Macular microhole and foveal red spot syndrome: a critical review of the literature

Abstract

Purpose: The purpose of this article is to review the literature on nomenclature, natural history, clinical features, diagnosis, management, and prognosis of both macular microhole (MMH) and foveal red spot syndrome (FRS).

Methods: A PubMed primary literature search (February 1, 2020) utilizing the terms macular microhole, foveal red spot syndrome, and outer retinal hole was conducted. All chosen articles were case reports or case series. Articles qualified for inclusion if they documented symptoms, imaging findings, or followed patients longitudinally.

Results: A total of 14 studies from 1988 to 2019 that evaluated either MMH, FRS, or both were included in the review. No comparative study between the two defects was found. Studies often used the terms FRS and MMH interchangeably to reference both partial- and full-thickness lesions of the macula. Spectral-domain optical coherence tomography (SD-OCT) was most frequently able to identify these lesions and revealed an absence of all neural retinal layers from the inner limiting membrane (ILM) to the retinal pigment epithelium (RPE) in the full-thickness lesions while the partial-thickness lesions most often involved the photoreceptor layer (PRL) and less frequently the external limiting membrane (ELM). OCT revealed that vitreomacular traction (VMT) was involved in the natural history of both FRS and MMH for a significant subset of patients.

Conclusion: The terms MMH and FRS have been used interchangeably in the literature. Advances in OCT have revealed that MMHs and FRSs are distinct but sometimes overlapping entities. We suggest that MMH and FRS are similar entities defined as one or more sharply defined lesions in the fovea of the eye < 150 μm in size. MMHs are a full-thickness defect of the entire neuroretina at the center of the foveola while FRSs are partial-thickness lesions. Current literature suggests that there may be subtle differences in the pathogenesis, clinical features, and diagnosis between MMH and FRS; however, prognosis and management for both are favorable. Lastly, we suggest that the terms outer lamellar macular microholes and full-thickness macular microholes may be the more appropriate terminologies to refer to FRS and MMH, respectively.

Keywords: Foveal red spot; Foveal red spot syndrome; Full thickness macular microhole; Macular hole; Macular microhole; Outer foveal defect; Outer lamellar macular microhole.