title: Variation of the axial location of Bruch's membrane opening with age, choroidal thickness, and race.
abstract: OBJECTIVE
  This study explores variation in the axial location of Bruch's membrane opening (BMO) to determine if this reference plane varies with age and race.
  
  
  METHODS
  There were 168 spectral-domain optical coherence tomography (SDOCT) optic nerve head volumes that were obtained from healthy subjects and manually delineated within 24 axial slices to develop point clouds for Bruch's membrane and anterior scleral surfaces. A BMO-independent reference plane was generated based on the peripapillary sclera to measure BMO position. General estimating equations were used to determine the relationship of the axial position of BMO (BMO height) with choroidal thickness, age, and race (African Descent [AD] versus European Descent [ED]) controlling for variations in axial length.
  
  
  RESULTS
  The peripapillary choroid was thinner with increasing axial length (-14.9 μm/mm, P = 0.0096), advancing age (-1.1 μm/y, P = 0.00091), and in the ED group (20.2 μm, P = 0.019) in a multivariable model. Choroidal thickness was also strongly related to BMO height (P < 0.00001) independent of all covariates. Bruch's membrane opening position was more posterior relative to the sclera in older subjects (1.3 μm/y, P = 0.00017), independent of axial length and race. However, when choroidal thickness was included in the model, this association was lost (P = 0.225). There was no significant difference in BMO height between racial groups after adjustment for age and axial length.
  
  
  CONCLUSIONS
  Bruch's membrane opening is more posteriorly located in older individuals. These differences are largely due to differences in choroidal thickness and suggest that BMO migrates posteriorly with age due to age-related choroidal thinning. However, additional studies in longitudinal datasets are needed to validate these findings.
authors.affiliation: Department of Computer and Information Sciences, College of Arts and Sciences, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: John
authors.initials: J
authors.lastname: Johnstone
authors.forename: Massimo
authors.initials: M
authors.lastname: Fazio
authors.forename: Kulawan
authors.initials: K
authors.lastname: Rojananuangnit
authors.forename: Brandon
authors.initials: B
authors.lastname: Smith
authors.forename: Mark
authors.initials: M
authors.lastname: Clark
authors.forename: Crawford
authors.initials: C
authors.lastname: Downs
authors.forename: Cynthia
authors.initials: C
authors.lastname: Owsley
authors.forename: Michael J A
authors.initials: MJ
authors.lastname: Girard
authors.forename: Jean Martial
authors.initials: JM
authors.lastname: Mari
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Girkin
mesh_terms: D058452:Axial Length, Eye; D016570:Bruch Membrane / Q000473:pathology*; D002829:Choroid / Q000473:pathology*; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000208:ethnology / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D015995:Prevalence; D044469:Racial Groups; D012590:Sclera / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*; D014481:United States
keywords: choriocapillaris; optic nerve head; optical coherence tomography