Choroidal Hyper-Reflective Foci in Geographic Atrophy

Abstract

Purpose: The purpose of this study was to describe the presence of choroidal hyper-reflective foci (HRF) on optical coherence tomography (OCT) in patients with geographic atrophy (GA). The relationship between the presence and quantity of choroidal HRF and other clinical and imaging factors was also investigated.

Methods: A total of 40 participants (40 eyes) with GA and age-related macular degeneration (AMD) were retrospectively analyzed. OCT images were reviewed for the presence, characteristics, and localization of choroidal HRF. The amount of choroidal HRF was quantified in different choroidal layers by two different (i.e. threshold reflectivity and manual counting) methodologies. The primary outcome was to describe and quantify choroidal HRF and correlate them with GA lesion size.

Results: Structural OCT images showed that all patients had multiple hyper-reflective deposits in different layers of the choroid. These hyper-reflective deposits in the choroid were located near Bruch's membrane or the edges of the blood vessels, particularly in the Sattler's layer, and none were observed inside the vessels. Choroidal HRF exhibited variable size and shape and varying effects on the posterior signal, including shadowing or hypertransmission. Mean ± SD number of choroidal HRF per B-scan was 21.5 ± 15.4 using the threshold reflectivity methodology and 25.1 ± 16.0 using the manual counting methodology. A significant correlation between the untransformed GA size and number of HRF was found, considering both quantitative strategies.

Conclusions: Hyper-reflective dots in the choroid of subjects with GA may be readily identified with structural OCT. These HRF might represent a natural component of the choroid that becomes more visible due to the absence of the retinal pigment epithelium.

Figure 1.

Representative optical coherence tomography (OCT) B-scan of a patient with geographic atrophy (GA). OCT B-scan (left) showing the presence of hyper-reflective foci (HRF) within the choroid. A magnified visualization of specific regions is reported in the right column. The structural OCT image shows multiple hyper-reflective deposits in different layers of the choroid, which mostly colocalize with regions with atrophy. These hyper-reflective deposits in the choroid were located near Bruch's membrane (green asterisk) or the edges of the blood vessels (arrowheads). The dimensions and shape of HRF showed significant variability, with a predominant smaller and round appearance near Bruch's membrane, whereas larger and oval shapes were observed in deeper layers.

Figure 2.

Representative optical coherence tomography (OCT) B-scan of a patient with geographic atrophy (GA). OCT B-scan (left) showing the presence of choroidal hyper-reflective foci (HRF). A magnified visualization of the foveal region is reported in the right column. Choroidal HRF are not limited to regions with retinal pigment epithelium (RPE) atrophy, as they were visualizable also in regions with conserved RPE (orange asterisk). Hyper-reflective deposits are localized near Bruch's membrane (orange asterisk) and within the choroidal stroma (orange arrowhead).

Figure 3.

Representative optical coherence tomography (OCT) B-scan of a patient with geographic atrophy (GA). OCT B-scan (left) showing the presence of choroidal hyper-reflective foci (HRF). A magnified visualization of the foveal region is reported on the right. Hyper-reflective deposits are localized near Bruch's membrane (orange asterisk) and within the choroidal stroma (orange arrowhead). Choroidal HRF exhibited varying effects on the posterior signal, including shadowing or hypertransmission, the latter characteristic causing a barcode effect within the underlying sclera (orange asterisks).

Figure 4.

Representative optical coherence tomography (OCT) B-scans of a patient with intermediate AMD. OCT B-scans (left) showing the presence of choroidal hyper-reflective foci (HRF). A magnified visualization of the temporal region is reported on the right. Hyper-reflective deposits are localized near Bruch's membrane and within the choroidal stroma (orange asterisks).

Figure 5.

Scatterplots illustrating correlations between the number of choroidal hyperreflective foci (HRF) and the untransformed geographic atrophy (GA) size. (Upper scatterplots) Relationship between the untransformed GA size and average number of choroidal HRF obtained using the threshold reflectivity methodology in the choriocapillaris (CC; ρ = 0.748 and P < 0.0001 and CC; ρ = 0.727 and P < 0.0001), Sattler's (ρ = 0.495 and P = 0.001) (ρ = 0.491 and P = 0.001), and Haller's (ρ = 0.386 and P = 0.014) (ρ = −0.351 and P = 0.026) layers, and whole choroid (ρ = 0.679 and P < 0.0001) (ρ = 0.672 and P < 0.0001). (Lower scatterplots) Relationship between the untransformed GA size and average number of choroidal HRF obtained using the manual counting methodology in the CC (ρ = 0.727 and P < 0.0001), Sattler's (ρ = 0.491 and P = 0.001), and Haller's (ρ = −0.351 and P = 0.026) layers, and whole choroid (ρ = 0.672 and P < 0.0001).