Current understanding of the epidemiologic and clinical characteristics of optic neuritis

In Vivo Corneal Confocal Microscopy for Detecting Corneal Nerve Fiber Changes in Patients with Different Types of Optic Neuritis: A Cross-Sectional Study

PURPOSE

Optic neuritis (ON), a demyelinating disease of the central nervous system, is often a precursor manifestation of neuromyelitis optica spectrum disorders (NMOSD) or multiple sclerosis (MS). Reduced corneal nerve fiber counts have been found in patients with NMOSD or MS. This study aimed to observe and compare the corneal subbasal nerve plexus in patients with three types of ON and controls without ON using in vivo corneal confocal microscopy (IVCM).

METHODS

Data were analyzed for 77 eyes of 48 patients with ON, grouped according to seropositivity for anti-aquaporin-4 IgG, myelin oligodendrocyte glycoprotein antibody, or no seropositivity, and 35 healthy eyes in the control group. Corneal parameters were quantified based on IVCM images. Visual function indicators were recorded, following which their correlations with IVCM parameters were analyzed.

RESULTS

Significant differences in IVCM parameters were detected among the different groups. Reductions in corneal nerve fiber counts were negatively correlated with visual acuity. Corneal nerve fibers were significantly more damaged in the affected eye than in the unaffected eye in patients with ON.

CONCLUSION

IVCM revealed corneal nerve fiber loss of varying degrees, depending on the type of ON. This indicates that, although ON primarily affects the central nervous system, peripheral nerves, such as the trigeminal nerve, which innervates the corneal subbasal nerve plexus may also be damaged in affected patients.

Can volumetric analysis of the brain help diagnose isolated optic neuritis?

Isolated optic neuritis is a single episode inflammatory optic neuropathy. This condition, which affects the optimal function of the optic nerve, is not associated with neurological or systemic diseases. Our study aimed to compare patients with isolated optic neuritis and normal healthy individuals in terms of the cerebrum, cerebellum and hippocampus volumes by using the "volBrain Online MRI Brain Volumetry System" program. Persons diagnosed with isolated optic neuritis (n = 16) and persons without any disease (n = 16) were included in the study. VolBrain was used to process the MRI data and, the findings were compared with Mann-Whitney U test. Values with a p-value <0.05 were considered statistically significant. The cerebrum white matter volumes in the total brain and in the right-left hemispheres of the brain were statistically significantly lower in the optic neuritis group (p = 0.029; p = 0.050; p = 0.029, respectively). In the segmental cerebellum analysis, the left side lobule VIIIB, the total and right-left side lobule IX volumes were statistically significantly higher (p = 0.022; p = 0.014; p = 0.029; p = 0.018, respectively). In total, lobule I-II volume was statistically significantly lower in the optic neuritis group (p = 0.046). In the segmental hippocampus analysis, the right side CA2-CA3, the total and right-left side SR-SL-SM volumes were statistically significantly lower in the optic neuritis group (p = 0.039; p = 0.050; p = 0.016, respectively). There are neurodegenerative changes in brain volume in patients with isolated optic neuritis. Although volBrain alone is not sufficient to diagnose isolated optic neuritis, it provides quantitative data that can be used as a complementary diagnostic method.

The 100 Most-Cited Articles on Optic Neuritis: Trends of Subtypes, Authorship, and Time

BACKGROUND

Optic neuritis (ON) is an optic nerve inflammation that may lead to different degrees of vision loss. In recent decades, ON research facilitated a better understanding of the disease and its subtypes. This bibliometric analysis aimed to detect the 100 most-cited medical articles related to ON in the last 50 years (1972-2021) and describe publication trends arising from the list.

METHODS

The Scopus database was used to locate and screen the 100 most influential ON papers based on the number of citations per article. Each entry was reviewed for the first author (name, gender, institution, and country), year of publication, journal, number of citations, ON subtype, and study design. The mean impact factor (IF) of each journal was calculated.

RESULTS

The median number of citations was 265 (range 182-2,396). Observational studies on neuromyelitis optica-associated ON were the most common (27%), and the most influential decade was 2002-2011 (54 papers). Seventy-nine percent of articles were published in neurology journals, and a positive correlation between the mean number of citations per article and the journal mean IF was observed ( r = 0.62, P < 0.001). Between 2009 and 2021, female authors led more ON studies (52%), and more publications originated outside the USA (68%), compared with previous years.

CONCLUSIONS

This analysis summarizes the impact and shifting trends of ON research in the last decades.

Update on glial antibody-mediated optic neuritis

Optic neuritis (ON) refers to inflammatory demyelinating lesions of the optic nerve, which can cause acute or subacute vision loss and is a major cause of vision loss in young adults. Much of our understanding of typical ON is from the Optic Neuritis Treatment Trial. Glial autoantibodies to aquaporin-4 immunoglobulin (AQP4-IgG) and myelin oligodendrocyte glycoprotein immunoglobulin (MOG-IgG) are recently established biomarkers of ON that have revolutionized our understanding of atypical ON. The detection of glial antibodies is helpful in the diagnosis, treatment, and follow-up of patients with different types of ON. AQP4-IgG and MOG-IgG screening is strongly recommended for patients with atypical ON. Research on the pathogenesis of NMOSD and MOGAD will promote the development and marketing of targeted immunotherapies. The application of new and efficient drugs, such as the selective complement C5 inhibitor, IL-6 receptor inhibitor, B cell-depleting agents, and drugs against other monoclonal antibodies, provides additional medical evidence. This review provides information on the diagnosis and management of glial antibody-mediated ON.

Memantine administration in patients with optic neuritis: a double blind randomized clinical trial

INTRODUCTION

As an inflammatory phenomenon, optic neuritis (ON) that causes demyelination in the optic nerve damages the retinal cells, and leads to visual impairment. Herein, we aimed to investigate the potential therapeutic effects of memantine on ON.

METHODS

In this double-blinded randomized clinical trial, participants with the first episode of acute ON meeting the inclusion criteria were enrolled and were randomly divided into memantine group (MG; N = 20) and placebo group (PG; N = 18). Patients of MG received memantine for 6 weeks. The thickness of the retinal nerve fiber layer (RNFL), visual evoked potential (VEP), and visual acuity (VA) was measured in both groups at baseline and 3-month follow-up.

RESULTS

Thirty-eight patients with ON were enrolled. In the follow-up, mean RNFL thickness of both groups significantly decreased in all quadrants (P < 0.001). Also, RNFL thickness of all but temporal quadrants were significantly higher in the MG than placebo. The reduction in RNFL thickness difference was insignificant between two groups in all but the inferior quadrant which was significantly lower in MG (P = 0.024). In follow-up, mean-to-peak of P100 of the affected eye were significantly lowered (P < 0.001). The changes in VEP were insignificant. Originally, the mean VA was 0.15 ± 0.08 and 0.17 ± 0.09 in MG and PG, respectively, but was improved significantly to 0.92 ± 0.06 and 0.91 ± 0.06 in MG and PG, respectively, in follow-up.

CONCLUSION

Memantine can reduce the RNFL thinning in three quadrants by blocking NMD receptors. However, visual acuity did not show a significant difference between the two groups.