Optical coherence tomography angiography (OCTA) may be a valuable tool in detecting choriocapillaris (CC) impairment surrounding the geographic atrophy (GA) margin, according to a recent study in Retina.
A team of Italian researchers analyzed CC vessel density around GA secondary to dry age-related macular degeneration using OCTA over a six-month period in 2016-2017. Investigators compared CC vessel density within 500μm of the GA margin, and outside the margin as controls, in patients at the Medical Retina and Imaging Unit of University Vita-Salute in Milan. The researchers obtained images and compared vessel density in a sample area surrounding the GA margin, rated as hyperautofluorescent on fundus autofluorescence, to a similar area rated as isoautofluorescent.
The study included 50 eyes of 29 patients with a mean GA area of 9.43 ± 5.08mm and a mean subfoveal choroidal thickness of 164 ± 73μm. Researchers found choriocapillaris vessel density surrounding GA margin as detected by OCTA revealed a significant impairment compared with control CC outside GA margin (0.317 ± 0.083 vs. 0.461 ± 0.054), which was even greater in patients with foveal involvement. Investigators also noted mean vessel density in hyperautofluorescent areas was significantly lower compared with isoautofluorescent areas (0.242 ± 0.112 vs. 0.327 ± 0.130). Additionally, the study reported a positive correlation between vessel density surrounding GA margin and subfoveal choroidal thickness.
“Optical coherence tomography angiography discloses CC impairment surrounding GA margin,” the researchers said in their paper. “Such CC impairment at GA margin seems to precede retinal pigment epithelium alterations at fundus autofluorescence. Optical coherence tomography angiography could be a new valuable tool for detecting CC alterations and to evaluate potential therapeutic responses in clinical studies.”
Because fundus autofluorescence did not reveal atrophic retinal pigment epithelium in the same area, the data seemed to support the theory that the damage of CC vascular layer may precede the retinal pigment epithelium atrophy, researchers added. Together with previous studies, this implicates that other mechanisms unrelated to the retinal pigment epithelium disruption may be implicated in the CC impairment, despite an intimate relationship, they said.
|Sacconi R, Corbelli E, Carnevali A, et al. Optical coherence tomography angiography in geographic atrophy. Retina. 2018; 38(12):2350-55.|