LONGITUDINAL ANALYSIS OF RETINAL AND BRAIN ATROPHY IN MULTIPLE SCLEROSIS

Abstract

Purpose : Non-invasive quantification of retinal axonal and neuronal loss have been proposed as surrogate markers of axonal loss in multiple sclerosis (MS). We assessed their longitudinal relationship with measures of brain atrophy and disability.

Methods : Retinal nerve fiber layer (RNFL) thickness and total macular volume (TMV) were estimated in patients with MS (n=60) and age-matched, healthy controls (n=52) by optical coherence tomography (OCT) at baseline and 24-month follow-up. Brain volumes were quantified from cranial magnetic resonance imaging using NeuroQuant®. Neurological disability was assessed by means of the expanded disability status scale.

Results : In patients with MS compared to controls there was a significant reduction in RNFL (p<0.0001) and TMV (p=0.0004) at baseline. Specifically, RNFL was significantly reduced in the temporal-superior (p<0.0001), temporal (p<0.0001), temporal-inferior (p<0.0001), nasal-inferior (p=0.0005) and nasal-superior (p=0.001) aspects of the optic nerve. Patients with secondary progressive MS (SPMS) showed a greater reduction in RNFL (p=0.003) and TMV (P<0.0001) compared to patients with relapsing-remitting MS (RRMS). RNFL / TMV were significantly correlated (Pearson’s r) with grey matter (GM) (p=0.0003/p=0.0287), temporal lobe (TL) (p=0.0007/p=0.0287), thalamus (TH) (p=0.0001/p=0.0012), putamen (PU) (p<0.0001/p=0.0006) and whole brain (WB) (p= 0.0028/p=0.0206) volumes at baseline. At follow-up, there was a further significant reduction in temporal-inferior RNFL (p=0.009) and TMV (p=0.009). Patients with SPMS had significantly more advanced loss of RNFL (p=0.01) and TMV (p=0.02) compared to patients with RRMS. RNFL / TMV were significantly correlated with GM (p=0.0143/p=0.0449), TL (p=0.0141/p=0.0381), TH (p=0.0004/p=0.0019) PU (p<0.0001/p=0.0012) and WB (p=0.0015/p=0.0211) volume at follow-up. Patients with baseline TMV < 25^th percentile (n= 12) showed a further significant reduction at follow-up in GM (p=0.02), TL (p=0.03), caudate (p=0.009), TH (p=0.0003), PU (0.009) and WB (p=0.001) volume. There was no significant relationship between retinal measures and clinical disability at baseline or follow-up.

Conclusions : There is a strong longitudinal relationship between retinal and brain atrophy in MS which further underpins the viability of OCT as a surrogate measure of axonal loss.

This is a 2021 ARVO Annual Meeting abstract.