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M. Miura, A.E. Elsner, M.C. Cheney, M. Osako, T. Iwasaki, M. Usui; Imaging Polarimetry in Epiretinal Membrane . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4063.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate a polarimetry method to detect the retinal blood vessels in the region of an epiretinal membrane (ERM).
We prospectively examined 24 eyes of 24 patients (age 65.3 ± 7.3 years) with ERM at the macula, and 24 eyes of 24 normal subjects (age 65.0 ± 10.4 years). Polarimetry images were digitized using a GDx–N (Laser diagnostic technologies), with scanning polarized light at 780 nm. Depolarized light images, parallel polarized light images, and average reflectance images were computed. We compared each polarimetry image and a 514 nm scanning laser ophthalmoscope image for visualization of retinal blood vessels. For each case, one retinal artery and one retinal vein were selected at 5 deg from fovea to obtain a vessel profile of intensity data. We computed Michelson contrast, C = (Lmax – Lmin)/(Lmax + Lmin), where Lmax is the average grayscale from the two most peripheral points on either side of the vessel profile, and Lmin was grayscale at the darkest point.
In all eyes with ERM, retinal vessels were clearly visible in the depolarized light images. In other images, retinal vessels were considerably obscured by ERM. The contrasts of retinal arteries in eyes with ERM were 0.23 ± 0.09 (depolarized), 0.10 ± 0.05 (parallel), 0.12 ± 0.05 (average), and 0.06 ± 0.04 (514 nm). The contrasts of retinal veins in eyes with ERM were 0.20 ± 0.09 (depolarized), 0.08 ± 0.06 (parallel), 0.11 ± 0.06 (average), and 0.05 ± 0.04 (514 nm). The contrasts of retinal arteries in normal eyes were 0.28 ± 0.09 (depolarized), 0.21 ± 0.07 (parallel), 0.23 ± 0.07 (average), and 0.33 ± 0.09 (514 nm). The contrasts of retinal veins in normal eyes were 0.25 ± 0.07 (depolarized), 0.21 ± 0.07 (parallel), 0.22 ± 0.07 (average), and 0.30 ± 0.08 (514 nm). In normal eyes, the orders of contrasts at retinal arteries and retinal veins were: 514 nm > depolarized > average > parallel (P < 0.0001, ANOVA). In ERM, the orders of contrasts at retinal arteries and retinal veins were: depolarized > average > parallel > 514 nm (P < 0.0001, ANOVA). For both arteries and veins, there was a significant interaction between type of image and normal vs. ERM patient (P < 0.0001, ANOVA).
Depolarized light images are an effective tool for visualizing retinal vessels in eyes with ERM.
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