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Effect of Optic Disc Size and Disease Severity on the Diagnostic Capability of Glaucoma Imaging Technologies in an Indian Population

Garudadri, Chandra S. MD, FRCS*; Rao, Harsha L. MD, DNB*; Parikh, Rajul S. MS*,†; Jonnadula, Ganesh B. B Opt*; Selvaraj, Prabhakaran B Opt*; Nutheti, Rishita PhD*; Thomas, Ravi MD*,‡,§

doi: 10.1097/IJG.0b013e31821829f1
Original Studies

Purpose To evaluate the influence of optic disc size and disease severity on the diagnostic validity of optical coherence tomography (Stratus OCT), scanning laser polarimetry [GDx variable corneal compensator (VCC)], and confocal scanning laser ophthalmoscopy [Heidelberg retina tomograph II (HRT II)] in Indian eyes with glaucoma.

Methods Ninety-five normal and 125 glaucoma patients underwent imaging with Stratus OCT, GDx VCC, and HRT II. One eye of each person was randomly selected for analysis. Using disc area determined on HRT II, discs were classified as small (<2 mm2), moderate (2 to 3 mm2), and large (>3 mm2). The parameter with the best sensitivity for each device, at a fixed specificity, was compared for different disc sizes. Logistic marginal regression was used to study the effect of disc size and disease severity (mean deviation on standard automated perimetry) on the diagnostic performance of these imaging devices.

Results At a fixed specificity of 84.2%, the sensitivity of HRT II was significantly different for varying disc sizes (P=0.0004). The sensitivities for dissimilar disc sizes were not significantly different for the GDx VCC (P=0.928) or Stratus OCT (P=0.381). Logistic marginal regression also showed that sensitivity of HRT II increased with increasing disc size, whereas sensitivity of OCT and GDx were independent of the disc size. The sensitivity of all 3 technologies increased with increasing disease severity (decreasing mean deviation).

Conclusions Optic disc size affects the diagnostic capability of HRT II but not that of GDx VCC or Stratus OCT. The sensitivity of all 3 imaging technologies increased with increasing disease severity.

*L V Prasad Eye Institute, Banjara Hills, Hyderabad

Bombay City Eye Institute and Research Centre, Babulnath, Mumbai, India

Queensland Eye Institute, South Brisbane, Qld

§University of Queensland, Australia

Disclosure: Garudadri CS was supported by Allergan (C) and Merck (C), Parikh RS was supported by Merck (C), and Thomas R was supported by Allergan (C). Rao HL, Jonnadula GB, Selvaraj P, and Nutheti R were supported by none.

Reprints: Chandra S. Garudadri, MD, FRCS, L V Prasad Eye Institute, Banjara Hills, Hyderabad 500034, India (e-mail:

Received August 4, 2010

Accepted February 28, 2011

© 2012 Lippincott Williams & Wilkins, Inc.