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Maximilian G. O. Gräfe, Aleid van de Kreeke, Yvonne de Jong - Hesse, Frank D Verbraak, Johannes De boer; Subretinal fibrosis detection with polarization sensitive OCT. Invest. Ophthalmol. Vis. Sci. 2018;59(9):290.
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© ARVO (1962-2015); The Authors (2016-present)
Subretinal fibrosis arises in the late stages of exudative age-related macular degeneration (AMD) , despite treatment with anti-VEGF drugs. Optical coherence tomography (OCT) has become a standard tool in clinical practice but provides poor contrast for differentiation between fibrotic and non-fibrotic tissue. Polarization sensitive OCT measures the changes in the polarization state due to birefringent tissues. Fibrotic tissues are birefringent due to their aligned fiber structure which makes it uniquely detectable by polarization sensitive (PS) techniques. We investigate the sensitivity of PS-OCT to detect subretinal fibrosis in patients with and without suspected subretinal fibrosis.
A swept source PS-OCT system at 1050 nm with in-house developed analysis software in Matlab [Braaf et al., Biomed Opt Expr 5 (8) 2014] was used to acquire and process data from patients diagnosed with exudative AMD and suspected subretinal fibrosis as well as patients with non-fibrotic lesions and healthy volunteers as negative controls. Improvements were implemented on the system for a better phase stability and on the processing software for an improved stability in the calculation of birefringent properties such as cumulative double pass phase retardation (DPPR), optic axis orientation and diattenuation.
Fig. 1 shows the structural and DPPR image of a single B-scan of a healthy subject. The DPPR is minimal in the retina and choroid, only reaching large values in the sclera at the bottom of the image. In contrast, figure 2 shows a patient with a suspected subretinal fibrotic lesion corresponding with the location of the large (yellow) DPPR values in the retina well above the choroid. The signal vanished at the left side of the image due to beam clipping.
We showed that fibrotic tissue is clearly indicated when imaged with PS-OCT and shows a birefringent effect quantitatively similar to scleral tissue in vivo. Both tissues can additionally be distinguished by depth information. This makes PS-OCT potentially a well suited technique to discriminate subretinal fibrosis from other tissues.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Fig. 1 a) structural image (intensity) and b) DPPR of a B-scan through the fovea of a healthy subject. Scan size: approximately 6 mm
Fig. 2 a) structural image (intensity) and b) DPPR of a B-scan of a lesion of suspected SRF. Scan size: approximately 6 mm
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