Fig. 9.9 This patient received 12 Gy of external beam radiation for choroidal neovascularization and had a cessation of exudation. During follow-up, the patient showed a resumption of

growth of the neovascularization that had growth characteristics similar to polypoidal choroidal vasculopathy. This condition is called radiation-associated choroidal neovasculopathy [31]

monotonically increasing amount of contrast between one area of staining and the surrounding choroid.

–The third main use of ICG angiography is to diagnose polypoidal choroidal vasculopathy (Figs. 9.7 and 9.8), which is a slow growing variant of CNV that has interconnecting vascular channels and aneurismal dilations at the outer border of the lesion. Some patients have developed a polypoidal-like change after having external beam radiation for CNV (Fig. 9.9).

It is common for both classic and occult neovascu-

larization to be present in one lesion. In that case, the areas of the relative types are used to characterize the lesion. If a lesion is 75% classic and 25% occult, the lesion is said to be predominantly classic. If the lesion is 25% classic and 75% the lesion could presumably be called predominantly occult, but this would bring up the difficultly of a lesion that is 25% classic and 75% blood. Since blood is not occult disease, this lesion could not be called predominantly occult. Therefore lesions with classic CNV occupying less than 50% of the total area are termed minimally classic lesions. This type of classification was useful during the era of photodynamic therapy for CNV, but is not particularly useful today.

9.13Retinal Pigment Epithelial Detachments

Although PEDs can occur in the context of non-neo- vascular AMD, most PEDs are related to CNV. The

relationship can occur in two main ways. First PEDs with a notch usually have occult CNV in the notch. Additional signs for the presence of occult CNV include blood or other exudative material in the PED, irregular elevation of the PED, subretinal blood or lipid adjacent to the PED, or the fluorescein angiographic findings of adjacent fibrovascular PED, late leakage of undetermined source, or irregular, heterogeneous filling of the PED. Choroidal neovascularization is difficult to image through a PED because of the melanin in the RPE as well as the rapid, intense build-up of fluorescence in the PED from fluorescein leakage. For this reason, studies of the treatment of CNV have often excluded patients with large PEDs. One strategy to characterize the extent of the CNV is to perform ICG angiography, which is neither limited by melanin pigment in the RPE or by leakage into the cavity of the PED. ICG angiography of notched PEDs commonly identifies the region involved with CNV. ICG angiography of large PEDs without a notch frequently shows an underlying plaque of CNV.

Using EDI-OCT the internal characteristics of fibrovascular PEDs were investigated. Many PEDs occurring in the context of AMD have evidence of CNV growing up the back surface of the RPE. Contraction of this fibrovascular material has been associated with the formation of RPE tears (Figs. 9.10 and 9.11).

In eyes with RPE tears, the detached monolayer of RPE scrolls toward the neovascularization, leaving a bared area of choroid exposed. It is theorized that

Fig. 9.10 This patient had choroidal neovascularization above the level of the retinal pigment epithelium (RPE, open arrowhead) and below the RPE (closed arrowhead) associated with pigment epithelial detachment (PED, the top of which is shown by the arrow, top) as visualized by enhanced depth imaging (EDI) optical coherence tomography (OCT). The middle

and bottom illustrations are successive sections taken inferiorly to the section illustrated at the top of the Figure. Note the increasing elevation of the PED. At the back surface of the PED is an accumulation of hyperreflective material contiguous with the layer of sub-RPE neovascularization (arrows in each section) (From Spaide [32])

this area is eventually repopulated by RPE cells, which often are completely devoid of pigment. During fluorescein angiography, the bared area is hyperfluorescent early, and depending on the amount of underlying CNV or by the seal of the scrolled RPE over any underlying CNV may show leakage. The

scrolled region of RPE is particularly dark, and blocks the underlying fluorescence. On occasion the scrolled area of RPE has been termed “doubly hypofluorescent.” This same scrolled RPE contains more lipofuscin in its vertical summation, and therefore appears doubly autofluorescent.

Fig. 9.11 (a) Intraand subretinal hemorrhage overlying a PED (upper left). Early during fluorescein angiography the PED (upper right) showed generalized decreased fluorescence with two areas of increased fluorescence, one contiguous with the retinal hemorrhage and a second area inferiorly. This patient was seen emergently because of a 3-day history of visual acuity change. The two lines correspond to sections examined with the EDI OCT. (Middle left) Later in the fluorescein angiogram, there was a generalized increase in fluorescence within the PED. (Middle right) Early during the indocyanine green (ICG) angiographic sequence, there were two areas of increased fluorescence

that corresponded to what was seen in the fluorescein angiogram. Since the pigmentation in the RPE is thought not to represent a major impediment to the passage of near-infrared light used in ICG angiography, the hyperfluorescent areas were considered to represent actual neovascularization and not transmission defects through the RPE. (Bottom left) The areas of hyperfluorescence increased in size in the midphase of the ICG angiogram (arrowheads). In the late phase of the ICG angiogram (bottom right), a larger underlying area of hyperfluorescence was visualized, consistent with a larger placoid area of choroidal neovascularization (arrows)

9.14Retinal Vascular Contribution to the Exudative Process

Although historic atlases of retinal disease have shown retinal vascular anastomosis with choroidal neovascularization, for many years, this condition was not mentioned. Over the last decade, interest in this condition increased and numerous theories developed about the anatomic structure of the anastomic connection. In a minority of patients, the retinal vessels appear to dive down and initiate vascular proliferation independent of the choroidal vasculature. These pro-

liferating vessels often occur in patients with focal hyperpigmentation. Other signs of retinal vascular proliferation are retinal vascular telangiectasis, dot hemorrhages within the retina, right angle veins and arteries, PEDs and microaneurysms. This condition was first described by Hartnett and coworkers as deep retinal vascular anomalous complexes (RVAC) [33]. It has been described by later authors as retinal angiomatous proliferation or RAP [34]. Still later Gass and colleagues [35] proposed that these patients have a chorioretinal anastomosis with occult choroidal neovascularization or ORCA. While the proposed