Characterizing retinal structure injury in African-Americans with multiple sclerosis

- Multiple Sclerosis is clinically more aggressive in African Americans.
- We used Optical Coherence Tomography to examine retinal layer axonal loss.
- Groups consisted of healthy African-Americans, Caucasians and those with MS.
- Race-by-disease effects were modeled using Generalized Estimating Equations.
- Retinal axonal loss is more severe in African-Americans than Caucasians with MS.

To examine retinal structure injury in African-Americans (AA) with Multiple Sclerosis (MS) compared to Caucasians (CA) with MS, we used spectral domain optical-coherence tomography (OCT) in this cross sectional study. The peripapillary retinal nerve fiber layer (pRNFL) and macular volume of 234 MS patients (149 CA; 85 AA) and 74 healthy controls (60 CA; 17 AA) were measured. Intra-retinal segmentation was performed to obtain retinal nerve fiber (RNFL), ganglion cell (GCL), inner plexiform (IPL), inner nuclear (INL), outer plexiform (OPL), outer nuclear (ONL), retinal pigment epithelium (RPE), and photoreceptor (PR) layer volumes. Study was approved by IRB, and informed consent obtained from all participants. We found that pRNFL was thicker in AA v. CA healthy controls (100.9 vs 97.00 μm, p=0.004). Compared to HC, MS patients demonstrated thinner pRNFL (p<0.0001), and lower TMV (p<0.001), macular RNFL (p<0.0001), GCL (p<0.0001), and IPL (p<0.0001). AAMS patients had thinner pRNFL (87.2 vs 90.0 μm, and lower TMV (8.2 vs 8.4 mm3, p=0.0001), RNFL (0.73 vs 0.79 mm3, p=0.0001), and GCL (0.94 vs 0.98 mm3, p=0.007) than CAMS patients. Sub-analysis of patients without history of AON showed thinner pRNFL (88.9 vs 93.1 µm) and TMV (8.2 vs. 8.5 mm3, p<0.0001) in AAMS compared to CAMS patients. In conclusion, this cross-sectional study provides evidence supporting greater retinal structure injury in AAMS compared to CAMS patients, irrespective of history of AON. Our findings are consistent with other studies demonstrating a more severe CNS tissue injury in AAMS patients.