title: Longitudinal and Cross-Sectional Analyses of Age Effects on Retinal Nerve Fiber Layer and Ganglion Cell Complex Thickness by Fourier-Domain OCT.
abstract: OBJECTIVE
  We studied the effects of age and intraocular pressure (IOP) on retinal nerve fiber layer (NFL) and macular ganglion cell complex (GCC) thickness in normal eyes.
  
  
  METHODS
  Data from subjects from the multicenter Advanced Imaging for Glaucoma Study (AIGS) were analyzed. The data included yearly visits from the normal subjects in the AIGS study. Fourier-domain optical coherence tomography (FD-OCT) was used to measure retinal NFL and macular GCC on each visit. Mixed effect models were used to evaluate the longitudinal effect of age and IOP on the NFL and GCC thickness. The measurements at baseline were used to examine the cross-sectional effects.
  
  
  RESULTS
  The analysis included 192 eyes (92 participants) from AIGS between 2009 and 2013. The longitudinal analyses showed overall GCC thickness decreased 0.25 ± 0.05 μm per year (P< 0.001) while the overall NFL thickness decreased 0.14 ± 0.07 μm per year (P= 0.04). The cross-sectional analyses showed the GCC thickness was 0.17 ± 0.05 μm thinner per year of baseline age (P< 0.001), while the NFL was 0.21 ± 0.06 μm thinner (P< 0.001). There was no significant IOP effect on either GCC or NFL from either the longitudinal or cross-sectional analysis.
  
  
  CONCLUSIONS
  Longitudinal and cross-sectional analyses provided consistent rates of approximately 0.2% per year of age-related thinning in NFL and GCC thicknesses. This is relevant in establishing criteria to detect glaucoma-related thinning (disease progression) in excess of normal aging. IOP does not seem to be a significant confounder for progression analysis.
  
  
  CONCLUSIONS
  This study demonstrated the relevance of advanced imaging technology in diagnosing and monitoring glaucoma disease.
authors.affiliation: Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Xinbo
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Doheny Eye Institute, University of California-Los Angeles, Los Angeles, CA, USA.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Francis
authors.affiliation: Doheny Eye Institute, University of California-Los Angeles, Los Angeles, CA, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Dastiridou
authors.affiliation: Doheny Eye Institute, University of California-Los Angeles, Los Angeles, CA, USA.
authors.forename: Vikas
authors.initials: V
authors.lastname: Chopra
authors.affiliation: Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Ou
authors.initials: O
authors.lastname: Tan
authors.affiliation: USC Eye Institute, University of Southern California, Los Angeles, CA, USA.
authors.forename: Rohit
authors.initials: R
authors.lastname: Varma
authors.affiliation: Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Greenfield
authors.affiliation: UPMC Eye Center, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Joel S
authors.initials: JS
authors.lastname: Schuman
authors.affiliation: Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA.
authors.forename: David
authors.initials: D
authors.lastname: Huang
keywords: ganglion cell complex; nerve fiber layer; optic nerve head; optical coherence tomography (OCT); thinning