June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Variability of Retinal Thickness Measurements in Tilted or Stretched Optical Coherence Tomography Images
Author Affiliations & Notes
  • Akihito Uji
    Doheny Eye Institute, Los Angeles, California, United States
    Ophthalmology, David Geffen School of Medicine at the University of California-Los Angeles, Los Angeles, California, United States
  • Nizar Saleh Abdelfattah
    Doheny Eye Institute, Los Angeles, California, United States
    Ophthalmology, David Geffen School of Medicine at the University of California-Los Angeles, Los Angeles, California, United States
  • David S Boyer
    Retina Vitreous Associates Medical Group, Beverly Hills, California, United States
  • Siva Balasubramanian
    Doheny Eye Institute, Los Angeles, California, United States
    Ophthalmology, David Geffen School of Medicine at the University of California-Los Angeles, Los Angeles, California, United States
  • Jianqin Lei
    Doheny Eye Institute, Los Angeles, California, United States
    Ophthalmology, David Geffen School of Medicine at the University of California-Los Angeles, Los Angeles, California, United States
  • Srinivas R Sadda
    Doheny Eye Institute, Los Angeles, California, United States
    Ophthalmology, David Geffen School of Medicine at the University of California-Los Angeles, Los Angeles, California, United States
  • Footnotes
    Commercial Relationships   Akihito Uji, None; Nizar Abdelfattah, None; David Boyer, Aerpio (C), Alcon (C), Alcon (R), Bayer (C), Genentech (C), Genentech (R), GS (C), KalVista (C), Neurotech (C), Nicox (C), Novartis (C), Novartis (R), Ohr (C), RRegeneron Pharmaceuticals, Inc. (C), RRegeneron Pharmaceuticals, Inc. (R), Santaris (C), Santen (C), ThromboGenics (C); Siva Balasubramanian, None; Jianqin Lei, None; Srinivas Sadda, Allergan (F), Allergan (C), Carl Zeiss Meditec (F), Centervue (C), Genentech (F), Genentech (C), Iconic (C), Novartis (C), Optos (F), Optos (C), Thrombogenics (C)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 1323. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to Subscribers Only
      Sign In or Create an Account ×
    • Get Citation

      Akihito Uji, Nizar Saleh Abdelfattah, David S Boyer, Siva Balasubramanian, Jianqin Lei, Srinivas R Sadda; Variability of Retinal Thickness Measurements in Tilted or Stretched Optical Coherence Tomography Images. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1323.

      Download citation file:


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

      ×
  • Supplements
Abstract

Purpose : Despite having a higher axial than tranverse resolution, optical coherence tomography (OCT) images are typically displayed in an axially-stretched manner. As a result, thickness measurements perpendicular to the plane of the retina will be over-estimated unless this stretching is taken into account. The purpose of this study is to investigate the magnitude of inaccuracy in retinal thickness measurements from tilted and axially-stretched OCT images.

Methods : A consecutive series of 50 eyes of 50 patients with age-related macular degeneration were included in this retrospective IRB-approved study. OCT B-scans (Cirrus HD-OCT) through the foveal center were used for this analysis, and the rotation angle of the B-scan was computed. The foveal thickness was measured in three ways: (a) parallel to the orientation of the A-scan (Tx), (b) perpendicular to the retinal pigment epithelium (RPE) surface in the instrument-displayed aspect ratio image (Ty), and thickness measured perpendicular to the RPE surface in a native (“true”) aspect ratio image (Tz). Mathematical modeling was also performed to estimate the measurement error at various angles of tilting and axial stretching.

Results : The average rotation angle was 12.8 ± 6.3 degrees. FTx (224 ± 52µm) and FTy (235 ± 54µm) were significantly larger than FTz (222 ± 51µm) (both P < 0.0001), and FTy was significantly larger than FTx (P < 0.0001). Moreover, the FTy/FTz ratio was 1.06 ± 0.05, and was larger than the FTx/FTz ratio of 1.01 ± 0.01 (P < 0.0001). Both FTx/FTz and FTy/FTz ratios increased as the angle increased, however, the increase in FTx/FTz was more gradual than for FTy/FTz. FTy/FTz ranged from 1.00 to 1.21. In the simulation, with axial stretching by a factor of 2, Ty/Tz ratio was > 1.05 at a tilt angle between 13 to 77 degrees, > 1.10 at a tilt angle between 19 to 71 degrees, and >1.20 at an angle ranging from 32 to 58 degrees. Of note, with more axial stretching, the Ty/Tz ratio rises further. Tx/Tz ratio was smaller than the Ty/Tz ratio at angles ranging from 0 to 54 degrees. The actual patient data showed good agreement with the simulation.

Conclusions : Retinal thickness measurements obtained perpendicular to the RPE surface were overestimated when using tilted and axially-stretched OCT images. If accurate measurements are to be obtained, images with a native aspect ratio similar to microscopy should be used.

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

×
×

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.

×