Primary retinal pathology in multiple sclerosis as detected by optical coherence tomography

Sir, We read the recent Brain publication by Saidha et al. (2011) with great interest. In their manuscript, the authors suggested that primary retinal pathology detectable by optical coherence tomography (OCT) defines a subset of patients with multiple sclerosis (Saidha et al ., 2011). This subgroup of patients, which they termed ‘macular thinning predominant phenotype’, was reported to exist in ∼10% of the entire multiple sclerosis cohort examined by spectral domain OCT (Cirrus) at the authors’ centres. The macular thinning predominant OCT phenotype was defined by a combination of average macular thickness below the 5th percentile, with ipsilateral normal average retinal nerve fibre layer (RNFL) thicknesses (between the 5th and 95th percentiles of RNFL values from the manufacturer's normative database), in one or both eyes, in the absence of a history of acute optic neuritis in affected eyes (Saidha et al ., 2011). Sixty-two per cent (31/50) of patients fulfilling the macular thinning predominant OCT criteria had a macular thickness below the 1st percentile. In addition, there was a remarkable male preponderance among patients with the macular thinning predominant phenotype (70% male versus 30% female), a difference that was even more pronounced (77.4% male versus 22.6% female) among those patients with very low macular thicknesses (<1st percentile). These in vivo findings are in line with a recent post-mortem analysis reporting retinal pathology in multiple sclerosis beyond damage to the RNFL and the ganglion cell layer (Green et al ., 2010). These data are intriguing in that they point to a novel concept of primary retinal damage in multiple sclerosis. They indicate that retinal pathology might not only develop as a consequence of inflammatory attacks to the anterior optic pathway causing …