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Y. Yasuno, M. Sato, K. Kawana, F. Okamoto, S. Makita, T. Oshika, M. Miura; Visualization of Pathologies Under Retinal Pigment Epithelium in Exudative Macular Diseases by High-Penetration Optical Coherence Tomography at 1 Micrometer Wavelength. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4270.
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© ARVO (1962-2015); The Authors (2016-present)
Optical coherence tomography (OCT) has enabled the direct observation of morphological features of exudative macular diseases including age-related macular degeneration (ARMD) and polypoidal choroidal vasculopathy (PCV). Although OCT has revealed the pathologies in the retina, it is still difficult to observe the pathological features beneath the retinal pigment epithelium (RPE). This is because the standard OCT probe beam with the wavelength of 830 nm rarely penetrates through the RPE. In this study, we introduce custom-made high-penetration OCT (HP-OCT) to visualize the pathologies of exudative macular diseases beneath the RPE.
Fourteen eyes of 13 cases were prospectively involved in this study. The cases include type-I choroidal neovascularization (CNV) associated with ARMD (7 cases), type-II CNV associated with ARMD (5 cases) and PCV (1 case). Eleven of 14 eyes appeared with pigment epithelium detachment. All of the measurement protocols were approved by local ethic committee of University of Tsukuba, and Tokyo Medical University. A custom build HP-OCT was employed to this study. This new OCT uses a probe beam with the wavelength of 1060 nm, and provides deeper penetration to the choroid and higher contrast of the structures beneath the RPE than these of conventional OCT. The depth resolution is 11 um in tissue. The measurement speed is 28,000 depth scans/sec, this results in the volumetric measurement speed of 2.5 sec/volume or 5.0 sec/volume. All of the eyes were examined also by a color fundus camera, fluorescein and indocyanine green angiographies, and standard penetration OCT (SP-OCT, TOPCON 3D OCT-1000).
Six of 14 eyes showed high-contrast visualization of the pathologies beneath the RPE including CNV and PCV, which were almost invisible in the SP-OCT images. In the HP-OCT image of 1 of 14 eyes, fragmented RPE in Type-II CNV was clearly visualized, while SP-OCT did not reveal this structure. The HP-OCT of residual 7 eyes also provided significant improvement of the contrasts of the structures beneath the RPE and CNV.
This study indicates that HP-OCT provides high-contrast imaging of the pathologies beneath the RPE and CNV. This high-penetration in vivo imaging posesses marked clinical importance for the diagnosis of the exudative macular diseases.
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