Retinal nerve fiber layer thickness in multiple sclerosis with and without optic neuritis: a four-year follow-up study from Oman

Abstract

Background Multiple sclerosis (MS) is an autoimmune disease that attacks the central nervous system, with optic neuritis (ON) being a common early manifestation. Retinal nerve fiber layer (RNFL) thickness may be a biomarker of neuroaxonal damage in MS patients. We sought to evaluate changes in RNFL thickness over 4 years in Omani MS patients with or without ON in comparison to a healthy control group. Methods This retrospective case-control study involved 27 MS patients and 25 healthy controls. Optical coherence tomography was performed upon first diagnosis and at a four-year follow-up. Differences in mean RNFL thickness were calculated. Results A total of 51 eyes from the MS group and 50 eyes from the control group were evaluated. There was a significant reduction in mean RNFL thickness among MS patients with ON at follow-up (81.21 versus 72.14 μm; P = .003), whereas no significant RNFL thinning was observed among MS patients without ON. However, there was a significant reduction in RNFL thickness among MS patients compared to healthy controls (76.79 versus 93.72 μm; P = .009), regardless of ON presence/absence. Conclusions Axonal damage was seen in the optic nerves of Omani MS patients. Moreover, there was a significant reduction in RNFL thickness among MS patients with ON as the disease progressed; however, while there was evidence of RNFL thinning in MS patients without ON, this difference lacked statistical significance. Evaluation of RNFL thickness may represent a useful biomarker for monitoring disease progression in MS and its association with ON.

Retinal Glutamate Neurotransmission: From Physiology to Pathophysiological Mechanisms of Retinal Ganglion Cell Degeneration

“…In addition, retinal degeneration is also reported in other neurodegenerative diseases, traditionally affecting other CNS regions, such as multiple sclerosis (including in the absence of associated optic neuritis) [ 106 , 107 , 108 ], Alzheimer’s [ 109 , 110 ], and Parkinson’s [ 111 , 112 ], diseases, giving rise to the concept that the retina can serve as ‘diagnostic window into the brain’ and giving insight into neurodegenerative processes occurring elsewhere [ 113 ]. In humans, thinning of the retinal nerve fibre layer (RNFL) containing RGC axons has been used as a diagnostic indicator of retinal, and particularly RGC, degeneration (as well as testing of neuroprotective therapies) since this region is particularly vulnerable in glaucoma [ 114 ], diabetic retinopathy [ 115 ], retinal ischemia [ 116 ] and in optic neuritis [ 104 ] as well as in multiple sclerosis [ 117 ], Alzheimer’s [ 118 , 119 ] and Parkinson’s [ 120 , 121 ] diseases.…”

Peripapillary hyperreflective ovoid mass‐like structures: Multimodal imaging—A review

“…As the optic nerve is an extension of the CNS, previous studies have hypothesized reduced RNFL thickness may be a biomarker for axonal loss in the CNS even in the absence of clinical optic neuritis 63,64 . However, more recent cross‐sectional and longitudinal studies showed no statistically significant difference in RNFL thinning in MS patients without a prior history of optic neuritis as compared to controls 65,66 . Although histopathology of human optic neuritis is lacking, there is evidence from a guinea pig model of autoimmune optic neuritis demonstrating swollen axons displaced into the peripapillary retinal tissue forming an S‐shaped bulge resembling PHOMS 16 .…”

Longitudinal Optical Coherence Tomography Measurement of Retinal Ganglion Cell and Nerve Fiber Layer to Assess Benign Course in Multiple Sclerosis

“…In the present study, the rates of RNFL and GCL-IPL thinning in non-ON BMS were −0.20 ± 0.27 and −0.19 ± 0.15 μm/year, mean ± SE, respectively, in agreement with results from earlier extrapolated rates for RNFL and GCL-IPL, where thickness loss was −0.11 ± 0.27 and −0.24 ± 0.24 μm/year, respectively [ 20 ]. The earlier study also reported a thinning rate of 0.54 ± 0.24 μm/year for RNFL in RR-MS; in other studies, the reported rate of loss of RNFL thickness in MS differed from about 0.9 µm/year [ 38 ] to 2.4 µm/year [ 39 ].…”