Role of optical coherence tomography in determining specific diagnostic pattern of retinal nerve fiber layer involvement in various central nervous system demyelinating diseases: An observational study

Abstract

AbstractAimsTo assess retinal nerve fiber layer thickness by optical coherence tomography (OCT) in various central nervous system demyelinating diseases.Methods and MaterialA total of 40 patients were selected. There were 8 patients of multiple sclerosis, 12 patients of neuromyelitis optica spectrum disorders (NMOSD), 9 patients of optic neuritis, and 11 patients of longitudinally extensive transverse myelitis (LETM). The fast retinal nerve fiber layer (RNFL) thickness protocol was used to compute the overall average RNFL thickness for each eye. Average RNFL thickness for 360° around the optic disk, for the superior, nasal, inferior, and temporal quadrants around the optic disk as well as in the twelve 30° segments (with 3 o'clock position as nasal) were recorded.ResultsAverage RNFL thicknesses were lower in NMOSD group. Superior, inferior, and temporal quadrants are the preferentially affected while 8 o'clock position RNFL was the thinnest. MS involved 8 o'clock position and temporal quadrant. Of 9 o'clock position and temporal quadrant were the thinnest in LETM. In idiopathic optic neuritis, lowest RNFL value was recorded in the nasal quadrant. In 3 o'clock position, maximum thinning was noted in idiopathic ON. At 9 o'clock position, maximum thinning was seen in LETM patients.ConclusionsMost o'clock positions and superior, inferior, and temporal quadrants were affected in NMOSD. MS mainly involved 8 o’clock position and temporal quadrant. LETM preferentially affected 9 o’clock position and the temporal quadrant. Hence, observing the pattern of RNFL thinning with OCT in CNS demyelinating diseases can intimate the etiological cause. However, larger studies are needed further to confirm the same.