title: Retinal ganglion cell layer volumetric assessment by spectral-domain optical coherence tomography in multiple sclerosis: application of a high-precision manual estimation technique.
abstract: BACKGROUND
  Neuronal loss in the retina has been demonstrated pathologically in eyes of patients with multiple sclerosis (MS). In vivo, MS eyes have reduced total macular volumes by optical coherence tomography (OCT). Using a high-resolution spectral-domain OCT, this pilot study used a manual method to measure ganglion cell layer (GCL) volumes and to determine the relation of these volumes to visual function in MS eyes.
  
  
  METHODS
  Sixteen eyes of 8 patients with MS and 8 eyes of 5 disease-free control participants were studied using fast macular OCT scans performed with Spectralis OCT (Heidelberg Engineering). Visual function tests of low-contrast letter acuity and high-contrast visual acuity were administered.
  
  
  RESULTS
  MS patient eyes had significantly lower GCL volumes than the control eyes (P < 0.001 vs controls, generalized estimating equation regression models accounting for age and within-patient intereye correlations). Within the MS group, eyes with a history of optic neuritis (ON, n = 4) had significantly lower GCL volumes than MS eyes with no ON history (P < 0.001). In contrast to measures of high-contrast visual acuity (P = 0.14), decreased GCL volumes were associated with worse performance on low-contrast letter acuity testing (P = 0.003).
  
  
  CONCLUSIONS
  This pilot study has characterized thinning of the GCL in MS patient eyes, particularly in those with a history of acute ON, which corresponded to a reduced performance on low-contrast letter acuity testing. Studies utilizing computerized segmentation algorithms will continue to facilitate the detection of GCL loss on a larger scale and provide important information in vivo on the role and timing of neuronal vs axonal loss in MS eyes.
authors.affiliation: Departments of Neurology University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Emma C
authors.initials: EC
authors.lastname: Davies
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Galetta
authors.forename: David J
authors.initials: DJ
authors.lastname: Sackel
authors.forename: Lauren S
authors.initials: LS
authors.lastname: Talman
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Frohman
authors.forename: Peter A
authors.initials: PA
authors.lastname: Calabresi
authors.forename: Steven L
authors.initials: SL
authors.lastname: Galetta
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Balcer
mesh_terms: D000328:Adult; D003941:Diagnostic Techniques, Ophthalmological / Q000592:standards*; D006801:Humans; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D010865:Pilot Projects; D011446:Prospective Studies; D012162:Retinal Degeneration / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods* / Q000592:standards*