The influence of axial length on retinal nerve fibre layer thickness and optic-disc size measurements by spectral-domain OCT

Giacomo Savini, Piero Barboni, Vincenzo Parisi, Michele Carbonelli

Research output: Contribution to journalArticle


Background: To evaluate the influence of axial length on measurements of the retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) parameters in healthy subjects. Methods: Using Cirrus HD-OCT, RNFL thickness and ONH parameters (disc and rim area) were measured in 15 short (25.51 mm) eyes. Results: The mean axial length was 21.5±0.5 mm in short eyes, 24.1±0.8 mm in medium eyes and 26.6±1.0 mm in long eyes. The RNFL thickness decreased with longer axial lengths in the superior (r=-0.52, r 2=0.27, p=0.0003), inferior (r=-0.72, r 2=0.52, p2=0.37, p2=0.09, p=0.0485) quadrants, as well as in the 360° mean measurement (r=-0.69, r 2=0.48, p2=0.54, p2=0.17, p=0.0051) decreased with longer axial lengths. Correcting for axial length-induced ocular magnification by means of the Littmann formula resolved the relationship between axial length and both RNFL thickness and ONH area. Discussion: Axial length influences measurements of RNFL thickness and ONH parameters in healthy subjects. Caution is recommended when comparing the measured values of myopic and hyperopic eyes with the normative database of the instrument.

Original languageEnglish
Pages (from-to)57-61
Number of pages5
JournalBritish Journal of Ophthalmology
Issue number1
Publication statusPublished - Jan 2012


ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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