June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Axial scaling of OCT retinal images is independent of axial length
Author Affiliations & Notes
  • Alexander E Salmon
    Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Benjamin S Sajdak
    Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Ross F Collery
    Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
    Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Joseph Carroll
    Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
    Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Footnotes
    Commercial Relationships   Alexander Salmon, None; Benjamin Sajdak, None; Ross Collery, None; Joseph Carroll, None
  • Footnotes
    Support  T32EY014537, R01EY017607, P30EY001931
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 4430. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to Subscribers Only
      Sign In or Create an Account ×
    • Get Citation

      Alexander E Salmon, Benjamin S Sajdak, Ross F Collery, Joseph Carroll; Axial scaling of OCT retinal images is independent of axial length. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4430.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Purpose : Literature reports1 of an effect of axial length (AL) on axial scaling in OCT conflict with standard models of axial scaling that are independent of optical power. We sought to investigate the effect of AL on axial scaling and identify the source of the reported effect.

Methods : A model eye was constructed comprising a 19mm lens and a translatable mount housing a glass coverslip at the retinal plane. The AL of the model eye was adjusted (~14-28mm) and the coverslip thickness was measured using the software calipers on a Heidelberg Spectralis OCT/SLO and a Bioptigen Envisu OCT. For the Spectralis, optical power-related eye data (AL, corneal curvature (CC), and refraction) were varied before acquisition of OCT scans to examine possible software sources of axial scaling error. The experiments were repeated with a Spectralis for 3 human subjects with short (AL ≤ 22.5mm), medium (22.5mm < AL ≤ 25.5mm), or long (AL > 25.5mm) eyes, and foveal thickness was measured. Using the Envisu, coverslip thickness was measured as a function of reference arm path length.

Results : Using the model eye, no effect was found between AL and coverslip thickness on the Envisu (Pearson’s correlation: p=0.30, R2=0.79, n=3) or Spectralis (p=0.32, R2=0.77, n=3; Fig. 1). Thickness measurements were unaffected by varying eye data in the Spectralis software (CC: p=0.56, R2=0.13, n=5; refraction: 1µm difference over a range of 14 diopters). The range of all measurements for 3 model eye ALs, each under 4 AL settings, was 3µm compared to the reported 22µm for a similar range of ALs.1 Thickness measurements were unaffected by varying Envisu reference arm path length (p=0.83, R2=0.0096, n=7). ALs of the human subjects were 22.26mm (short), 24.07mm (medium), and 26.92mm (long), and foveal thickness measurements were unaffected by varying eye data (AL: n-way ANOVA, p=0.27, n=3; CC: 2-way ANOVA, p=0.23, n=2; refraction: 2-way ANOVA, p=1.00, n=2).

Conclusions : Axial scaling in OCT appears to be independent of AL. No explanation of the previously reported effect was found, but software errors were ruled out. Conclusions drawn from reports in which axial scaling was adjusted based on AL should be reevaluated.
1Röck PMID:25298411

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Figure 1. Discrepancy between observed model eye AL/axial scale relationship and previously reported model.

Figure 1. Discrepancy between observed model eye AL/axial scale relationship and previously reported model.

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×