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Detection of retinal nerve fibre layer progression: comparison of the fast and extended modes of GDx guided progression analysis
  1. Sara M Kjaergaard,
  2. Luciana M Alencar,
  3. Bac Nguyen,
  4. Patrick Sassani,
  5. Felipe A Medeiros,
  6. Robert N Weinreb,
  7. Linda M Zangwill
  1. Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, California, USA
  1. Correspondence to Dr Linda Zangwill, 9500 Gilman Drive, La Jolla, CA 92093-0946, USA; zangwill{at}


Purpose To compare detection of retinal nerve fibre layer changes using GDx guided progression analysis (GPA) fast mode (which assumes fixed variability of a reference population) and extended mode (which measures individual variability), and to determine how they compare with photography and conventional visual field-based methods for identifying glaucoma progression.

Methods 172 eyes from 117 participants in the Diagnostic Innovations in Glaucoma Study (12 healthy, 108 glaucoma suspects and 52 glaucoma eyes) with ≥4 GDx VCC visits and ≥3 good quality GDx VCC scans at each visit were included.

Results Agreement between the GDx GPA fast mode and GDx GPA extended mode was limited. The GDx fast mode and extended mode detected 15 and 18 eyes, respectively, as ‘likely progression’, but only seven of them agreed. The conventional reference standard (stereophotograph-based optic disc and/or visual field progression) identified nine eyes as progressing, of which two eyes were also identified by the GDx fast mode and three eyes by the extended mode. In the GDx fast mode, we found that the progression detection varied depending on which two scans were included in the baseline and follow-up images.

Conclusion There was limited agreement between the GDx fast mode and the GDx extended mode for progression detection, and between different scans included in the GDx fast mode progression analysis. Longer follow-up is needed to determine the proportion of eyes classified as ‘likely progression’ by the GDx analysis that are early change and the proportion that are false positive results.

  • glaucoma
  • imaging
  • diagnostic tests/investigation
  • glaucoma
  • field of vision
  • imaging
  • Intraocular pressure
  • optic nerve
  • diagnostic tests/investigation
  • epidemiology

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  • Disclosure RN Weinreb is a consultant to Carl Zeiss Meditec, Inc. and receives research equipment from Carl Zeiss Meditec. FA Medeiros receives research support/materials and honoraria from Carl Zeiss Meditec, Inc. LM Zangwill receives research equipment from Carl Zeiss Meditec, Inc.

  • Funding This study was supported in part by NEI R01-EY08208 (FAM), NEI R01-11008 (LMZ), and the Danish Eye Research Foundation. Participant retention incentive grants were provided in the form of glaucoma medication at no cost (Alcon Laboratories Inc., Allergan, Pfizer Inc., SANTEN Inc.).

  • Competing interests RN Weinreb is a consultant to Optovue Inc, Alcon Laboratories, Allergan Inc, Glaxo, and Pfizer Inc, and receives research materials/support from Heidelberg Engineering, GmbH,Optovue, Inc., Topcon Medical Systems, Inc., and Novartis. FA Medeiros is a consultant for Alcon Laboratories, Inc., Allergan, Inc. and Pfizer, receives research support/materials from Alcon, and Pfizer, Inc, and received honoraria from Alcon Laboratories Inc, Allergan Inc, Pfizer Inc, and Reichert, Inc. LM Zangwill receives research equipment from Heidelberg Engineering, GmbH, Optovue, Inc., and Topcon Medical Systems, Inc.

  • Patient consent Written informed consent was obtained from each participant.

  • Ethics approval Ethics approval was obtained from the Institutional Review Board of the UCSD Human Research Protection Program.

  • Provenance and peer review Not commissioned; externally peer reviewed.