Drusen Type Impacts Choroidal Impairment in Nonexudative AMD

Eyes with nonexudative age-related macular degeneration (AMD) and subretinal drusenoid deposits (SDD) have greater flow voids in the choriocapillaris and thinner peripapillary choroidal thickness (CT) than eyes with AMD and drusen or pachydrusen, researchers found in a study published in Retina. They completed this research since previous researchers had investigated the features of macular choroid but not the peripapillary CT and choriocapillaris flow void features on optical coherence tomography angiography (OCT-A).

They retrospectively reviewed the medical records of 95 patients with AMD (29 with pachydrusen, 33 with drusen and 33 with SDD) who were diagnosed between June 2016 and December 2018 at Korea University Medical Center. The researchers excluded eyes with glaucoma, optic nerve disorders, high myopia, retinal vascular diseases, or history of vitreoretinal surgery, laser therapy or intravitreal anti-vascular endothelial growth factor treatment.

OCT with color fundus photography (CFP) was used to classify 1 eye per patient by drusen type. The researchers obtained the mean peripapillary CT values of the 4 quadrants. The macular and peripapillary OCTA examinations covered a 3 mm x 3 mm area centered on the macular or optic disc. To investigate the choriocapillaris flow voids, en face choriocapillaris images were used to adjust for attenuation of signals by overlying structures. That image was then binarized so the researchers could select dark regions representing flow voids.

Using the Duncan test, they found the pachydrusen group possessed the greatest macular and peripapillary CT (221.54 mm ± 64.47 mm and 114.30 mm ± 39.34 mm) compared with the drusen group (163.63 mm ± 64.08 mm and 93.47 mm ± 39.07 mm) and SDD group (95.33 mm ± 28.87 mm and 56.06 mm ± 11.64 mm) (all P <.05). The mean macular flow void areas of the SDD (57.07% ± 6.16%) and drusen (58.30% ± 6.98%) groups were greater than that of the pachydrusen group (50.09% ± 5.77%; P <.05). The mean peripapillary flow void area of the SDD group (55.38% ± 6.65%) was greater than that of the drusen (49.11% ± 9.11%) and pachydrusen (45.47% ± 8.06%, all P <.05). In the SDD group, peripapillary flow void area was associated with mean macular CT (P =.025) and peripapillary CT (P =.005), and multivariate analysis indicated that mean peripapillary CT was associated with mean peripapillary flow void area (P =.029). Peripapillary flow void area was associated with age in the drusen group (P =.021) and mean CT ( P =.023), and, as multivariate analysis found, age was associated with mean peripapillary flow void area (P =.031).

“Eyes with SDDs demonstrated a thinner choroid and greater flow void area, suggesting that these eyes are experiencing diffuse hypoperfusion of the choriocapillaris and choroidal abnormalities both inside and outside the macula,” the research says. “Knowledge of the different features of the peripapillary choroid from eyes with each drusen phenotype may be helpful in understanding the role of the choroid in the pathogenesis of these eyes.”

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