Infrared imaging and spectral-domain optical coherence tomography findings correlate with microperimetry in acute macular neuroretinopathy: a case report

[Acute macular neuroretinopathy: En face OCT description, case series]

Acute macular neuroretinopathy (AMN) is a rare disease characterized by involvement of the outer retinal layers of the macula. The diagnosis of AMN is based on multimodal imaging, combining infrared reflectance (IR) imaging and optical coherence tomography with B-scan analysis (OCT-B). The en face OCT is a tomographic image processing technique, integrating data from entire A-scans to create a frontal retinal image of the desired area. Structural en face OCT imaging appears to be effective in delineating AMN lesions, using segmentation between the outer plexiform line and the ellipsoid line. In the future, analysis of the various modalities of a single OCT acquisition may be sufficient to diagnose AMN.

Bilateral Acute Macular Neuroretinopathy in a Young Patient: Imaging and Visual Field during Two-Year-Follow-Up

Acute macular neuroretinopathy (AMN) is a rare disorder. We report a case of bilateral AMN in a young female patient, without any risk factors. She referred a positive scotoma in both eyes after flu-like symptoms. Fundus examination revealed parafoveal dark-reddish oval lesions in both eyes. Therefore, we performed visual field, optical coherence tomography (OCT), fluorescein angiography (FA) and indocyanine green angiography (ICG) at baseline and several times during the two years of follow-up. The infrared (IR) imaging showed one rounded hyporeflective lesion in the left eye and two similar lesions in the right eye. The OCT demonstrated the characteristic alterations in the outer retina. The visual field also demonstrated scotomas corresponding with these lesions. The OCT and IR features disappeared at the end of the follow-up except for the left eye, which continued to have hyperreflective spots in the outer plexiform layer. The patient complained about a residual scotoma only in the left eye after two years. Our case shows a difference in disease progression in the two eyes of the same patient, suggesting that several mechanisms can be implicated in the pathology of AMN.

An Atypical Presentation of Acute Macular Neuroretinopathy after Non-Ocular Trauma

Purpose

Acute macular neuroretinopathy (AMN) is a rare clinical entity with an uncertain etiology. We report an atypical case presenting with retinal hemorrhages (RH) and cotton-wool spots (CWS) following non-ocular trauma.

Observations

A 49-year-old male presented with an acute onset of a paracentral scotoma in his left eye, immediately following a motor vehicle accident 1 day prior. Fundus findings revealed a unilateral nasal petalloid perifoveal lesion with the tip pointing toward the fovea associated with CWS and RH. Optical coherence tomography demonstrated disruption of the ellipsoid zone. Symptoms and exam findings improved at 2-week follow-up without any intervention, consistent with the natural history of the disease process.

Conclusion

We report a rare case of AMN following non-ocular trauma with the unique fundus findings of CWS and RH. This presentation supports the role of ischemia in the retinal deep capillary plexus, of which trauma contributed to the pathophysiological process.

Summary

AMN is a rare condition whose pathophysiological process remains speculative. We report an atypical case of AMN, which supports the role of trauma in the pathophysiology of deep retinal capillary plexus compromise.

[Multimodal imaging in the diagnosis of acute macular neuroretinopathy]

INTRODUCTION

Acute macular neuroretinopathy is a retinal disease, usually presenting with a "normal fundus". Thus, this condition can be mistaken for optic neuropathy. Herein we present five clinical cases of patients affected with acute macular neuroretinopathy; one of them is a retrospective diagnosis while the others were diagnosed on initial examination. In the five cases, multimodal imaging with infrared photography and OCT helped to establish the diagnosis.

MATERIAL AND METHODS

Retrospective study of five clinical cases. Initial and final best visual acuities as well as infrared and OCT imaging were collected for all patients.

RESULTS

All patients initially reported a visual disturbance associated with a more or less severe decrease in visual acuity. Infrared imaging showed a dark, perifoveolar appearance of the lesions. In all cases, OCT images showed thickening and hyperreflectivity of the outer plexiform layer, extending towards the outer retinal layers.

CONCLUSION

Acute macular neuroretinopathy is a clinical entity that has been long-described, which now benefits widely from new imaging technologies, allowing an earlier and more accurate diagnosis, but calling into question the actual name of this condition. The exact pathophysiology of the condition remains nonetheless incompletely elucidated.

Selective cone photoreceptor injury in acute macular neuroretinopathy

PURPOSE

To evaluate retinal structural and functional abnormalities in a patient with acute macular neuroretinopathy.

METHODS

An adaptive optics scanning light ophthalmoscope was used to image the photoreceptor mosaic and assess rod and cone structure. Spectral-domain optical coherence tomography was used to examine retinal lamination. Microperimetry was used to assess function across the macula.

RESULTS

Microperimetry showed reduced function of localized areas within retinal lesions corresponding to subjective scotomas. Spectral-domain optical coherence tomography imaging revealed attenuation of two outer retinal bands typically thought to reflect photoreceptor structure. Adaptive optics scanning light ophthalmoscope images of the photoreceptor mosaic revealed a heterogeneous presentation within these lesions. There were areas containing non-waveguiding cones and other areas of decreased cone density where the remaining rods had expanded to fill in the vacant space. Within these lesions, cone densities were shown to be significantly lower than eccentricity-matched areas of normal retina, as well as accepted histologic measurements. A 6-month follow-up revealed no change in rod or cone structure.

CONCLUSION

Imaging of acute macular neuroretinopathy using an adaptive optics scanning light ophthalmoscope shows a preferential disruption of cone photoreceptor structure within the region of decreased retinal sensitivity (as measured by microperimetry). Adaptive optics-based imaging tools provide a noninvasive way to assess photoreceptor structure at a level of detail that is not resolved by use of conventional spectral-domain optical coherence tomography or other clinical measures.

Increased macular choroidal blood flow velocity during systemic corticosteroid therapy in a patient with acute macular neuroretinopathy

Purpose

The precise mechanism causing outer retinal damage in acute macular neuroretinopathy (AMN) remains unclear. In this study, choroidal blood flow velocity was quantitatively evaluated using laser speckle flowgraphy (LSFG) in a patient with AMN who received systemic corticosteroid therapy.

Methods

Corticosteroids were systemically administrated across 4 months for an AMN patient. LSFG measurements were taken ten consecutive times before treatment and at 1 week and 1, 3, and 10 months after the onset of therapy. The square blur rate, a quantitative index of relative blood flow velocity, was calculated using LSFG in three regions: Square 1, the macular lesion with findings of severe multifocal electroretinography amplitude reduction, and Squares 2 and 3, funduscopically normal-appearing retinal areas with findings of moderate and mild multifocal electroretinography amplitude reduction, respectively.

Results

The AMN lesion gradually decreased after treatment and improved results were detected on the Amsler chart, as well as on optical coherence tomography and scanning laser ophthalmoscopy. When the changing rates of the macular flow were compared with the mean square blur rate level before treatment (100%), 14.6%, 24.5%, 12.9%, and 16.3% increases were detected in Square 1 (macular lesion) at 1 week and 1, 3, and 10 months after treatment, respectively. Similarly, in Square 2 (normal-appearing area next to the lesion), 12.6%, 18.6%, 6.7%, and 8.3% increases were also noted at 1 week and 1, 3, and 10 months after treatment, respectively. In Square 3 (normal-appearing area apart from the lesion), 16.0%, 15.1%, 19.1%, and 3.8% increases were measured at 1 week and 1, 3, and 10 months after treatment, respectively.

Conclusion

In a patient with AMN, choroidal blood flow velocity at the lesion site, which was examined with LSFG, sequentially increased during systemic corticosteroid therapy, together with improvement of visual function. The present findings suggest that choroidal circulation impairment relates to the pathogenesis of AMN, extending over a wider area in the posterior pole than the site of an AMN lesion per se.