Visualization of sub-retinal pigment epithelium morphologies of exudative macular diseases by high-penetration optical coherence tomography.

PURPOSE: To evaluate the clinical significance of the newly developed long-wavelength probe optical coherence tomography (LP-OCT) for the diagnosis of exudative macular diseases.
METHODS: Fourteen eyes of 13 participants were prospectively enrolled in the study. There were seven type I and five type II choroidal neovascularization (CNV) cases associated with age-related macular degeneration and idiopathic neovascularization and one case of polypoidal choroidal vasculopathy (PCV). A custom-built LP-OCT based on swept-source OCT (SS-OCT) technology was used. This new OCT uses a probe beam with a wavelength of 1060 nm that provides deeper penetration into the choroid and higher image contrast to the structures beneath the retinal pigment epithelium (RPE) and pathologic tissues than does conventional OCT. The depth resolution is 10.4 microm in tissue and the measurement speed is 28,000 depth scans/s. All the eyes were also examined by standard short wavelength probe OCT (SP-OCT). The image contrasts of the LP- and SP-OCT were qualitatively evaluated and analyzed by Wilcoxon's paired signed rank test and Spearman's rank correlation test.
RESULTS: In 10 of 14 eyes, high-contrast visualization of the diseases beneath the RPE, CNV, or fibrin was attained. These diseases were almost invisible in the SP-OCT images. The LP-OCT of the remaining eyes also revealed significant improvement in the image contrasts beneath the RPE and CNV. Qualitative evaluation of the image contrasts and subsequent statistical test indicated statistically significant improvement in the image penetration to the choroid of LP-OCT to that of SP-OCT.
CONCLUSIONS: LP-OCT provided significant improvement in the image contrast of exudative macular diseases.