Re: Bhatti et al.: Microcystic macular edema in optic nerve glioma (Ophthalmology. 2020;127:930)

Abstract

Bhatti et al1Bhatti M.T. Mansukhani S.A. Chen J.J. Microcystic macular edema in optic nerve glioma.Ophthalmology. 2020; 127: 930Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar present images from a patient with inner nuclear layer cysts visible on OCT in the setting of an optic nerve glioma.1Bhatti M.T. Mansukhani S.A. Chen J.J. Microcystic macular edema in optic nerve glioma.Ophthalmology. 2020; 127: 930Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar They attribute these to the effect of vitreous traction on Müller cell footplates (forming the inner limiting membrane) after degeneration of the ganglion cells and retinal nerve fiber layer (RNFL). This is one hypothesis, but it should be noted that another mechanism postulated in the literature is that these cysts represent retrograde trans-synaptic degeneration (presumably of bipolar cells) after the loss of ganglion cells.2Lujan B.J. Horton J.C. Microcysts in the inner nuclear layer from optic atrophy are caused by retrograde trans-synaptic degeneration combined with vitreous traction on the retinal surface.Brain. 2013; 136e260Crossref PubMed Scopus (33) Google Scholar,3Abegg M. Dysli M. Wolf S. et al.Microcystic macular edema: retrograde maculopathy caused by optic neuropathy.Ophthalmology. 2014; 121: 142-149Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar It is possible that both mechanisms are contributory.2Lujan B.J. Horton J.C. Microcysts in the inner nuclear layer from optic atrophy are caused by retrograde trans-synaptic degeneration combined with vitreous traction on the retinal surface.Brain. 2013; 136e260Crossref PubMed Scopus (33) Google Scholar We have reported previously that patients with visual loss associated with silicone oil (after retinal detachment surgery) exhibit loss of RNFL and ganglion cells, and also demonstrate the same microcystic change after some years.4Shalchi Z. Mahroo O.A. Shunmugam M. et al.Spectral domain optical coherence tomography findings in long-term silicone oil-related visual loss.Retina. 2015; 35: 555-563Crossref PubMed Scopus (29) Google Scholar The vitreous traction hypothesis is less likely in these patients because they lack a vitreous, although it remains possible that a tractional element exists. The retrograde trans-synaptic degeneration hypothesis is plausible, and has been demonstrated at other levels in the visual pathway, such as RNFL thinning secondary to occipital cortex lesions.5Jindahra P. Petrie A. Plant G.T. Retrograde trans-synaptic retinal ganglion cell loss identified by optical coherence tomography.Brain. 2009; 132: 628-634Crossref PubMed Scopus (165) Google Scholar We agree with Bhatti et al that the term “microcystic macular edema” is a misnomer and we prefer the term “retrograde maculopathy,”3Abegg M. Dysli M. Wolf S. et al.Microcystic macular edema: retrograde maculopathy caused by optic neuropathy.Ophthalmology. 2014; 121: 142-149Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar which is neutral as to the precise mechanism, but emphasizes the primary role of ganglion cell loss. Microcystic Macular Edema in Optic Nerve GliomaOphthalmologyVol. 127Issue 7PreviewA 42-year-old woman with neurofibromatosis 1 and bilateral (left larger than right) optic nerve gliomas was seen for an annual ophthalmic examination. Visual acuity was 20/20 right eye and 20/25 left eye with a left relative afferent pupillary defect. OCT demonstrated hyporeflective lesions in the inner left retina termed “microcystic macular edema”; however, this term is a misnomer. The OCT changes represent cystic spaces in the inner nuclear layer resulting from vitreous traction on the Müller footplates preventing the retina from collapsing in the setting of ganglion cell loss from any optic neuropathy. Full-Text PDF