Purpose: To evaluate the intermediate and outer retina of patients with multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) using OCT and multifocal electroretinography (mf-ERG). Methods: Patients with MS ( n = 30), NMOSD ( n = 30), and healthy controls ( n = 29) underwent visual field (VF), OCT, and mf-ERG testing. The eyes were distributed into 5 groups: MS with or without history of ON (MS+ON, MS–ON), NMOSD with or without ON (NMOSD+ON, NMOSD–ON), and controls. The thickness of the macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer, outer plexiform layer, outer nuclear layer, and photoreceptor layer was measured. mf-ERG P1 and N1 responses were registered and grouped in 3 sets of rings. The groups were compared using GEE models, and effect size (ES) calculated. Results: Compared to controls, GCL and IPL thickness was significantly smaller in MS+ON (both p < 0.01), MS–ON ( p < 0.01 and p = 0.015, respectively), NMOSD+ON (both p < 0.01) and NMOSD–ON ( p = 0.03 and p = 0.018, respectively). ES was >0.80. mRNFL was smaller in three of the above groups ( p < 0.01, p < 0.001, and p = 0.028; ES > 0.80) but not in MS–ON eyes ( p = 0.18). No significant difference was observed for the remaining layers. Compared to controls, P1 and N1 peak times were shorter in MS ( p -values in the range 0.049–0.002, ES < 0.50; and 0.049–0.010; ES < 0.50, respectively) but not in NMOSD. These abnormalities were strongly correlated with intermediate and outer retinal layer thickness. Conclusions: mf-ERG data suggest outer retinal abnormalities in MS, but not in NMOSD. Our results may help understand how the two conditions differ regarding retinal damage.

Avaliação morfológica e funcional da retina de pacientes com esclerose múltipla e espectro da neuromielite óptica usando os eletrorretinogramas de campo total e multifocal e a tomografia de coerência óptica

Purpose: To compare the visual evoked potentials (VEPs) of optic neuritis (ON) patients with multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and controls. To evaluate correlations between VEP and optical coherence tomography (OCT), contrast sensitivity (CS), and automated perimetry. Methods: Fifty-five eyes with ON from 29 patients (MS = 14 and NMOSD = 15) and 57 eyes from 29 controls were evaluated using VEP, automated perimetry, CS, and optical coherence tomography. Three groups were analyzed: 1) MS eyes with history of ON (ON-MS), 2) NMOSD eyes with ON (ON-NMOSD), and 3) healthy controls. Groups were compared and associations between the parameters were tested. Results: Compared to controls, ON-MS eyes showed significantly delayed N75 and P100 latencies when using a medium-sized stimulus (30 9 ), and delayed P100 latency when using a large stimulus (1.5°), but similar amplitudes. Compared to controls, ON-NMOSD eyes showed significantly lower N75/P100 amplitudes (both stimulus sizes) and P100/N135 amplitudes (with the 30 9 stimulus), but latencies did not differ, except for a delayed P100 latency with the 30 9 stimulus. When comparing the 2 ON groups using the 1.5°stimulus, there was significant delay in P100 latency in ON-MS eyes and a reduction in N75/P100 amplitude in ON-NMOSD eyes. Peripapillary retinal nerve fiber layer, macular inner retinal layers, and CS measurements were significantly smaller in ON patients than in controls. A strong correlation was found between VEP parameters and inner retinal layer thickness in ON-NMOSD eyes. Conclusions: ON-MS eyes had normal amplitude and delayed VEP latency, whereas ON-NMOSD eyes displayed reduced amplitude and preserved latency when elicited by checkerboard stimulus with large 1.5°checks. Under such conditions, VEP may help distinguish resolved MS-related ON from resolved NMOSD-related ON.