['We wanted to investigate if retinal nerve fiber layer thickness (RNFLT) measured by optical coherence tomography (OCT) might be a good marker of acute and chronic changes in the afferent visual pathway following acute optic neuritis (ON).', 'We studied the relationship of optic nerve lesion length, optic nerve mean area, and RNFLT, quantified by OCT, with fMRI response to a visual paradigm in 40 patients with acute ON and 19 healthy controls in a prospective cohort study over a 6-month period.', 'The main finding was a significant correlation of optic nerve lesion length and mean area with fMRI response in affected eyes in the acute phase and between RNFLT and fMRI response in affected eyes after recovery.'] Does retinal atrophy correlate with fMRI response in patients with recovered optic neuritis?