July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Quantification of RPE changes in choroideremia using a Photoshop-based protocol
Author Affiliations & Notes
  • Yi Zhai
    Department of Ophthalmology and Visual Sciences, University of Alberta, Edmonton, Alberta, Canada
  • Manlong Xu
    Department of Ophthalmology and Visual Sciences, University of Alberta, Edmonton, Alberta, Canada
  • Ioannis Dimopoulos
    Department of Ophthalmology, University of Ottawa, Ottawa, Ontario, Canada
  • David G Birch
    Retina Foundation of the Southwest, Dallas, Texas, United States
  • Paul S Bernstein
    Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
  • Peter Francis
    4D Molecular, California, United States
  • Jenny Holt
    4D Molecular, California, United States
  • David Kirn
    4D Molecular, California, United States
  • Ian M MacDonald
    Department of Ophthalmology and Visual Sciences, University of Alberta, Edmonton, Alberta, Canada
  • Footnotes
    Commercial Relationships   Yi Zhai, None; Manlong Xu, None; Ioannis Dimopoulos, None; David Birch, None; Paul Bernstein, None; Peter Francis, 4D molecular (E); Jenny Holt, 4D molecular (E); David Kirn, 4D molecular (E); Ian MacDonald, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 6131. doi:
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    • Get Citation

      Yi Zhai, Manlong Xu, Ioannis Dimopoulos, David G Birch, Paul S Bernstein, Peter Francis, Jenny Holt, David Kirn, Ian M MacDonald; Quantification of RPE changes in choroideremia using a Photoshop-based protocol. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6131.

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

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Purpose : To confirm fundus autofluorescence (FAF) area as a marker for disease progression in subjects with choroideremia, and to identify a valid and reproducible method for quantifying the area of preserved retinal pigment epithelium (RPE) in choroideremia.

Methods : Thirty-six subjects were enrolled in a natural history study of patients with choroideremia (NCT02994368). Inclusion criteria included age > 14 years, confirmed CHM mutation, and vision of 20/200 or better. Spectralis SD-OCT (Heidelberg Engineering) with a 55-degree lens was used to capture images of the RPE in the macula. Images from the same eye were co-registered and aligned with i2K Align Retina software (Dual-Align LCC) imaging. A Photoshop-based image protocol was developed to allow the adjustable measurement of RPE area. By using the quick selection tool and and image analysis function, two certified graders independently defined the FAF. The results of the 2 independent gradings of FAF images were compared to assess the reproducibility of this protocol.

Results : Results: Of the 36 patients (mean age 35.7 years, range 16-72 years) with available FAF data, 34 had finished a baseline visit, and 23 had finished a 1-year visit. For inter-grader comparison, all 114 images were included for analysis. Among them, 44 eyes of 22 patients had both baseline images and 1-year images and were included in the analysis of rate of RPE loss. The absolute difference (mean ± SD) between two independent graders for each image was 0.46 ± 0.99 mm2, and percentage difference between two independent graders was 4.01 ± 8.82%. The RPE area as determined by the 2 graders showed good agreement with an intraclass correlation coefficient of 0.980 (95% CI, 0.963-0.989; P<.001). The area of RPE in the central macula was seen to decrease significantly (P<.001) at a rate of 2.72 ± 3.86 mm2 annually, and at percentage of 7.41±5.93%.

Conclusions : FAF is considered as a surrogate biomarker of choroideremia progression. A Photoshop-based quantification of preserved RPE area in patients with choroideremia is feasible, and has a good reproducibility. Our data suggest that FAF area reduction may be measured with precision and accuracy in a feasible time frame for clinical trials in choroideremia patients.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.


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