Review of retinal angiomatous proliferation or type 3 neovascularization

LA Yannuzzi, KB Freund, BS Takahashi - Retina, 2008 - journals.lww.com
LA Yannuzzi, KB Freund, BS Takahashi
Retina, 2008journals.lww.com
Retinal angiomatous proliferation (RAP), recently termed “type 3 neovascularization,”
represents a distinct form of neovascularization in age-related macular degeneration. On the
basis of analysis of data for an expanded recent series of patients with RAP and a review of
the ophthalmic literature, it is proposed that the vasogenic process in RAP patients may
originate from the retinal or choroidal circulation or both, leading ultimately to an identical
vascular complex or a retinal–choroidal anastomosis. The retinal involvement distinguishes …
Retinal angiomatous proliferation (RAP), recently termed “type 3 neovascularization,” represents a distinct form of neovascularization in age-related macular degeneration. On the basis of analysis of data for an expanded recent series of patients with RAP and a review of the ophthalmic literature, it is proposed that the vasogenic process in RAP patients may originate from the retinal or choroidal circulation or both, leading ultimately to an identical vascular complex or a retinal–choroidal anastomosis. The retinal involvement distinguishes RAP from other forms of neovascularization and introduces specific clinical, prognostic, and therapeutic implications.
Several years ago, we assimilated several previous observations to describe a neovascular form of age-related macular degeneration (AMD) that appeared to originate from within the neurosensory retina. We believed that intraretinal neovascularization originating from the inner retinal circulation produced a surrounding telangiectatic compensatory response to accommodate an increase in vascular perfusion. 1 The clinical appearance of the earliest manifestations was termed “stage I”(Fig. 1). As these vessels evolved, they appeared to extend beneath the neurosensory retina to become subretinal neovascularization (SRN) termed “stage II”(Fig. 2) and eventually merged with the choroidal circulation proliferating beneath the retinal pigment epithelium (RPE) as choroidal neovascularization (CNV) or stage III to form a retinal–choroidal anastomosis (Fig. 3). The original interpretation of this angiogenic sequence was based on reports of atypical forms of neovascularization in AMD, 2–4 particularly with the use of combined fluorescein angiography and indocyanine green (ICG) angiography and the first-generation optical coherence tomography (OCT) imaging system (OCT-1, Carl Zeiss, Meditec, Inc., Dublin, CA, USA) available at that time. 5 Because the initial retinal vascular changes were presumed to be neovascularization combined with compensatory telangiectatic change, we termed this variant “retinal angiomatous proliferation”(RAP). Given that this concept challenged traditional dogma that involved a long-held belief that all neovascularization in AMD originated from the choroidal circulation, it is not surprising that other investigators have questioned this hypothesis. 6, 7 They have suggested that occult choroidal vessels actually initiate the vasogenesis, proliferating through atrophic RPE to infiltrate the neurosensory retina without detaching either of these tissue layers. 6, 7
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