Multizonal outer retinopathy and retinal pigment epitheliopathy (MORR) with a chronologically divergent presentation- a case report

TL;DR

This case report describes a rare eye disease called MORR, which causes uneven and complex vision loss in both eyes over time.

Contribution

The report highlights the unique, phase-shifted progression of MORR and its diagnostic and therapeutic challenges.

Findings

MORR shows chronologically divergent bilateral involvement with RPE and photoreceptor damage.

Multimodal imaging is essential for tracking MORR progression and differentiating it from other retinal diseases.

Immunomodulatory therapies may stabilize MORR in some cases, but no definitive treatment exists.

Abstract

Acute zonal occult outer retinopathy (AZOOR) is a rare inflammatory disease of the outer retina, often presented with subtle early findings. A specific subtype, termed Multizonal Outer Retinopathy and Retinal Pigment Epitheliopathy (MORR), is characterized by distinct progression pattern (Ramtohul et al. Retina 43:1890–1903, 2023) in multiple zones of the outer retina and retinal pigment epithelium. This case report aims to illustrate the chronologically divergent presentation, a phase-shifting disease progression and the complex clinical course of MORR, and to discuss the diagnostic challenges posed by its phase‑shifted timeline as well as potential therapeutic options.

A case of a 52-year-old female patient with initially unilateral, inactive posterior uveitis was retrospectively analyzed. Over thirteen years, progressive functional impairment developed in the fellow eye. Findings were assessed using multimodal imaging (Optical Coherence Tomography [OCT], Fundus Autofluorescence [FAF], Fluorescein and Indocyanine Green Angiography [FFA/ICGA]) and electrophysiological examinations (multifocal ERG, full-field ERG, EOG, VEP). Additional rheumatologic and neurologic assessments were conducted, and an infectious workup was performed.

The patient demonstrated chronologically divergent bilateral involvement with extensive damage to the retinal pigment epithelium (RPE) and photoreceptors. Fundus autofluorescence revealed a tri- to multizonal pattern in the better eye, while the fellow eye already exhibited diffuse atrophic areas devoid of any autofluorescence. Electrophysiological, the better eye showed selectively prolonged latencies on multifocal electroretinography (multifocal ERG) but preserved amplitudes, whereas the more severely affected eye displayed substantial functional loss. Despite various therapeutic interventions, including high-dose corticosteroids and immunosuppressive agents, progressive visual impairment ensued, driven by increasing macular involvement.

This case highlights the marked heterogeneity and diagnostic complexities of Multizonal Outer Retinopathy and Retinal Pigment Epitheliopathy (MORR), a newly recognized progressive variant of Acute Zonal Occult Outer Retinopathy (AZOOR). The disease course can present with chronologically divergent manifestations in both eyes. While initial stages may exhibit only subtle funduscopic changes, structural and functional deficits can progress rapidly, episodically and in a phase-shifted manner. Multimodal imaging is essential to delineate the disease trajectory and to distinguish MORR from diseases affecting outer retina. Currently, no definitive treatment is available; although immunomodulatory therapies may stabilize the condition in certain cases, their efficacy remains inconsistent. Consequently, early low-vision management and close interdisciplinary collaboration are of particular importance.

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