Paracentral Acute Middle Maculopathy Mimicking Retrobulbar Optic Neuropathy

Photo and Video Essay Section Editors: Melissa W. Ko, MD Dean M. Cestari, MD Peter Quiros, MD Paracentral Acute Middle Maculopathy Mimicking Retrobulbar Optic Neuropathy Rachel A. Scott, MD, Nita Bhat, MD, Shruthi Harish Bindiganavile, MD, Helen K. Li, MD, Andrew G. Lee, MD FIG. 1. Automated visual field 24-2 showed paracentral depression in the right eye and nonspecific defect in the left eye. Abstract: A 70-year-old woman presented with acute awareness of decreased color vision in her right eye. Fundus examination and a flash electroretinography (ERG) were both normal. A multifocal ERG (mfERG) however revealed foveal depression, and thinning of inner nuclear layer was noted on macular optical coherence tomography (OCT), and a diagnosis of resolved paracentral acute middle maculopathy was made. Clinicians should be aware of the complementary role of OCT and mfERG in unexplained acute central visual loss to distinguish retinal from neuroophthalmic etiologies. Structural ocular imaging with OCT shows features of inner, middle, and outer retinal localizations to the visual loss. Baylor College of Medicine (RAS, AGL), Houston, Texas; Department of Ophthalmology (NB, SHB, HKL, AGL), Blanton Eye Institute, Houston Methodist Hospital, Houston, Texas; Community Retina Group (HKL), Houston, Texas; The Houston Methodist Research Institute (HKL, AGL), Houston Methodist Hospital, Houston, Texas; Departments of Ophthalmology, Neurology, and Neurosurgery (AGL), Weill Cornell Medicine, New York, New York; Department of Ophthalmology (AGL), University of Texas Medical Branch, Galveston, Texas; University of Texas MD Anderson Cancer Center (AGL), Houston, Texas; Texas A and M College of Medicine (AGL), Bryan, Texas; and Department of Ophthalmology (AGL), The University of Iowa Hospitals and Clinics, Iowa City, Iowa. The authors report no conflicts of interest. Journal of Neuro-Ophthalmology 2021;41:e205–208 doi: 10.1097/WNO.0000000000001041 © 2020 by North American Neuro-Ophthalmology Society Address correspondence to Andrew G. Lee, MD, Blanton Eye Institute, Houston Methodist Hospital, 6560 Fannin Street, Suite 450, Houston, TX 77030; E-mail: [e-mail] Scott et al: J Neuro-Ophthalmol 2021; 41: e205-e208 A 70-year-old woman presented with acute awareness of decreased color vision in her right eye (OD) since 2 years. She was seen by general ophthalmology. Findings included normal fundus examinations, retinal fluorescein angiogram, and a flash electroretinogram. She was then referred to the neuro-ophthalmology service at the Blanton Eye Institute, Houston Methodist Hospital. e205 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo and Video Essay FIG. 2. OCT demonstrating the normal retinal nerve fiber layer in the right eye and left eye. On neuro-ophthalmic examination, her visual acuity was 20/20 in both eyes. There was no relative afferent pupillary defect (RAPD) or anisocoria. Ishihara color plates were correctly identified in 7 of 14 plates OD and 14 of 14 plates in the left eye (OS). Automated perimetry (automated visual field 24-2) showed paracentral FIG. 3. Spectral-domain optical coherence tomography of the macula demonstrating thinning of the large area of the macular in the right eye and a normal-appearing macula in the left eye. The thinning of inner nuclear layer (indicated by the arrows) was present in a large area of the macula in the right eye. e206 Scott et al: J Neuro-Ophthalmol 2021; 41: e205-e208 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo and Video Essay depression OD and nonspecific scatter OS (Fig. 1). Motility, external examination, intraocular pressure, and slit-lamp examinations were normal in both eyes. Laboratory testing for vitamin A, B9 (folate), and B12 were normal. Serum erythrocyte sedimentation rate, C-reactive protein, and complete blood count were normal. Magnetic resonance scan of the head and orbit with gadolinium was normal. Optical coherence tomography (OCT) showed a normal peripapillary retinal nerve fiber layer in both eyes (Fig. 2). OCT of the OD macula, however, showed a decrease in central macular thickness with retinal thinning (Fig. 3). A large area of the central macula was noted to have thinning and an indistinguishable inner nuclear layer (INL). A diagnosis of resolved paracentral acute middle maculopathy (PAMM) was made. The OS was normal. OD maculopathy was confirmed by multifocal electroretinography (mfERG), which showed foveal depressions OD (Fig. 4). Serial follow-up showed no change in the examination over time. Differentiating retinal from optic nerve etiologies in patients with acute, unilateral, central loss of vision with a normal fundus can be difficult. The differential diagnosis for an acute central scotoma includes maculopathy and retrobulbar optic neuropathy. The clinical presentation of maculopathy and optic neuropathy can overlap, and both conditions can present in patients with a normal fundus. Several clinical features can suggest a retinal rather than an optic nerve etiology to unexplained visual loss. These features include paracentral or ring scotoma and lack of a significant RAPD. In this case, ophthalmoscopic examination, OCT of the optic nerve (peripapillary retinal nerve fiber layer), fundus fluorescein angiography, and flash ERG were all normal. Flash ERG, however, may be normal in focal or small retinal lesions (1). By contrast, mfERG measures focal retinal responses in the central retina. In addition, spectral domain (SD) OCT of macula can show thinning of inner, middle, and/or outer retina (2). Our patient’s color deficit was due to a large area of central macula ischemia. When PAMM was first described in 2013, it was believed to be a variant of acute macular neuroretinopathy and has since been recognized as a distinct entity (3). PAMM is associated with ischemia of the intermediate and deep capillary plexus. Acute macular neuroretinopathy is associated with ischemia of deep capillary plexus. Most patients FIG. 4. Multifocal ERG demonstrating reduced amplitude centrally in the right eye and normal amplitude throughout in the left eye. Scott et al: J Neuro-Ophthalmol 2021; 41: e205-e208 e207 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo and Video Essay with these retinal ischemia signs have retinal vascular disease or systemic vasculopathic risk factors. Recently, there have been a few case reports describing PAMM in eyes with optic nerve disorders including meningitis-associated optic neuritis (4) and idiopathic intracranial hypertension–associated optic disc edema (5). Inflammatory occlusion in the former (4) and perfusion occlusion from compression in the later case (5) were the suggested underlying pathophysiology that predisposed to microvascular retinal ischemia. Our patient had retinal ischemia without concurrent optic nerve disease. PAMM is more often than not because of an underlying retinal pathology rather than optic nerve disease. Clinicians should consider mfERG and/or OCT macula in patients with unexplained central visual dysfunction. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: R. A. Scott, N. Bhat, S. H. Bindiganavile, and H. K. Li; b. Acquisition of data: R. A. Scott, N. Bhat, S. H. Bindiganavile, and H. K. Li; c. Analysis and interpretation of data: R. A. Scott, N. Bhat, S. H. Bindiganavile, and H. K. Li. Category 2: a. Drafting the manuscript: R. A. Scott, e208 N. Bhat, S. H. Bindiganavile, and H. K. Li; b. Revising it for intellectual content: R. A. Scott, N. Bhat, S. H. Bindiganavile, and H. K. Li. Category 3: a. Final approval of the completed manuscript: R. A. Scott, N. Bhat, S. H. Bindiganavile, and H. K. Li. REFERENCES 1. Young B, Eggenberger E, Kaufman D. Current electrophysiology in ophthalmology: a review. Curr Opin Ophthalmol. 2012;23:497–505. 2. Sarraf D, Rahimy E, Fawzi AA, et al. Paracentral acute middle maculopathy: a new variant of acute macular neuroretinopathy associated with retinal capillary ischemia. JAMA Ophthalmol. 2013;131:1275–1287. 3. Chen X, Rahimy E, Sergott RC, et al. Spectrum of retinal vascular diseases associated with paracentral acute middle maculopathy. Am J Ophthalmol. 2015;160:26–34.e1. 4. Zhao Z, Faith P, Pakzad-Vaezi K, et al. Paracentral acute middle maculopathy associated with bilateral optic disk swelling and meningitis. Retin Cases Brief Rep. 2017;14:157–162. 5. Denny MR, Kalevar A, Chen JJ, Johnson RN. Paracentral acute middle maculopathy associated with idiopathic intracranial hypertension. Retin Cases Brief Rep. 2019;0:1–3. Scott et al: J Neuro-Ophthalmol 2021; 41: e205-e208 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.