High resolution Fourier-domain optical coherence tomography of retinal angiomatous proliferation

Abstract

Purpose: To study the anatomic details of retinal angiomatous proliferation (RAP) in patients with age-related macular degeneration (AMD) using high-resolution Fourier-domain optical coherence tomography (Fd-OCT) and its three-dimensional reconstructions.

Methods: A Fd-OCT instrument was used to image five patients clinically diagnosed with RAP. A series of 100 raster-scanned B-scans centered over the macula was registered and rendered as a three-dimensional volume. These retinal structures were analyzed for anatomic details of the RAP lesions.

Results: The RAP lesion could be identified within the retina on Fd-OCT in all five cases. Fd-OCT images of the first four cases revealed areas of intraretinal neovascularization (IRN) in the deep retina adjacent to a pigment epithelial detachment (PED). There was neovascular proliferation anteriorly and posteriorly through a break in the retinal pigment epithelium (RPE). In three of the four cases, Bruch membrane remained intact. There was no identifiable choroidal neovascularization (CNV). The fifth case had both subretinal and sub-RPE neovascular membranes without a PED.

Conclusion: Fd-OCT provides unprecedented in vivo detail of the anatomy of RAP lesions that nearly resembles histologic specimens. This study suggests that the initial neovascular process in RAP can originate either within the retina or in the sub-RPE space.

Fig. 1

Yannuzzi classification system of retinal angiomatous proliferation. A, Stage I: intraretinal neovascularization. B, Stage II: subretinal neovascularization with a retinal-retinal anastomosis. C, Stage II: subretinal neovascularization with a serous pigment epithelial detachment. D, Stage III: choroidal neovascularization with a vascularized pigment epithelial detachment and a retinal-choroidal anastomosis.

Fig. 2

Gass classification system of retinal angiomatous proliferation. Stage 1. Atrophy of the outer retina (arrow) with approximation of retinal capillaries and occult Type 1 subretinal pigment epithelium choroidal new vessels. Stage 2. Anastomosis (arrow) of retinal capillaries with Type 1 new vessels. Stage 3. Proliferation of Type 2 new vessels in the subretinal space (arrow). SSRN, subsensory retinal choroidal neovascularization. Stage 4. Activation of Type 1 vessels causing serous retinal pigment epithelium (RPE) detachment (arrows). Stage 5. Compound piggyback Type 2-Type 1 cicatricial disciform lesion with overt CRA (arrow).

Fig. 3

Patient 1. A, Red free fundus photograph shows the retinal angiomatous proliferation lesion just inferior to the fovea with an intraretinal hemorrhage. The dotted lines correspond to the Fourier-domain optical coherence tomography (Fd-OCT) images presented. B, Fluorescein angiogram showing diffuse hyperfluorescence with pooling consistent with a large pigment epithelial detachment (PED). C, Grayscale rendition of Fd-OCT B-scan (small dashed line on fundus photo) shows highly reflective areas that correspond to the deep angiomatous changes and intraretinal neovascularization with intraretinal edema. D, False-color rendition of same B-scan as in C. E, Grayscale rendition Fd-OCT B-scan (large dashed line on fundus photograph) shows a large PED with proliferation from the deep retina through a break in the retinal pigment epithelium (RPE). The anterior extent of the proliferation approaches the inner retina via a retina-retinal anastomosis. No identifiable sub-RPE hyper-reflectivity suggestive of a choroidal neovascular complex is seen. F, False-color rendition of same B-scan as in E. Note that the sub-RPE extension of the hyperreflective lesion is slightly better visualized in false color.

Fig. 4

Patient 2. A, Color fundus photograph of retinal angiomatous proliferation (RAP) shows intraretinal hemorrhages overlying a grayish mound of deep angiomatous changes just superior to the fovea. The dotted lines correspond to the Fourier-domain optical coherence tomography (Fd-OCT) images presented. B, Fluorescein angiogram shows intense hyperfluorescence of the RAP lesion with ill-defined zone of leakage around the angiomatous changes. C, Indocyanine green angiogram shows a focal area of intense hyperfluorescence (“hot spot”). D, Fd-OCT image (small dashed line) shows multifocal areas of high reflectivity corresponding to the angiomatous changes. Adjacent to the RAP lesions are areas of intraretinal edema. There is tenting up of the retinal pigment epithelium (RPE) under the neovascular proliferation, forming a pocket of subretinal fluid. Note that Bruch’s membrane is intact. E, Fd-OCT B-scan (large dashed line) shows the extension from the intraretinal neovascularization through a break in the RPE to an early lesion in the sub-RPE space. Note that Bruch’s membrane is still intact. F, Three-dimensional reconstruction of the macula with cut through the RAP complex. The B-scans are taken from the x plane.

Fig. 5

Patient 3. A, Color photograph shows a retinal angiomatous proliferation (RAP) lesion with intraretinal hemorrhages superior to and inferior to the fovea. The dotted lines correspond to the Fourier-domain optical coherence tomography (Fd-OCT) images presented. B, Fluorescein angiogram shows ill-defined zone of hyperfluorescence pooling into an associated pigment epithelial detachment (PED). C, Fd-OCT image (small dashed line) shows a large PED with several areas of high reflectivity in the deep retina and intraretinal cystic edema overlying a PED. Underneath the retinal pigment epithelium (RPE), there appears to be a sub-RPE highly reflective lesion. Bruch’s membrane remains intact. D, Fd-OCT (large dashed line) shows the extension of the highly reflective lesion into the sub-RPE space through the RPE break. Bruch’s membrane appears intact. Note the shadowing effects from the angiomatous changes overlying the RPE break.

Fig. 6

Patient 4. A, Red-free photograph of retinal angiomatous proliferation (RAP) shows an area of intraretinal hemorrhage superior to the fovea with a large pigment epithelial detachment (PED). Note the ring of circinate exudation. The dashed lines correspond to the Fourier-domain optical coherence tomography (Fd-OCT) images presented. B, Fluorescein angiogram shows leakage around the angiomatous proliferation. C, Fd-OCT (small dashed line) image shows intraretinal edema with pinpoint hyper-reflectivities representing the angiomatous changes. There is proliferation into the subretinal space with thickening of the retina. The retinal pigment epithelium shows signs of discontinuity and early detachment. Bruch’s membrane is not clearly visualized here. D, Fd-OCT (large dashed line) through areas of exudation reveal dense, intense reflectivity with shadowing corresponding to the exudation.

Fig. 7

Patient 5. A, Red-free photograph shows the intraretinal hemorrhages with a retinal vessel diving into a mound of angiomatous change. The dashed lines correspond to the Fourier-domain optical coherence tomography (Fd-OCT) images presented. B, Fluorescein angiogram shows an occult-like choroidal neovascularization with diffuse leakage. C, Fd-OCT shows a subretinal pigment epithelium (RPE) (Type 1) lesion under the fovea (small dashed lines) with a break in Bruch’s membrane. No pigment epithelial detachment (PED) or intraretinal edema is seen. There is subretinal fluid. D, Fd-OCT image (large dashed lines) shows a subretinal (Type 2) lesion adjacent to pinpoint areas of hyper-reflectivity corresponding to the angiomas. Again, there is no PED or intraretinal edema. Note the presence of an intact RPE beneath the type II lesion.