Abstract
Purpose: To investigate on the morphology of the macular inner (IR) and outer (OR) layers in multiple sclerosis (MS) patients with and without history of optic neuritis (ON), followed by good or poor recovery of best corrected visual acuity (BCVA).Methods: Thirty-five normal control subjects and 93 relapsing remitting MS patients were enrolled. Of this, 40 MS patients without ON (MS-noON, 40 eyes), 27 with history of ON and good BCVA recovery (MS-ON-G, 27 eyes), and 26 with history of ON and poor BCVA recovery (MS-ON-P, 26 eyes) were studied. Controls and MS patients underwent an extensive ophthalmological examination including spectral-domain optical coherence tomography evaluating in 3 localized macular areas (0–1 mm, Area 1; 1–3 mm, Area 2; 3- 6 mm, Area 3), volumes (MV), and thicknesses (MT) of the whole retina (WR), further segmented in IR and OR. The differences of MV and MT between the groups were tested by ANOVA. In the MS-ON-P group, the correlations between MV and MT and BCVA were evaluated by Pearson's test.Results: When compared to controls, the MS-noON group showed not significantly (p > 0.01) different MVs, whereas MTs were significantly (p < 0.01) reduced in the evaluation of WR and IR. In the MS-ON-G group, a significant (p < 0.01) reduction of WR and IR MVs and MTs was found in Areas 2 and 3; OR MVs and MTs were similar (p > 0.01) to controls. In the MS-ON-P group a significant (p < 0.01) reduction of WR, IR, and OR MVs and MTs was detected in all areas; the BCVA reduction was significantly (p < 0.01) correlated with WR and IR MVs and MTs.Conclusions: In MS without history of ON or when ON is followed by a good BCVA recovery, the neurodegenerative process is limited to IR macular layers; in the presence of ON, with a poor BCVA recovery, a morphological impairment of both IR and OR macular layers occurs.
Highlights
The effects of this neurodegenerative process on the neuroretinal structure can be objectively studied by Optical Coherence Tomography (OCT), that usually detects a reduction of retinal nerve fibers layer (RNFL) thickness [3,4,5]
inner retinal (IR) abnormalities [thinning of retinal ganglion cells (RGCs)/inner plexiform layer (GC/IPL) and thinning/thickening of the inner nuclear layer (INL) and reduced whole macular volume [4, 7,8,9,10]] are known to occur in multiple sclerosis (MS) [11,12,13] with and without previous optic neuritis, whereas data about morphological macular OR changes are controversial [7, 12, 14,15,16,17,18,19]. All this suggests that the MS neurodegenerative process involves the macular layers and mainly the ganglionic elements located in the IR
In the Multiple Sclerosis patients without Optic Neuritis (MS-noON) group, the values of whole retina (WR), IR, and OR macular volume (MV) detected in Areas 1, 2, and 3 and in the combined Area 1+2+3 were not significantly (p > 0.01) reduced with respect to controls
Summary
In about 20–25% of multiple sclerosis (MS) patients, the pathology can onset with retrobulbar optic neuritis (ON) [1], that is followed by a secondary neurodegenerative process, reflecting retrograde degeneration that involves retinal ganglion cells (RGCs) and their axons [2].The effects of this neurodegenerative process on the neuroretinal structure can be objectively studied by Optical Coherence Tomography (OCT), that usually detects a reduction of retinal nerve fibers layer (RNFL) thickness [3,4,5].An interesting and widely discussed topic in MS with or without ON has been to investigate whether the retinal elements of the macular region are morphologically impaired.Currently, with the innovative Spectral domain-OCT (SdOCT) technique, it is possible to selectively segment the macular volume (MV) and thickness (MT) of the outer (OR) and inner retinal (IR) layers [6]. IR abnormalities [thinning of RGCs/inner plexiform layer (GC/IPL) and thinning/thickening of the inner nuclear layer (INL) and reduced whole macular volume [4, 7,8,9,10]] are known to occur in MS [11,12,13] with and without previous optic neuritis, whereas data about morphological macular OR changes are controversial [7, 12, 14,15,16,17,18,19]
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