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Purpose: To observe choroidal blood vessels in cases sharply demarcated with retinal pigment epithelium (RPE) atrophy at the macular area using en-face optical coherence tomography angiography (OCTA) and standard en-face optical coherence tomography (OCT)., Methods: The retrospective study included 12 eyes (8 patients; 5 men, 3 women; average age, 64.3 years) with RPE atrophy seen by ophthalmoscopy. The macular areas with normal and atrophic RPE sections were examined using en-face OCTA with an 840-nm light source (RTVue XR Avanti; Optovue Inc), which system can obtain standard en-face OCT images at identical areas. Images on en-face OCTA and standard en-face OCT were compared with each other when the segmentation range was being set as the full thickness of the choroid by the attached software., Results: Choroidal blood vessels were seen as black on standard en-face OCT images in all cases. However, the choroidal vessels on OCTA were depicted as white in the RPE atrophic area and black in the normal areas., Conclusion: Choroidal blood vessels in the normal sections of RPE were visualized in black on standard en-face OCT and OCTA with an 840-nm light source; however, those in the atrophic parts were observed as white, or with bloodstream, on OCTA images. Choroidal blood vessels cannot be evaluated accurately in commercially available OCTA systems because of blockage of light by the RPE.

Optical coherence tomography angiography (OCTA) seems not to image the choroidal blood flow pattern in the normal individual because of the OCT light attenuation. Our purpose in the current study was to visualize the large choroidal blood flow pattern after subtraction of the choriocapillaris projection artifact in normal eyes non-invasively by swept source (SS) OCTA. Sixty-one eyes of 45 individuals (19 men, 26 women) without ocular disease were examined by SS-OCTA (AngioPlex Elite 9000, Zeiss, Germany). A 12 × 12 mm macular area was scanned. Subfoveal choroidal thickness (SCT) was measured, and the choroidal blood flow pattern in a slab of 30 µm width at one-half of SCT was analyzed. In examining the choroidal blood flow pattern, a slab that was between 30 to 60 µm posterior to the retinal pigment epithelium, in which the choriocapillaris blood flow was most clearly imaged, was used for the subtraction of the projection artifacts from the choriocapillaris on the stromal area of choroid. The ratio (%) of the choroidal blood flow area in the whole choroidal region was calculated after binarization. Thirty-four eyes of 27 individuals (12 men, 15 women) were also examined by spectral domain OCTA (SD-OCTA). After the subtraction, the middle and large choroidal blood flow were clearly visible in SS-OCTA in all eyes. The mean SCT was 297 ± 61 µm, and the mean ratio of the choroidal blood flow area was 27.3 ± 8.2%, which was significantly correlated with SCT (R = 0.738, P < 0.01). SD-OCTA did not show the choroidal blood flow pattern. In conclusion, removal of the projection artifacts of choriocapillaris can make the choroidal blood flow visible in SS-OCTA of normal eyes. Because the ratio of choroidal blood flow area was correlated with SCT, the choroidal blood flow might be an important factor related to the choroidal thickness.

Purpose: To visualize choroidal blood flow in larger vessels in highly myopic eyes using a phenomenon of the projection artifact to in the sclera using optical coherence tomography angiography., Methods: The retrospective study included 92 eyes (54 patients) with greater than 8 diopters of myopia. All eyes were examined using optical coherence tomography angiography (RTVue XR Avanti; Optovue Inc, Fremont, CA). The blood flow in choroidal vessels was evaluated by attempting to directly segment the choroid and also by placing the segmentation layer behind the choroid, within the sclera. Subfoveal choroidal thickness was also measured at the same time. The authors also evaluated the 54 normal eyes (54 cases) without high myopia as a control group., Results: Segmentation artifacts occurred in 68 cases (73.9%) and precluded direct visualization of the choroidal blood flow in larger vessels. When the segmentation slab was placed posterior to the choroid within the sclera, the choroidal blood flow was visualized in 41 eyes (44.6%). The mean subfoveal choroidal thickness in eyes with visualization of choroidal blood flow was thinner than without visualization (50.3 ± 42.2 μm vs. 100.3 ± 44.4 μm, P < 0.01). Choroidal blood flow in larger vessels was imaged in no control eye., Conclusion: The choroidal vessel anatomy could be imaged by detecting flow using the projection artifact in the sclera with optical coherence tomography angiography. This technique may be useful in estimating the vascularity of the choroid.

Purpose: To evaluate the age-dependent morphologic alterations in the outer retina and choroid at the macula using swept-source optical coherence tomography (OCT)., Methods: Thirty eyes (30 normal subjects; average age, 49 years) were examined; five (age range, third-eighth decades of life) had refractive errors of ±2 diopters or less and no fundus abnormalities. An Early Treatment Diabetic Retinopathy Study (ETDRS) map of the outer retinal and choroidal thickness was constructed using swept-source OCT. The outer retinal and choroidal segmentation lines were drawn automatically, partially manually, within 6 millimeters of the macula., Results: The mean outer retinal and choroidal thicknesses in the 6-millimeter-diameter circle were 145±13 and 236±68 microns, respectively. The choroidal thickness and age were negatively (r = -0.66, P<0.01) correlated; the outer retinal thickness and age were not correlated (r = -0.16, P = 0.39). The outer retinal and choroidal thicknesses in the ETDRS map were not correlated (r = -0.13, P = 0.49) within 1 millimeter but correlated (r = 0.32, P<0.01) within 6 millimeters., Conclusions: The choroid thins with aging. The outer retina remains stable. Outer retina and choroid are correlated in the entire macula except for the center. ETDRS map can be useful for evaluation of the morphologic relationship between the outer retina and choroid.

Purpose: To examine the foveal structure and vasculature in eyes with an idiopathic epiretinal membrane (ERM). Methods: Forty-nine eyes of 48 patients with an idiopathic ERM were studied. The superficial foveal avascular zone (FAZ) was measured by optical coherence tomography angiography (OCTA; RTVue XR Avanti, Optovue Inc., Fremont, CA), and the central foveal thickness (CFT) was measured by swept source OCT (DRI-OCT, Topcon, Japan). Twenty eyes underwent vitrectomy with internal limiting membrane (ILM) peeling, and the FAZ and CFT were evaluated pre- and postoperatively. Forty-nine eyes of 49 age-matched healthy subjects were also examined as control. Results: The FAZ in eyes with an ERM was significantly smaller than that of the control eyes (0.188±0.16 mm2 vs 0.328±0.14 mm2, P<0.01). The CFT in eyes with an ERM was significantly thicker than that of control eyes (315±0.14 μm vs 193±0.14 μm, P<0.01). The size of the FAZ was strongly correlated with the CFT (ERM, R = -0.753; control, R = -0.61, both P<0.01). The postoperative size of the FAZ was not significantly different from the preoperative size (0.115 mm2 vs 0.128 mm2, P = 0.17) but the CFT was significantly thinner (370 μm vs 288 μm, P<0.01) after the vitrectomy with ILM peeling in 20 eyes. Conclusions: The results indicate that an ERM might affect the morphology and vasculature of not only the inner but also the outer retina before and after vitrectomy with ILM peeling. The FAZ area might have been affected by the ILM peeling. [ABSTRACT FROM AUTHOR]