Advanced imaging for glaucoma study: design, baseline characteristics, and inter-site comparison

Am J Ophthalmol. 2015 Feb;159(2):393-403.e2. doi: 10.1016/j.ajo.2014.11.010. Epub 2014 Nov 8.


Purpose: To report the baseline characteristics of the participants in the Advanced Imaging for Glaucoma Study. To compare the participating sites for variations among subjects and the performance of imaging instruments.

Design: Multicenter longitudinal observational cohort study.

Methods: A total of 788 participants (1329 eyes) were enrolled from 3 academic referral centers. There were 145 participants (289 eyes) in the normal group, 394 participants (663 eyes) in the glaucoma suspect/preperimetric glaucoma group, and 249 participants (377 eyes) in the perimetric glaucoma group. Participants underwent a full clinical examination, standard automated perimetry, and imaging with time-domain and Fourier-domain optical coherence tomography (OCT), scanning laser polarimetry, and confocal scanning laser ophthalmoscopy. The baseline average, population standard deviation, and repeatability of imaging-derived anatomic variables were reported for each technology and center.

Results: Compared to the normal participants, glaucoma suspect/preperimetric glaucoma and perimetric glaucoma groups had significantly reduced anatomic measurements. Repeatability of nerve fiber layer thickness was best for Fourier-domain OCT (overall coefficient of variation <2%), followed by time-domain OCT (coefficient of variation 2%-2.9%), scanning laser polarimetry (coefficient of variation 2.6%-4.5%), and confocal scanning laser ophthalmoscopy rim area (coefficient of variation 4.2%-7.6%). A mixed-effects model showed that the differences between sites was less than 25 percent of the variation within groups and less than the differences between the normal and glaucoma suspect/preperimetric glaucoma group.

Conclusions: Site-to-site variation was smaller than both the variation within groups and the changes attributable to glaucoma. Therefore pooling of participants between sites is appropriate.

Publication types

  • Comparative Study
  • Multicenter Study
  • Observational Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Diagnostic Imaging / methods*
  • Female
  • Follow-Up Studies
  • Fourier Analysis
  • Glaucoma / diagnosis*
  • Humans
  • Intraocular Pressure
  • Male
  • Middle Aged
  • Nerve Fibers / pathology*
  • Ocular Hypertension / diagnosis
  • Ophthalmoscopy
  • Optic Disk / pathology*
  • Optic Nerve Diseases / diagnosis*
  • Predictive Value of Tests
  • Prospective Studies
  • Reproducibility of Results
  • Research Design
  • Retinal Ganglion Cells / pathology*
  • Scanning Laser Polarimetry
  • Tomography, Optical Coherence
  • Visual Field Tests