revealed a significant hyperopic change in his prescription. When he did not experience normalization of his visual acuity with new spectacles, he was evaluated by an ophthalmologist, whose examination revealed bilateral optic disc edema and choroidal folds. Computed tomography of the brain was unremarkable, whereas MRI demonstrated bilateral optic nerve sheath dilation and posterior flattening of the globes (Fig. 1). Lumbar puncture performed in the fetal position without legs extended revealed an opening pressure of 27-cm H2O and normal cerebrospinal fluid (CSF) composition. He was diagnosed with idiopathic intracranial hypertension (IIH) started on 500 mg of oral acetazolamide daily and referred for neuroophthalmic evaluation. The patient denied a history of pulse synchronous tinnitus, transient visual obscurations, diplopia, micropsia, macropsia, metamorphopsia, or changes in color vision. He had a history of migraine since his teens that had not changed in the past decade. He denied any recent weight gain, use of steroids, tetracycline antibiotics, lithium, or vitamin A derivatives. He did not report significant improvement in his headaches after lumbar puncture or while taking acetazolamide. His body mass index was 32 mg/m2. Visual acuity in both eyes was 20/40 with a refraction of +0.75 + 0.75 · 028, right eye, and +1.25 + 0.75 · 170, left eye. Cycloplegic refraction was +3.50 + 0.75 · 028, right eye, and +3.00 + 0.50 · 170, left eye, with 20/30 vision bilaterally. Pupillary testing and intraocular pressures were normal. There was no evidence of anterior segment inflammation. Ophthalmoscopy revealed bilateral mild optic disc edema and choroidal folds (Fig. 2). Optical coherence Adesina et al: J Neuro-Ophthalmol 2016; 36: 294-298 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation FIG. 1. Axial (A) and coronal (B) T2 magnetic resonance images show flattening of the posterior globes and dilation of the optic nerve sheaths. tomography (OCT) confirmed the presence of retinochoroidal folds without intraretinal or subretinal fluid (Fig. 2). Automated visual fields (Carl Zeiss Meditec, Inc, Dublin, CA) demonstrated enlargement of the physiologic blind spots. B-scan ultrasonography exhibited bilateral posterior globe flattening without optic nerve drusen or posterior scleritis. Opening pressure on repeat lumbar puncture was 22cm H2O with normal CSF composition. Complete blood count, metabolic panel, cortisol, and thyroid levels were normal. A sleep study was normal, as was rheumatologic work-up. The patient continued on 500 mg of oral acetazolamide daily and lost 30 pounds, without improvement in his vision, fundus appearance, or headaches. The constellation of examination and neuroimaging findings were consistent with SAHCF. Because of his persistent reduced vision and neuroimaging evidence of optic nerve sheath dilation with posterior globe flattening, he was referred for consideration for optic nerve sheath fenestration (ONSF). After obtaining informed consent, the patient underwent uncomplicated bilateral ONSF through an anterior orbitotomy approach via a superomedial eyelid crease incisions. The optic nerve sheaths were fenestrated by creating approximately 3 mm by 3 mm windows that allowed egress of CSF. One week postopoeratively, the patient had stable visual acuity of 20/30 bilaterally with his previous spectacle correction. Visual fields and choroidal folds were unchanged but there was mild improvement in optic disc edema FIG. 2. There is bilateral optic disc edema (right greater than left) and choroidal folds. Spectral domain optical coherence tomography (bottom panels) confirms the presence of choroidal folds. Adesina et al: J Neuro-Ophthalmol 2016; 36: 294-298 295 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation bilaterally. He was continued on 500 mg of oral acetazolamide. At follow-up 8 weeks later, his best-corrected visual acuity was 20/25 bilaterally. Follow-up OCT of the retinal nerve fiber layer and macula showed no changes, and B-scan ultrasonography demonstrated no significant reduction in nerve fiber layer thickness with continued posterior flattening of the globes. When seen 20 months postoperatively, the patient was no longer taking acetazolamide and had regained 30 lbs. He reported stable subjectively blurry vision in both eyes and less frequent headaches. He denied pulsatile tinnitus, diplopia, and transient visual obscurations. His visual acuity was 20/25 bilaterally with a cycloplegic refraction of +3.50 + 1.50 · 010, right eye, and 2.50 + 1.00 · 165, left eye. Ophthalmoscopy showed a slight reduction in optic disc edema in both eyes (Fig. 3), whereas the appearance of the choroidal folds was unchanged clinically and by OCT. Automated perimetry also was unchanged. DISCUSSION In 1979, Kalina and Mills (4) reported a syndrome of benign acquired hyperopia with choroidal folds in 6 healthy adults. Subsequent reports in the literature have characterized the hallmarks of SAHCF, including choroidal folds, optic disc edema, acquired hyperopia, flattening of the posterior globe, and dilation of the subarachnoid perineural space, with stable visual acuity and refraction over time. Bird and Sanders (6) documented 2 patients with IIH and similar clinical findings, whereas Jacobson (3) described 3 patients with bilateral optic disc edema, acquired hyperopia, and choroidal folds, 2 of who had elevated opening pressure on lumbar puncture. Despite the association with elevated intracranial pressure, Jacobson proposed that SAHCF represented a heterogeneous group of disorders distinct from IIH, with elevated intracranial pressure representing 1 end of the disease spectrum. Our patient demonstrated all features of SAHCF. His first lumbar puncture was performed in the fetal position, bringing into question the accuracy of the opening pressure measurement. His headaches were long-standing and migrainous in nature and did not significantly improve after either lumbar puncture or treatment with acetazolamide. He did not have any associated symptoms of elevated intracranial pressure. His long-term follow-up demonstrated improvement in his headaches and optic disc edema despite being off acetazolamide for over a year and regaining 30 lbs. His hyperopic shift in refraction was the result of choroidal folds and posterior globe flattening. His overall clinical picture was consistent with a diagnosis of SAHCF, and not IIH. The management of SAHCF has involved observation, optical correction, and medical management of the underlying cause of elevated intracranial pressure, if present. Optic nerve sheath fenestration has not been reported as a treatment. The procedure was offered to our patient in an attempt to decompress the retrobulbar dilation of the nerve sheaths and attendant posterior globe flattening. Our patient did demonstrate some subjective improvement in visual acuity in the initial postoperative period; however, there was no significant functional or anatomical improvement at his 8-week postoperative visit. The persistence of our patient's choroidal folds and disc edema in the immediate postoperative period may reflect the chronicity of their presence before surgical intervention or because of failure of the ONSF procedure through closure of the fenestrations. We believe that the latter possibility is unlikely because of the creation of large windows in optic nerve. At 20-month follow-up, there was a reduction in his optic nerve edema on OCT, without a change in his choroidal folds or visual function. From our patient's clinical course, we conclude that 1) abnormalities of the posterior globe and dural sheath are likely the cause of both his choroidal folds and disc edema; 2) the retrobulbar dilation of the nerve sheaths FIG. 3. At 20-month postoperative examination, there is slight reduction in optic disc edema in each eye. 296 Adesina et al: J Neuro-Ophthalmol 2016; 36: 294-298 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation FIG. 4. Schematic drawing of the optic nerve demonstrating the difference in architectural configuration of trabeculae and septae in the 3 segments of the nerve (Modified from [7]). is likely not from increased CSF pressure; and 3) most of his nonrefractive vision loss was due to the presence of choroidal folds rather than optic neuropathy from his disc edema. Killer et al (7) have elegantly detailed the complex anatomy of the perioptic subarachnoid space in humans and its potential effect on CSF flow (Fig. 4). Through electron micrographic study, they showed that there is considerable structural variability of the meshwork of trabeculae, septa, and supporting pillars that are arranged between the arachnoid and pia layers of the meninges of the optic nerve. The spacing of trabeculae and septae is widest in the bulbar segment and becomes more compact as the subarachnoid space narrows in the midorbital and intracanalicular segments. The presence of septa also diminishes more proximally, disappearing in the intracanalicular segment. Hayreh (8) also studied the anatomy of the fibrous septa of the perioptic subarachnoid space in monkeys and humans. He found that the number of the bands varies from individual to individual and observed that when dye is injected into the subarachnoid space, fluid generally passes easily into the cranial cavity, with the force needed dependent on the quality and quantity of the fibrous bands within the subarachnoid space. Given these anatomic findings, we propose that in individuals with SAHCF, there is weakness or instability of the collagen structure of the sclera of the posterior globe and dural sheath of the retrobulbar optic nerve as they fuse. Adesina et al: J Neuro-Ophthalmol 2016; 36: 294-298 This causes altered compliance which, along with variations in the number and spacing of the subarachnoid trabeculae and septae, could promote local CSF entrapment in the bulbar segment of the SAS through a 1-way valve effect. A local relative rise in CSF pressure, either transiently or chronically, could trigger optic nerve sheath dilation and cause globe flattening, resulting in the of SAHCF. Hopefully, further anatomic and physiologic studies in patients with SAHCF will test our proposed pathogenic mechanism of this syndrome. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: O.-o. O. Adesina, J. E.A. Warner, and B. C.K. Patel; b. acquisition of data: O.-o. O. Adesina, J. E.A. Warner, and B. C.K. Patel; c. analysis and interpretation of data: O.-o. O. Adesina, J. E.A. Warner, and B. C.K. Patel. Category 2: a. Drafting the manuscript: O.-o. O. Adesina, J. E.A. Warner, and B. C.K. Patel; b. Revising it for intellectual content: O.-o. O. Adesina, J. E.A. Warner, and B. C.K. Patel. Category 3: a. Final approval of the completed manuscript: O.-o. O. Adesina, J. E.A. Warner, and B. C.K. Patel. REFERENCES 1. Cassidy LM, Sanders MD. Choroidal folds and papilloedema. Br J Ophthalmol. 1999;83:1139-1143. 2. Griebel SR, Kosmorsky GS. Choroidal folds associated with increased intracranial pressure. Am J Ophthalmol. 2000;129:513-516. 297 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation 3. Jacobson DM. Intracranial hypertension and the syndrome of acquired hyperopia with choroidal folds. J Neuroophthalmol. 1995;15:178-185. 4. Kalina RE, Mills RP. Acquired hyperopia with choroidal folds. Ophthalmology. 1980;87:44-50. 5. Sharma M, Volpe NJ, Patel T, Kimmel A. Intracranial hypertension associated with acquired hyperopia and choroidal folds. Retina. 1999;19:260-262. 298 6. Bird AC, Sanders MD. Choroidal folds in association with papilloedema. Br J Ophthalmol. 1973;57:89-97. 7. Killer HE, Laeng HR, Flammer J, Groscurth P. Architecture of arachnoid trabeculae, pillars, and septa in the subarachnoid space of the human optic nerve: anatomy and clinical considerations. Br J Ophthalmol. 2003;87:777-781. 8. Hayreh SS. The sheath of the optic nerve. Ophthalmologica. 1984;189:54-63. Adesina et al: J Neuro-Ophthalmol 2016; 36: 294-298 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.