A case documenting distinct natural history of multizonal outer retinopathy and retinal pigment epitheliopathy (MORR) with longitudinal multi-modal documentation of progression

Abstract

Purpose: To describe the clinical and imaging characteristics of the acute progressive phase of a recently proposed clinical entity, Multizonal Outer Retinopathy and Retinal Pigment Epitheliopathy (MORR), a variant of Acute Zonal Occult Outer Retinopathy (AZOOR).

Methods: Single observational case report.

Results: We present the case of a 49-year-old myopic female with progressive outer retinopathy most consistent with a diagnosis of MORR. Through multimodal imaging and longitudinal follow-up, we delineate the clinical course and imaging findings of asymmetrical episodic progressive centrifugal extension of retinal pigment epithelial disturbance in both eyes, highlighting the features of an acute progressive episode not previously described.

Conclusions: Clinicians should be aware of the active clinical and multimodal imaging features of MORR and its distinction from other outer retinopathies due to its sight-threatening distinct clinical course, bilateral involvement with peripapillary lesions, and episodic progression into the macula. Additionally, we describe a "grass-fire" and "spot-fire" progression pattern during acute exacerbation, highlighting the need for vigilant monitoring and early intervention in MORR.

Keywords: AAOR; AZOOR; MORR; Outer retinopathy; White dot syndromes.

Fig. 1

Left fundus appearance at presentation (July 2021) – an area of pigment disturbance can be seen encircling the optic disc and extending inferiorly between the nasal and temporal inferior arcades.

Fig. 2a

Left fundus appearance 16 months after presentation (November 2022) – significant progression of fundus changes superiorly in a fan-like appearance.

Fig. 2b

Right fundus appearance 16 months after presentation (Nov 2022) – early changes at the temporal aspect of the optic disc can be seen.

Fig. 3

Fundus Autofluorescence of the left eye at follow-up (Nov 2022) demonstrating hypo- and hyper-autofluorescence with centrifugal progression along the vascular arcades.

Fig. 4

Close-up OCT B scan of the left eye demonstrating RPE and outer retinal disruption with irregularity and focal atrophy (red arrows). The yellow arrowhead indicates elevation and outer retinal hyperreflectivity corresponding to the yellow-grey line during acute progression; note the involvement of the ellipsoid and interdigitation layers and attenuation of the underlying RPE, but preservation of the overlying external limiting membrane and outer nuclear layer. The subfoveal choroidal thickness was 400 μm. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 5

Fluorescein Angiogram at same time point as Fig. 3, above, in late phase demonstrating bright speckled staining but no leakage within the lesion or optic disc.

Fig. 6

Multimodal image of acute progression, with a "grass-fire" spread into the macula (red arrowheads) including a new "spot-fire" satellite lesion in the inferior macula developing and then coalesceing with the larger lesion (green arrowheads), showing hyperautofluorescent advancing edge seen as grey-white band on fundus images. 6A-C – Color fundus photos of the left eye demonstrating acute progression of the peripapillary scalloped area of RPE disturbance inferotemporal to and radiating from the optic disc in a centrifugal fan-like pattern. The active "leading edge" of the new RPE lesion is marked by a yellow-grey band, seen best in 6B (red arrow). 6D-F – Fundus autofluorescence of the left eye demonstrating widespread hyper- and hypo-autofluorescence with bright hyperautofluorence at the advancing edge (red arrow in 6E), then meeting with the satellite lesion in the inferior macula (green arrow in 6E and then 6F) 6G-I – Ocular Coherence Tomography of the left eye demonstrating correlation of the band of leading edge of RPE lesion on infra-red imaging with hyper-reflectance and elevation of the outer retinal layers (ellipsoid and interdigitation zone) and attenuation of the underlying RPE. The overlying outer nuclear layer and external limiting membrane appear intact. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)