Repeatability of in vivo corneal confocal microscopy to quantify corneal nerve morphology

Ioannis N. Petropoulos, Tauseef Manzoor, Philip Morgan, Hassan Fadavi, Omar Asghar, Uazman Alam, Georgios Ponirakis, Mohammad A. Dabbah, Xin Chen, James Graham, Mitra Tavakoli, Rayaz A. Malik

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Purpose: To establish intraobserver and interobserver repeatability, agreement, and symmetry of corneal nerve fiber (NF) morphology in healthy subjects using in vivo corneal confocal microscopy. Methods: Nineteen subjects underwent in vivo corneal confocal microscopy (Heidelberg Retinal Tomograph III Rostock Cornea Module) at baseline and 7 days apart. Bland-Altman plots were generated to assess agreement, and the intraclass correlation coefficient and coefficient of repeatability were calculated to estimate intraobserver and interobserver repeatability for corneal NF density (numbers per square millimeter), nerve branch density (NBD; numbers per square millimeter), NF length (millimeters per square millimeter), and NF tortuosity coefficient. Symmetry between the right and left eyes was also assessed. Results: Intraclass correlation coefficient and coefficient of repeatability for intraobserver repeatability were 0.66 to 0.74 and 0.17 to 0.64, for interobserver repeatability 0.54 to 0.93 and 0.15 to 0.85, and for symmetry 0.34 to 0.77 and 0.17 to 0.63, respectively. NBD demonstrated low repeatability. Conclusions: This study demonstrates good repeatability for the manual assessment of all major corneal NF parameters with the exception of NBD, which highlights the difficulty in defining nerve branches and suggests the need for experienced observers or automated image analysis to ensure optimal repeatability.

Original languageEnglish
Pages (from-to)e83-e89
Issue number5
Publication statusPublished - 1 May 2013



  • In vivo corneal confocal microscopy
  • diabetic neuropathy
  • repeatability

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Petropoulos, I. N., Manzoor, T., Morgan, P., Fadavi, H., Asghar, O., Alam, U., Ponirakis, G., Dabbah, M. A., Chen, X., Graham, J., Tavakoli, M., & Malik, R. A. (2013). Repeatability of in vivo corneal confocal microscopy to quantify corneal nerve morphology. Cornea, 32(5), e83-e89.