The nature of focal areas of hyperfluorescence or 'hot spots' imaged with indocyanine green angiography

Purpose: To clarify the frequency and nature of ICG angiographic "hot spots" seen in patients with neovascular age-related macular degeneration (ARMD). Methods: A consecutive series of newly diagnosed patients with neovascular ARMD and fluorescein angiographic evidence of occult choroidal neovascularization (occult CNV) was imaged with ICG angiography. Eyes with ICG angiographic "hot spots" were identified and further classified. A hot spot was defined as any area of abnormal hyperfluorescence, in the mid to late stages of ICG angiography, measuring less than 1 disk area in size. Results: From a total of 190 patients (220 eyes) with neovascular ARMD, 30 patients and 34 eyes (16%) with hot spots were identified. Hot spots were noted to be of three distinct patterns: polypoidal choroidal neovascularization (polypoidal CNV) in 21 of 34 eyes, or 62%; retinal angiomatous proliferation (RAP) in 11 of 34 eyes, or 30%; and focal occult CNV in 2 of 34 eyes, or 8%. Conclusions: A focal area of intense hyperfluorescence or so-called hot spot seen on ICG angiography in neovascular ARMD is due to one of three possible forms of neovascularization: most frequently polypoidal CNV, less commonly RAP, and infrequently nonspecific, focal occult CNV. Since neovascular ARMD may be caused by different types of neovascularization, each with distinct clinical manifestations, natural course, visual prognosis, and response to treatment, it is important to identify the precise nature of hot spots to establish an accurate diagnosis and, when appropriate, a specific form of management.