Ophthalmology Dx: Stumped by Scotomas?

Slideshow

  • Figure 1. The patient’s bitemporal gray/black bean-shaped paracentral scotomas noted on Amsler grid.

  • Figure 2. Visual field testing (HVF 10-2) demonstrates bilateral scotomas corresponding closely to clinical symptoms and Amsler grid.

  • Figure 3. Optical coherence tomography (OCT) identifies focal abnormal hyperreflectance in the perifoveal zone involving the middle and outer retinal layers bilaterally. Associated near-infrared reflectance reveals petaloid lesions.

  • Figure 4. Fundus autofluorescence demonstrates nasal hyperautofluorescence nasal to the fovea (more apparent in right eye).

  • Figure 5. The patient’s fundus photos are significant for a subtle area of blunted reflectance nasal to the macula in both eyes.

A 24-year-old White woman presented to the Massachusetts Eye and Ear emergency department with headache and bilateral flashing black dots. Two days prior, she had developed a severe holocephalic headache exacerbated by movement and associated with photophobia, nausea, vomiting, and diarrhea. The following day she developed bilateral gray/black bean-shaped paracentral scotomas with shimmering dots inside as well as pain with eye movements. Her only ocular history was mild myopia, and she was otherwise healthy.

On examination, her visual acuity was 20/15 OD and 20/20 OS with normal color vision. On Amsler grid testing, she indicated bilateral scotomas (Figure 1), which were apparent on Humphrey Visual Field 10-2 perimetry (Figure 2). Fundoscopy was grossly normal. Magnetic resonance imaging (MRI) of the brain and orbits with and without contrast and lab work were unremarkable. Optical coherence tomography (OCT) of the macula revealed patchy abnormal hyperreflectance parafoveally involving the middle and outer retinal layers bilaterally, and associated near-infrared reflectance revealed perifoveal petaloid lesions (Figure 3). The nasal lesions were hyperautofluorescent on fundus autofluorescence (FAF) (Figure 4). Successive fundus photography revealed subtle areas of bilateral blunted foveal reflex nasal to the macula and wedge-shaped hyperpigmentation nasal to macula on the left (Figure 5).

Acute macular neuroretinopathy (AMN) is a rare condition that classically presents in young, healthy women as sudden onset uni- or bilateral paracentral scotomas with preserved or mildly decreased central visual acuity.1 The scotomas are usually noted by patients to appear...

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Acute macular neuroretinopathy (AMN) is a rare condition that classically presents in young, healthy women as sudden onset uni- or bilateral paracentral scotomas with preserved or mildly decreased central visual acuity.1 The scotomas are usually noted by patients to appear dark red-purple, wedge- or teardrop-shaped, and point toward the fovea.2 Unilateral and bilateral disease are similarly common (45% and 55%, respectively). AMN most often occurs in women in their 20s and 30s, and its onset has been associated with numerous factors including the use of oral contraceptives (50%), a preceding flu-like syndrome (44%), intravenous epinephrine administration (10%), migraines, caffeine intake, trauma, COVID-19 vaccination, post-partum hypotension, and intravenous contrast.3–5 While AMN’s etiology remains a topic under investigation, deep retinal capillary plexus ischemia is thought to be the most likely pathogenic mechanism.2 Our patient’s presentations are characteristic of this diagnosis.

The scotoma location and shape are distinguishing features of AMN, and visual field testing abnormalities often correspond closely to a patient’s Amsler grid depiction. Retinal lesions are usually not visible on fundoscopic examination but are typically apparent with spectral domain OCT (SD-OCT) and near-infrared reflectance imaging. With SD-OCT, lesions will appear hyperreflective at the outer plexiform layer (OPL) and outer nuclear layer (ONL) with ellipsoid zone (EZ) disruption.6 Near-infrared reflectance reveals the tear-drop lesions with close anatomic correlation to visual deficits. Fundus autofluorescence (FAF) is often normal but may display a hypo- or hyper-autofluorescent lesion.2 Fluorescein and indocyanine green angiography are usually normal. Ultimately, the diagnosis is made based on clinical presentation in conjunction with outer retinal changes on imaging. 

AMN’s clinical presentation can be similar to other retinopathies, including acute idiopathic blind spot enlargement (AIBSE) syndrome, acute retinal pigment epitheliitis (ARPE, or Krill disease), and multiple evanescent white dot syndrome (MEWDS); however, with SD-OCT and near-infrared reflectance imaging, the characteristic AMN lesions are recognizably distinguished. Optic neuritis is typically distinguished by the presence of pain with extraocular movements, optic nerve swelling, a relative afferent pupillary defect, decreased color vision, and contrast enhancement of the optic nerve on MRI imaging. AMN is most closely related to paracentral acute middle maculopathy (PAMM); however, PAMM is much more common, generally presents in middle-aged adults, and OCT hyperreflectivity occurs superficial to the OPL, corresponding to inner nuclear layer (INL) ischemia and atrophy.7 

There is currently no known treatment for AMN. While the scotomas are at least partially permanent in all cases, they may improve with time, and nearly all patients present with and maintain good vision. Follow-up recommendations are variable, but generally include retinal imaging to follow retina thinning over time, particularly of the ONL. 

This case was contributed by Matthew C. Johnson, BS, a medical student and predoctoral research fellow at Massachusetts Eye and Ear and Harvard Medical School, Boston.

The case was edited by Grayson W. Armstrong, MD, MPH, an instructor of ophthalmology at Massachusetts Eye and Ear and Harvard Medical School and Director of Ophthalmology Emergency Service.

References

1. Turbeville SD, Cowan LD, Gass JDM. Acute macular neuroretinopathy: a review of the literature. Surv Ophthalmol. 2003;48(1):1-11. doi:10.1016/S0039-6257(02)00398-3

2. Bhavsar KV, Lin S, Rahimy E, et al. Acute macular neuroretinopathy: A comprehensive review of the literature. Survey of Ophthalmology. 2016;61(5):538-565. doi:10.1016/j.survophthal.2016.03.003

3. Fawzi AA, Pappuru RR, Sarraf D, et al. Acute macular neuroretinopathy: long-term insights revealed by multimodal imaging. Retina. 2012;32(8):1500. doi:10.1097/IAE.0b013e318263d0c3

4. Munk MR, Jampol LM, Souza EC, et al. New associations of classic acute macular neuroretinopathy. Bri J Ophthalmol. 2016;100(3):389-394. doi:10.1136/bjophthalmol-2015-306845

5. Bøhler AD, Strøm ME, Sandvig KU, Moe MC, Jørstad ØK. Acute macular neuroretinopathy following COVID-19 vaccination. Eye. 2022;36(3):644-645. doi:10.1038/s41433-021-01610-1

6. Feigl B, Haas A. Optical coherence tomography (OCT) in acute macular neuroretinopathy. Acta Ophthalmol Scand. 2000;78(6):714-716. doi:10.1034/j.1600-0420.2000.078006714.x

7. Rahimy E, Sarraf D. Paracentral acute middle maculopathy spectral-domain optical coherence tomography feature of deep capillary ischemia. Curr Opin Ophthalmol. 2014;25(3):207. doi:10.1097/ICU.0000000000000045