Purpose: The purpose of this study was to analyze the angiographic (confocal scanning laser ophthalmoscopy technology) and corresponding (eye-tracked) spectral-domain optical coherence tomography (SD-OCT) features and to propose a classification for the progressive phases establishing retinal-choroidal anastomosis (RCA).
Methods: We reviewed all consecutive eyes with RCA that underwent Heidelberg Retina Angiograph angiography and tracked Spectralis SD-OCT at the University Eye Clinic of Creteil between September 2007 and March 2009.
Results: Twenty-six eyes of 23 patients (8 men and 15 women, aged 70-88 years) showing RCA naïve to any treatment were included for analysis. In 6 of 7 eyes showing a discrete focal hyperfluorescence (focal staining), the corresponding (eye-tracked) SD-OCT scan showed a focal retinal pigment epithelium (RPE) erosion ("erosion sign") over a small, localized RPE elevation (which appeared filled with a hyperreflective material); in 7 of 8 eyes showing a typical "hot spot" in the late angiographic frames (focal leakage) and absence of a serosanguineous pigment epithelium detachment, the corresponding (eye-tracked) SD-OCT scan showed a focal RPE break leaving 2 free RPE flaps ("flap sign") at the level of a small, localized RPE elevation. In 10 of 11 eyes showing a typical hot spot in the late angiographic frames and presence of a serosanguineous pigment epithelium detachment, the corresponding (eye-tracked) SD-OCT scan showed, at the level of a large serosanguineous RPE detachment, a focal funnel-shaped RPE joining (kissing) an inverted focal funnel-shaped inner neuroepithelium ("kissing sign").
Conclusion: An early neovascularization (a discrete focal hyperfluorescence) arising from the choroid initially simply erodes the basement membrane/RPE (erosion sign; Phase 1) and later breaks the basement membrane/RPE (flap sign), infiltrating first into the outer retina forming an early RCA (Phase 2, a typical hot spot without a serosanguineous pigment epithelium detachment) and later into the inner retina (kissing sign) forming an established RCA (Phase 3, a typical hot spot with a serosanguineous pigment epithelium detachment).