Retinal thickness in multiple sclerosis: evaluation with optical coherence tomography
Abstract
In various neurodegenerative diseases ocular manifestations are very common which can be examined and monitored in vivo by a novel imaging technique Optical Coherence Tomography (OCT). So this study was conducted to compare retinal nerve fiber layer (RNFL) thickness and ganglion cell complex (GCC) between multiple sclerosis (MS) patients and healthy individual by optical coherence tomography (OCT). For this study 40 eyes of twenty consecutive MS patients and 40 eyes of 20 age matched healthy controls were taken. Comprehensive standardized ophthalmic examinations included visual acuity, cycloplegic refraction, color vision and intraocular pressure. Optical coherence tomography was performed using 3D Topcon OCT; RNFL thickness and ganglion cell complex (GCC) was detected with the inbuild software. Mean values for the thickness of the peripapillary RNFL and ganglion cell complex (GCC) were calculated and compared between both groups. It was observed that the RNFL thickness in each quadrant and ganglion cell complex (GCC) in MS patients were all significantly decreased in comparison to healthy controls. So it can be concluded that OCT is a valuable research instrument for evaluation and monitoring MS progression by measurement of the retinal nerve fiber layer (RNFL) as purely axonal structure (indicative for axonal loss) and the macular ganglion cell complex (evidence of neuronalloss).
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Introduction
Pathology of central nervous system (CNS) has eye manifestations. They are due to retrograde and/or direct degeneration of the visual pathways, mostly related to a direct injury to the optic nerve, retinal ganglion cell layer and/or its surrounding cells.1 Histopathologic studies have reported retinal nerve fiber layer (RNFL) thinning in various neurodegenerative diseases.2
These ocular manifestations can be examined and monitored in vivo by a novel imaging technique Optical Coherence Tomography (OCT). OCT has revolutionized ophthalmology and it has recently become a vital tool for clinicians and researchers in neuro-ophthalmic practice. It is non-invasive, high resolution technique that provides in vivo cross-sectional images of tissues that resemble histological analysis. The image resolution (up to 5µm) allows us to search about axonal-neuronal integrity in the afferent visual pathway and is faster, more reproducible, precise and less dependent on patient compared to perimetry. It can detect CNS inflammatory and degenerative pathology, such as Multiple Sclerosis, at possibly subclinical stages. It has a potential of quantifying neuroaxonal loss in MS, and the increasing acceptance of the anterior visual pathway as a model to investigate this disease.
It was hypothesize that OCT imaging of the retina in patients with multiple sclerosis may provide a high-resolution, objective, noninvasive, and easily quantifiable in vivo biomarker of severity of disease and presence of optic neuritis.
Conclusion
Patients with a history of multiple sclerosis had RNFL thinning that was detectable on OCT. OCT is a valuable research instrument for evaluation and monitoring MS progression by measurement of the retinal nerve fiber layer as purely axonal structure (indicative for axonal loss) and the macular ganglion cell complex (evidence of neuronal loss).Future prospective investigations of multiple sclerosis-related retinal changes should consider these findings when following subjects longitudinally. More precise high resolution OCT scans may be able to diagnose systemic diseases much earlier, with high sensitivity and specificity through ocular manifestations.