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Impact of segmentation density on spectral domain optical coherence tomography assessment in Stargardt disease

  • Swetha Bindu Velaga
  • Muneeswar Gupta Nittala
  • Dennis Jenkins
  • J. Melendez
  • Alexander Ho
  • R. W. Strauss
  • H. P. Scholl
  • SriniVas R. SaddaEmail author
Retinal Disorders
  • 21 Downloads

Abstract

Purpose

Automated spectral domain optical coherence tomography (SD-OCT) segmentation algorithms currently do not perform well in segmenting individual intraretinal layers in eyes with Stargardt disease (STGD). We compared selective B-scan segmentation strategies for generating mean retinal layer thickness and preserved area data from SD-OCT scans in patients with STGD1.

Methods

Forty-five eyes from 40 Stargardt patients were randomly selected from the ongoing Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) study. All eyes underwent SD-OCT using a standard macular volume consisting of 1024 × 49 equally spaced B-scans within a 20 × 20 degree field centered on the fovea. All 49 B-scans were segmented manually to quantify total retina, outer nuclear layer (ONL), photoreceptor inner segments, photoreceptor outer segments (OS), and retinal pigment epithelial layer (RPE). Mean thickness and total area were generated using all 49 B-scans (spaced 122 μm apart), 25 B-scans (every other B-scan, spaced 240 μm apart), 17 B-scans (every third scan, 353 μm apart), and 13 B-scans (every fourth scan, 462 μm apart), as well as by using an “adaptive” method where a subset (minimum 25 B-scans) of B-scans that the grader deemed as significantly different from adjacent B-scans were utilized. Mean absolute and percentage errors were calculated for macular thickness and area of different retinal layers for the different B-scan subset selection strategies relative to using all 49 B-scans, which was considered the reference or ground truth.

Results

Mean thickness and area measurements were significantly different for any regularly spaced reduction in B-scan density relative to the ground truth. When an adaptive approach was applied using a minimum of half the scans, the differences relative to ground truth were no longer significantly different. The mean percent differences for the area and thicknesses of the various layers ranged from 0.02 to 33.66 (p < 0.05 for all comparisons) and 0.44 to 7.24 (p > 0.05) respectively.

Conclusion

Manual segmentation of a subset of B-scans using an adaptive strategy can yield thickness and area measurements of retinal sublayers comparable to the reference ground truth derived from using all B-scans in the volume. These results may have implications for increasing the efficiency of SD-OCT grading strategies in clinical trials for STGD and other related macular degenerative disorders.

Keywords

Stargardt Segmentation density Spectral domain optical coherence tomography Retinal layers 

Notes

Compliance with ethical standards

Data collection and analyses were approved by the Institutional Review Board of the University of California Los Angeles

Conflict of interest

Dr. Sadda receives research support from Carl Zeiss Meditec, Optos, and serves as a consultant to Optos, Heidelberg, and Centervue. Other authors have no financial disclosures.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.

References

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Swetha Bindu Velaga
    • 1
  • Muneeswar Gupta Nittala
    • 1
  • Dennis Jenkins
    • 1
  • J. Melendez
    • 1
  • Alexander Ho
    • 1
  • R. W. Strauss
    • 2
    • 3
    • 4
    • 5
  • H. P. Scholl
    • 2
  • SriniVas R. Sadda
    • 1
    • 6
    Email author
  1. 1.Doheny Eye InstituteLos AngelesUSA
  2. 2.Wilmer Eye InstituteJohns Hopkins UniversityBaltimoreUSA
  3. 3.Moorfield’s Eye Hospital NHS Foundation Trust and UCL Institute of OphthalmologyUniversity College LondonLondonUK
  4. 4.Department of OphthalmologyMedical University GrazGrazAustria
  5. 5.Department of OphthalmologyJohannes Kepler University LinzLinzAustria
  6. 6.Department of OphthalmologyDavid Geffen School of Medicine at UCLALos AngelesUSA

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