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Joy Willemse, Maximilian Gr�fe, Aleid van de Kreeke, Frank D Verbraak, Yvonne de Jong, Johannes de Boer; Subretinal fibrosis detection using polarization sensitive optical coherence tomography. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3442. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Subretinal fibrosis (SRF) causes permanent loss of vision in neovascular age-related macular degeneration (wAMD) and other retinal diseases. No reliable diagnostic tool has yet been established to detect SRF. In this study, a new metric based on polarization-sensitive OCT (PS-OCT) is used to distinguish a fibrotic lesion from a non-fibrotic lesion in patients with retinal diseases, including wAMD, high myopia and multifocal choroiditis.
A home-built swept-source PS-OCT setup with a center wavelength of 1060 nm was used to scan 29 eyes with retinal pathology. Retinal pathology included lesions suspected of fibrosis, lesions suspected to be non-fibrotic, and lesions which were not judgeable based on existing diagnostic tools. PS-OCT imaging included intensity, cumulative phase retardation, and local birefringence images. Additionally, a new metric - the optic axis uniformity (OAxU) - was used to visualize birefringence with higher sensitivity based on the optic axis of the birefingence in scattering material. This metric is defined as the length of the spatially averaged (≈ 50 x 60 µm, depth x width) normalized optic axis, and varies between 0 and 1.
14 eyes showed high phase retardation signal within the lesion, 13 did not show high phase retardation and 2 were unjudgeable. High OAxU (> 0.8) was found in all suspected fibrotic lesions. Figure 1 shows two fibrotic lesions from different patients suspected to show fibrosis. Inside the lesions, the cumulative phase retardation shows a column-like signal, suggesting that there is a birefringent structure present. Local birefringence images showed good contrast in cases with strong birefringence (Figure 1c). However, in some patients, local birefringence did not show a significant signal inside the lesion (Figure 1e). In comparison, OAxU images provided a stronger contrast for weak birefringent tissue, and enabled more exact localization of the birefringent structure. An additional birefringent signal of scleral tissue can be seen in the lowest visible regions.
Different metrics were compared for their applicability to detect and localize subretinal fibrosis based on PS-OCT. The use of optic axis uniformity (OAxU) images stood out as most sensitive and robust. This new metric could provide a novel biomarker for clinical research to monitor the development of AMD and to assess the response of the tissue to treatment.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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