title: Retinal nerve fiber layer thickness, brain atrophy, and disability in multiple sclerosis patients.
abstract: OBJECTIVE
  To study the relationship between retinal nerve fiber layer (RNFL) thickness and brain atrophy using magnetic resonance imaging (MRI) with bicaudate ratio (BCR) in patients with multiple sclerosis (MS) with different levels of disease severity. We also assessed whether RNFL thickness correlated with Expanded Disability Status Scale (EDSS) score.
  
  
  METHODS
  The participants consisted of 88 patients with MS and 59 age- and sex-matched healthy control subjects. Eleven patients had clinically isolated syndrome (CIS), 68 patients had relapsing-remitting MS (RR-MS), and 9 patients had secondary progressive MS. Patients and controls were evaluated using optical coherence tomography (OCT, Cirrus) and scanning laser polarimetry with variable corneal compensation (GDx VCC). Patients underwent the same brain MRI scanning protocol. Disability was evaluated according to the EDSS. The BCR was calculated by dividing the minimum intercaudate distance by brain width along the same level.
  
  
  RESULTS
  The BCR was higher in patients with MS (0.12 ± 0.03) than in controls (0.08 ± 0.009) (P < 0.001). OCT average RNFL thickness in patients with MS was significantly lower (84.51 ± 14.27 μm) than in control subjects (98.44 ± 6.83 μm). BCR was correlated with OCT average RNFL thickness (r = -0.48, P = 0.002) in patients with MS without optic neuritis. Significant correlations were found between average RNFL thickness and EDSS (r = -0.43, P = 0.003). Additionally, there were correlations between BCR with GDx parameters in patients with MS without optic neuritis.
  
  
  CONCLUSIONS
  This study shows that RNFL thickness correlates with BCR and with MS subtypes. Additionally, our study indicates that OCT is better suited for MS assessment than GDx. We conclude that the damage of retinal axons appears related to brain damage in patients with MS.
authors.affiliation: Service of Ophthalmology (JMA-L, CC-T, FG), Complexo Hospitalario Universitario de Santiago de Compostela, La Coruña, Spain; Department of Statistics (CCL, CC-S), School of Medicine, University of Santiago de Compostela, Spain; Service of Neurology (MAG), and Radiology (SBG), Complexo Hospitalario Universitario de Santiago de Compostela, Spain; Department of Surgery and CIMUS (FG), University of Santiago de Compostela, Spain; and Insituto de Investigacion Sanitaria (FG), Santiago de Compostela, Spain.
authors.forename: Jose Manuel
authors.initials: JM
authors.lastname: Abalo-Lojo
authors.forename: Carmen Carollo
authors.initials: CC
authors.lastname: Limeres
authors.forename: Manuel Arias
authors.initials: MA
authors.lastname: Gómez
authors.forename: Sandra
authors.initials: S
authors.lastname: Baleato-González
authors.forename: Carmen
authors.initials: C
authors.lastname: Cadarso-Suárez
authors.forename: Carmen
authors.initials: C
authors.lastname: Capeáns-Tomé
authors.forename: Francisco
authors.initials: F
authors.lastname: Gonzalez
mesh_terms: D000328:Adult; D001284:Atrophy / Q000473:pathology; D001921:Brain / Q000473:pathology*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000150:complications* / Q000534:rehabilitation; D009412:Nerve Fibers / Q000473:pathology*; D009902:Optic Neuritis / Q000209:etiology / Q000473:pathology* / Q000534:rehabilitation; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012189:Retrospective Studies; D057109:Scanning Laser Polarimetry; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence