Article Text

Variability of vertical cup to disc ratio measurement and the effects of glaucoma 5-year risk estimation in untreated ocular hypertensive eyes
  1. Poemen Pui Man Chan1,2,
  2. Vivian S M Chiu1,
  3. Mandy O I Wong1,2
  1. 1Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Hong Kong, China
  2. 2Hong Kong Eye Hospital, Hong Kong, China
  1. Correspondence to Dr Poemen Pui Man Chan, Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Hong Kong, China; poemen{at}


Aim To compare the vertical cup to disc ratio (VCDR) measurements obtained with optical coherence tomography (OCT), Heidelberg retina tomography (HRT) and stereophotography of the optic nerve head (ONH) in patients with ocular hypertension (OHT), and their corresponding estimated 5-year risk for development of glaucoma.

Methods ONH images of patients with OHT were taken by fundus camera (stereoscopic images), OCT and HRT. Optic disc stereophotographs were evaluated with a stereo-viewer by two glaucoma specialists (SP1 and SP2) and the VCDR was measured with the ImageJ software. VCDR measurements obtained with stereophotography, OCT and HRT were used to calculate the estimated 5-year risk.

Results One hundred and forty eyes of 75 patients with OHT were included. The VCDR values measured by OCT, HRT, SP1 and SP2 were 0.60±0.14, 0.53±0.23, 0.44±0.13 and 0.49±0.10, respectively. The corresponding 5-year risk for development of glaucoma was 19.54%±16.60%, 18.13%±16.96%, 15.64%±14.35% and 16.70%±14.49%, respectively. Different degrees of proportional biases were observed in VCDR measurements obtained with stereophotography, OCT and HRT. The maximum difference of VCDR measurement was 0.64, while the maximum difference of the corresponding 5-year risk was 24.02%.

Conclusion The disagreement in VCDR measured by OCT, HRT and stereophotography in untreated OHT eyes extends to their 5-year risk estimation of glaucoma development.

  • ocular hypertension (OH)
  • vertical cup-disc ratio (VCDR)
  • cirrus high- density cirrus ocular coherence tomography (OCT)
  • Heidelberg retina tomograph (HRT)
  • stereophotograph
  • glaucoma 5-year risk estimator

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  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Ethics approval The protocol was approved in full by the Institutional Review Board of The Chinese University of Hong Kong.

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

  • Patient consent Obtained.

  • Contributors PPMC, VSMC and MOIW contributed to implementation, measurement of VCDR, data collection and approval of the final manuscript. VSMC also contributed to data analysis. In addition, PPMC contributed to study design, statistical calculation and writing up the manuscript.

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