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Analysis of deep optic nerve head structures with spectral domain and swept-source optical coherence tomography
  1. Rami Darwich1,
  2. Faisal Jarrar2,
  3. Mustafa Syed2,
  4. Glen P Sharpe1,
  5. Balwantray C Chauhan1
  1. 1 Department of Ophthalmology and Visual Sciences, Dalhousie University and Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
  2. 2 Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
  1. Correspondence to Dr Balwantray C Chauhan, Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax B3H 2Y9, Canada; bal{at}


Purpose Histological evidence indicates that the earliest structural changes to the optic nerve head (ONH) in glaucoma occur in the lamina cribrosa (LC) and its interface with the sclera. However, clinical imaging of these structures remains challenging. We compared the visibility of deep ONH structures with newer iterations of spectral-domain (SD) and swept-source (SS) optical coherence tomography (OCT).

Methods Twelve patients with open-angle glaucoma were imaged with SD-OCT with 24 radial B-scans centred on Bruch’s membrane opening (BMO) and SS-OCT with a horizontal and vertical raster scan pattern containing five lines each, centred on the ONH. Single best-matched horizontal and vertical scans from the two modalities were selected and exported. Three independent observers masked to modality determined if BMO, posterior choroid surface, anterior scleral canal opening and anterior and posterior LC insertions into the sclera were detectable in the matched B-scan images. We determined the interobserver agreement and concordance in detecting each structure with the two OCT imaging modalities.

Results There was a high interobserver agreement with both SS-OCT and SD-OCT (inter-item correlations: 0.81–0.93 and 0.77–0.82, respectively). There was a consistent tendency for higher overall detection rates with SS-OCT, however, the differences failed to reach statistical significance. With respect to individual structures, only the posterior LC insertion in the nasal quadrant was statistically different, with a detection rate of 13 and 6 (pooled out of a total of 36 across the three observers) with SS-OCT and SD-OCT, respectively (p=0.04).

Conclusion Overall, both SS-OCT and SD-OCT showed statistically equivalent visualisation of ONH structures, however, SS-OCT tended to have higher visualisation rates.

  • optic nerve
  • imaging
  • glaucoma

Data availability statement

Data are available upon reasonable request. No data are available.

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Data availability statement

Data are available upon reasonable request. No data are available.

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  • Contributors RD and BCC are responsible for the overall content and serve as guarantor of this work.

    RD, GPS and BCC conceived and planned the study. FJ and MS performed manual image segmentation. RD analysed the data and performed statistical analysis. RD and BCC wrote the paper with input from all authors. BCC supervised the project.

  • Funding Canadian Institutes of Health Research, Ottawa, Canada (grant no.: MOP11357 (B.C.C.)); Topcon Medical Systems, Oakland (equipment support); Heidelberg Engineering, Heidelberg, Germany (equipment support).

  • Competing interests None declared.

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

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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