Microcystic Macular Edema Caused by Non-Glaucomatous Optic Atrophy: A Single-Center, Retrospective, Cohort Study in France

Optic Atrophy (OA) can be associated with the development of microcystic macular edema (MME) in the perifoveal retinal inner nuclear layer (INL). We aimed here to retrospectively determine the prevalence of MME in patients with non-glaucomatous OA in our tertiary ophthalmology department between 2015 and 2020. We then examined how MME affected the thicknesses of the different retinal layers and the differences in demographic and clinical characteristics between those patients who developed MME and those who did not. A total of 643 eyes (429 patients) were included (mean age 45.9 ± 17.8 years, 52% female). MME developed in 95 (15%) eyes and across all etiologies of OA except for toxic/nutritional causes, but the prevalence of MME varied between the different etiologies. The development of MME was associated with thinning of the ganglion cell layer (11.0 vs. 9.6 μm; p = 0.001) and the retinal nerve fiber layer (10.1 vs. 9.15 μm; p = 0.024), with INL thickening in the 3- and 6-mm diameter areas of the central fovea. Patients developing MME had significantly worse distance best-corrected visual acuity than those not developing MME (0.62 vs. 0.38 logMAR; p = 0.002). Overall, the presence of MME in OA cannot be used to guide the diagnostic work-up of OA.

Peripapillary fluid: Obvious and not so obvious!

Intraretinal or subretinal fluid in the peripapillary area can be clinically visualized in conditions such as peripapillary choroidal neovascularization, optic disc pit maculopathy, and optic nerve head tumors and granulomas. Optical coherence tomography (OCT) helps to visualize peripapillary fluid in many other chorioretinal conditions such as peripapillary pachychoroid syndrome, posterior uveitis, central retinal vein occlusion, malignant hypertension, hypotonic maculopathy as well as neuro-ophthalmological conditions such as glaucoma, microcystic macular edema and disc edema due papilledema, non-arteritic anterior ischemic optic neuropathy, neuroretinitis, and diabetic papillopathy. Often, the differential diagnosis of peripapillary fluid is a bit tricky and may lead to misdiagnosis and improper management. We describe a diagnostic algorithm for peripapillary fluid on OCT and outline the salient features and management of these conditions.

Clinical review of retinotopy

Two observations made 29 years apart are the cornerstones of this review on the contributions of Dr Gordon T. Plant to understanding pathology affecting the optic nerve. The first observation laid the anatomical basis in 1990 for the interpretation of optical coherence tomography (OCT) findings in 2009. Retinal OCT offers clinicians detailed in vivo structural imaging of individual retinal layers. This has led to novel observations which were impossible to make using ophthalmoscopy. The technique also helps to re-introduce the anatomically grounded concept of retinotopy to clinical practise. This review employs illustrations of the anatomical basis for retinotopy through detailed translational histological studies and multimodal brain-eye imaging studies. The paths of the prelaminar and postlaminar axons forming the optic nerve and their postsynaptic path from the dorsal lateral geniculate nucleus to the primary visual cortex in humans are described. With the mapped neuroanatomy in mind we use OCT-MRI pairings to discuss the patterns of neurodegeneration in eye and brain that are a consequence of the hard wired retinotopy: anterograde and retrograde axonal degeneration which can, within the visual system, propagate trans-synaptically. The technical advances of OCT and MRI for the first time enable us to trace axonal degeneration through the entire visual system at spectacular resolution. In conclusion, the neuroanatomical insights provided by the combination of OCT and MRI allows us to separate incidental findings from sinister pathology and provides new opportunities to tailor and monitor novel neuroprotective strategies.

Subclinical anterior optic pathway involvement in early multiple sclerosis and clinically isolated syndromes

Optical coherence tomography (OCT) is gaining increasing relevance in the assessment of patients with multiple sclerosis. Converging evidence point to the view that neuro-retinal changes, in eyes without acute optic neuritis, reflect inflammatory and neurodegenerative processes taking place throughout the CNS. The present study aims at exploring the usefulness of OCT as a marker of inflammation and disease burden in the earliest phases of the disease. Thus, a cohort of 150 consecutive patients underwent clinical, neurophysiological and brain MRI assessment as well as lumbar puncture as part of their diagnostic workup for a neurological episode suggestive of inflammatory CNS disorder; among those 32 patients had another previous misdiagnosed episode. For the present study, patients also received a visual pathway assessment (OCT, visual evoked potentials, visual acuity), measurement of CSF inflammatory markers (17 cytokines-chemokines, extracellular vesicles of myeloid origin), and dosage of plasma neurofilaments. Subclinical optic nerve involvement is frequently found in clinically isolated syndromes by visual evoked potentials (19.2%). OCT reveals ganglion cell layer asymmetries in 6.8% of patients; retinal fibre layer asymmetries, despite being more frequent (17.8%), display poor specificity. The presence of subclinical involvement is associated with a greater disease burden. Second, ganglion cell layer thinning reflects the severity of disease involvement even beyond the anterior optic pathway. In fact, the ganglion cell layer in eyes without evidence of subclinical optic involvement is correlated with Expanded Disability Status Scale, low contrast visual acuity, disease duration, brain lesion load, presence of gadolinium enhancing lesions, abnormalities along motor and somatosensory evoked potentials, and frequency of CSF-specific oligoclonal bands. Third, the inner nuclear layer thickens in a post-acute (1.1-3.7 months) phase after a relapse, and this phenomenon is counteracted by steroid treatment. Likewise, a longitudinal analysis on 65 patients shows that this swelling is transient and returns to normal values after 1 year follow-up. Notwithstanding, the clinical, MRI, serological and CSF markers of disease activity considered in the study are strictly associated with one another, but none of them are associated with the inner nuclear layer. Our findings challenge the current hypothesis that the inner nuclear layer is an acute phase marker of inflammatory activity. The present study suggests that instrumental evidence of subclinical optic nerve involvement is associated with a greater disease burden in clinically isolated syndrome. Neuro-retinal changes are present since the earliest phases of the disease and yield important information regarding the neurodegenerative and inflammatory processes occurring in the CNS.

Microcystic macular degeneration in autosomal hereditary optic neuropathies: A cross-sectional retrospective study

OBJECTIVE

Patients with autosomal optic neuropathies (AON) may develop microcystic macular degeneration (MMD), observed on retinal optical coherence tomography (OCT) examination. This study aimed to report the prevalence of MMD in AON patients and to assess the consequences of MMD on retinal architecture.

METHODS

Retrospective single-center study conducted between 2001 and 2018. Patients affected by AON secondary to OPA1 or WFS1 gene mutations were included. The following data were collected: visual acuity, macular volume, vitreomacular interface and presence or absence of MMD.

RESULTS

Forty-two subjects (34 OPA1, 8 WFS1) were included. MMD was found in 12 (29%) patients, i.e. 6 of the 8 WFS1 patients (75%) and 6 of the 34 OPA1 patients (17%). In cases with MMD, total retinal volume was greater (P=0.02) in accordance with thickening of the inner nuclear layer (P<0.001). WFS1 subjects had the highest total retinal volume (P=0.01), in relation to a thickening of the inner plexiform layer (P=0.02), inner nuclear layer (P<0.001) and outer plexiform layer (P=0.002). MMD was significantly associated with the WFS1 mutation (P<0.001). No significant association was found between the presence of vitreomacular adhesion and MMD.

CONCLUSION

MMD was found in 29% of patients affected by AON and was more frequent in cases with a WFS1 gene mutation. MMD appears to be related to primary ganglion cell degeneration and Müller cell dysfunction. The vitreomacular interface does not appear to play a role in the occurrence of MMD.