Microcystic macular oedema in optic neuropathy: case series and literature review

Abstract

Cavitations in the inner nuclear layer associated with severe optic atrophy and loss of retinal ganglion cells have clinically been termed microcystic macular oedema (MME). We describe a case series of MME in patients of all ages but predominantly younger patients with a wide range of optic atrophies ranging from acute onset optic disc drusen associated ischemic optic neuropathy to slowly progressive disease as glaucoma. There were no physical distinctions between MME in different causes of optic atrophy suggesting a common causative mechanism. We reviewed the literature on MME and it appears that MME is associated with more severe visual loss, and is more common in hereditary optic neuropathies and neuromyelitis optica spectrum disease rather than in patients with optic atrophy secondary to multiple sclerosis and glaucoma. Three main causative mechanisms have been proposed, including increased vitreal traction on the macular as the ganglion cells are lost. Others have suggested that trans-synaptic loss of cells in the inner nuclear layer causes formation of empty spaces or cavities. Finally, some have hypothesized a disturbance in the fluid homeostasis of the inner retina as Müller cells are lost or their function is impaired. There are no known treatments of MME. In conclusion, MME seems to be a marker of severe optic nerve atrophy irrespective of the underlying cause.

Optical coherence tomography angiography in multiple sclerosis: A cross-sectional study

“…We propose that the reduction of retinal tissue, including the loss of GCC and RNFL found by SD-OCT, leads to hypoxia. This was confirmed by the findings of microcystic edema and thickening of the inner nuclear layer (INL), which seems to share an ischemic pathogenesis [41].…”

Optical Coherence Tomography in Multiple Sclerosis

“…50 INL MME has also been observed in other forms of severe optic neuropathy. 51,52 In the absence of MME, INL thinning has been reported in all subtypes of MS, including 13% of MS participants in one study. 45,53 Saidha et al reported a possible unique microstructural phenotype of reduction of the inner and outer nuclear layers, without significant GCL/IPL or pRNFL thinning.…”

Diagnostic ability of confocal near-infrared reflectance fundus imaging to detect retrograde microcystic maculopathy from chiasm compression. A comparative study with OCT findings

“…This high prevalence, if compared to other optic nerve diseases, may in part be explained by the severity of optic nerve damage in the population from which our sample was drawn. As shown by earlier studies, RMM is strongly correlated with visual loss severity [4,7,27]. In a study on optic neuritis, MMA was found in 6.3% of eyes of patients with multiple sclerosis, 21% with neuromyelitis optica spectrum disorder (NMOSD) and in 53.8% of eyes with chronic relapsing inflammatory optic neuropathy (the latter two associated with much worse visual outcome than multiple sclerosis) [7].…”