title: Optic Nerve Head and Retinal Nerve Fiber Layer Differences Between Caribbean Black and African American Patients as Measured by Spectral Domain OCT.
abstract: OBJECTIVE
  There are well-established differences in optic nerve morphology between patients of African and European descent. Spectral domain optical coherence tomography (OCT) scanning has demonstrated these differences with respect to optic disc area (DA), average cup-disc ratio, cup volume, and nerve fiber layer thickness. However, the term "African descent" describes a heterogenous group with considerable variability. This study evaluates differences in optic nerve and retinal nerve fiber layer (RNFL) parameters as measured by Cirrus HD-OCT between Caribbean black and African American patients.
  
  
  METHODS
  A total of 25 African American subjects and 25 Caribbean black subjects with normal ocular examinations were consecutively recruited to this study. All patients received imaging of the optic nerve and nerve fiber layer with Cirrus HD-OCT. Optic nerve and RNFL parameters were evaluated for statistically significant differences using a t test. A mixed effect model for correlated data was then created to adjust outcome variables for (1) repeated measures and (2) optic nerve size. Two one-sided t tests were then utilized to determine equivalence.
  
  
  RESULTS
  After adjustment for DA, RNFL thickness, cup volume, DA, inferior nerve fiber layer, and vertical cup-disc ratio demonstrated statistically significant equivalence between the 2 groups (P value <0.05). The superior nerve fiber layer quadrant was significantly different between the 2 groups and may merit further investigation.
  
  
  CONCLUSIONS
  Findings of this study suggest that optic nerve and RNFL morphology is markedly similar between Caribbean blacks and African Americans once adjusted for optic nerve size but cannot be considered equivalent in all measures, particularly in the superior nerve fiber layer.
authors.affiliation: *Department of Ophthalmology, Harkness Eye Institute †Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY.
authors.forename: Rohini
authors.initials: R
authors.lastname: Rao
authors.forename: Elona
authors.initials: E
authors.lastname: Dhrami-Gavazi
authors.forename: Lama
authors.initials: L
authors.lastname: Al-Aswad
authors.forename: Adam
authors.initials: A
authors.lastname: Ciarleglio
authors.forename: George A
authors.initials: GA
authors.lastname: Cioffi
authors.forename: Dana M
authors.initials: DM
authors.lastname: Blumberg
mesh_terms: D001741:Black or African American / Q000208:ethnology*; D044383:Black People / Q000208:ethnology*; D017691:Caribbean Region / Q000208:ethnology; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers; D009898:Optic Disk / Q000033:anatomy & histology*; D012165:Retinal Ganglion Cells / Q000166:cytology*; D041623:Tomography, Optical Coherence / Q000379:methods