Retinal inner nuclear layer volume reflects inflammatory disease activity in multiple sclerosis; a longitudinal OCT study

Inner nuclear layer; Multiple sclerosis; Optical coherence tomography Capa nuclear interna; Esclerosis múltiple; Tomografía de coherencia óptica Capa nuclear interior; Esclerosi múltiple; Tomografia de coherència òptica Background: The association of peripapillary retinal nerve fibre layer (pRNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness with neurodegeneration in multiple sclerosis (MS) is well established. The relationship of the adjoining inner nuclear layer (INL) with inflammatory disease activity is less well understood. Objective: The objective of this paper is to investigate the relationship of INL volume changes with inflammatory disease activity in MS. Methods In this longitudinal, multi-centre study, optical coherence tomography (OCT) and clinical data (disability status, relapses and MS optic neuritis (MSON)) were collected in 785 patients with MS (68.3% female) and 92 healthy controls (63.4% female) from 11 MS centres between 2010 and 2017 and pooled retrospectively. Data on pRNFL, GCIPL and INL were obtained at each centre. Results: There was a significant increase in INL volume in eyes with new MSON during the study (N=61/1562, β=0.01mm3, p