Aspects of optical coherence tomography angiography and dye angiography in the diagnosis of type 1 choroidal neovascularization secondary to pachychoroid

Type 1 choroidal neovascularization secondary to pachychoroid is characterized by the presence of type-1 neovascularization within a thicker choroid accompanied by dilated Haller veins, without any indications of age-related macular degeneration or other degenerative disorders. The aim of this report was to review and describe the latest technical aspects of optical coherence tomography angiography (OCTA) and dye angiography in the diagnosis of type 1 choroidal neovascularization (CNV) secondary to pachychoroid present in literature. The methods section of the study involved a literature review using advanced research in the major online databases. A total of 477 cases of pachychoroidal neovasculopathy were identified from literature and included in the study. OCTA showed the following findings: overlying RPE abnormalities, double layer sign, central choroid thickness over 270 microns, pachyvessels, dilated Haller vessels, compression of choriocapillaris and type 1 CNV in absence of signs of age-related macular degeneration (AMD). Fluorescein angiography (FA) and ICG are considered useful tools for the diagnosis of type 1 CNV in pachychoroid in association with OCTA, which is considered the main instrument for the diagnosis. OCTA is considered to be the most appropriate and specific examination for the detection of type 1 neovascularization associated with pachychoroid showing greater sensitivity for type-1 CNV detection in relation to FA and ICG alone.