Article Text

Download PDFPDF
SD-OCT peripapillary nerve fibre layer and ganglion cell complex parameters in glaucoma: principal component analysis
  1. Marta Pazos1,2,
  2. Marc Biarnés2,
  3. Andrés Blasco-Alberto3,
  4. Agnieszka Dyrda4,
  5. Miguel Ángel Luque-Fernández5,6,
  6. Alicia Gómez4,
  7. Clara Mora7,
  8. Elena Milla1,
  9. MªJesús Muniesa1,
  10. Alfonso Antón4,7,8,
  11. Valentín Tinguaro Díaz-Alemán3
  1. 1 Institut Clínic d'Oftalmologia, Hospital Clínic de Barcelona. Universitat de Barcelona, Barcelona, Spain
  2. 2 Institut de la Màcula, Barcelona Macula Foundation (Hospital Quirón-Teknon), Barcelona, Spain
  3. 3 Ophthalmology, Hospital Universitario de Canarias, Universidad de la Laguna, Tenerife, Spain
  4. 4 Glaucoma and Research, Institut Català de Retina, Barcelona, Spain
  5. 5 Non-communicable Disease and Cancer Epidemiology Group, Biomedical Research Institute of Granada (ibs.GRANADA), Granada, Spain
  6. 6 Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
  7. 7 Ophthalmology, Hospital de l'Esperança-Parc de Salut Mar, Barcelona, Spain
  8. 8 Ophthalmology, Universitat Internacional de Catalunya Facultat de Medicina i Ciències de la Salut, Sant Cugat del Valles, Spain
  1. Correspondence to Dr Marta Pazos, Ophthalmology, Institut Clínic d’Oftalmologia, Hospital Clínic Barcelona, Universitat de Barcelona, Barcelona 08028, Spain; martapazoslopez{at}


Background/aims To identify objective glaucoma-related structural features based on peripapillary (p) and macular (m) spectral domain optical coherence tomography (SD-OCT) parameters and assess their discriminative ability between healthy and glaucoma patients.

Methods Two hundred and sixty eyes (91 controls and 169 glaucoma) were included in this prospective study. After a complete examination, all participants underwent the posterior pole and the peripapillary retinal nerve fibre layer (pRNFL) protocols of the Spectralis SD-OCT. Principal component analysis (PCA), a data reduction method, was applied to identify and characterise the main information provided by the ganglion cell complex (GCC). The discriminative ability between healthy and glaucomatous eyes of the first principal components (PCs) was compared with that of conventional SD-OCT parameters (pRNFL, macular RNFL (mRNFL), macular ganglion cell layer (mGCL)and macular inner plexiform layer (mIPL)) using 10-fold cross-validated areas under the curve (AUC).

Results The first PC explained 58% of the total information contained in the GCC and the pRNFL parameters and was the result of a general combination of almost all variables studied (diffuse distribution). Other PCs were driven mainly by pRNFL and mRNFL measurements. PCs and pRNFL had similar AUC (0.95 vs 0.96, p=0.88), and outperformed the other structural measurements: mRNFL (0.91, p=0.002), mGCL (0.92, p=0.02) and mIPL (0.92, p=0.0001).

Conclusions PCA identified a diffuse representation of the papillary and macular SD-OCT parameters as the most important PC to summarise structural data in healthy and glaucomatous eyes. PCs and pRNFL parameters showed the greatest discriminative ability between healthy and glaucoma cases.

  • glaucoma
  • imaging
  • diagnostic tests/investigation
  • optic nerve

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Twitter @MartaPazosMD

  • Contributors Here follow the contributions of each author: Conception and design: MP, MB, VTDA. Analysis and interpretation: MP, MB, VTDA and MAL-F. Data collection: MP, AB-A, AD, MAL-F, EM, MM, AA and CM. Manuscript preparation: MP, VTDA and AD. Overall responsibility: MP, MB and VTDA.

  • 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.

  • Patient consent for publication Not required.

  • Ethics approval This study was approved by the Ethical Committee and was conducted in accordance with the tenets of the Declaration of Helsinki.

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

  • Data availability statement Data are available on reasonable request. Data may be obtained from a third party and are not publicly available. All data relevant to the study are included in the article or uploaded as online supplementary information. Please, contact the corresponding author (

Linked Articles

  • At a glance
    Frank Larkin