Optical coherence tomography characteristics of Intraretinal hyperreflective foci associated with diabetic retinopathy and age-related macular degeneration

Abstract

Purpose : Intraretinal hyperreflective foci (IHRF) are important biomarkers on optical coherence tomography (OCT) in diabetic retinopathy (DR) and age-related macular degeneration (AMD). The etiology of IHRF is presumed to differ between DR and AMD eyes, but their exact origins remain controversial. The study objective was to compare IHRF in eyes with DR vs AMD quantitatively.

Methods : A retrospective analysis was performed on 54 treatment-naive eyes (27 DR and 27 AMD). 9 macular B-scans (Spectralis OCT; 6x6 mm; ART=9; separated by 666 microns) were evaluated in all cases. IHRF was defined as features within the neurosensory retinal layers of ≥ 3 pixels in size and reflectivity similar to or greater than that of the retinal pigment epithelium (RPE) band. IHRF was semi-automatically segmented using Image J (Figure 1). Mean reflectivity (MR), maximum diameter, circularity index (Cir), area, and the angle between the greatest linear dimension (GLD) and the horizontal were computed for each lesion. The MR was normalized using the vitreous and retinal nerve fiber layer (RNFL) reflectivities as dark and bright reference standards, respectively. The presence or absence of a posterior shadow and the axial location were also assessed. Two groups were compared using independent t-tests and chi-square tests.

Results : A total of 1149 IHRF (1051 in DR and 98 in the AMD group) were identified, with a mean of 38.92±35.53 lesions in DR eyes compared to 3.62±3.83 in AMD eyes. Table 1 shows the characteristics of each cohort and IHRF lesions. The mean area of lesions was greater in DR eyes but AMD lesions had higher reflectivity. In AMD eyes, the angle of GLD was greater, suggesting that IHRF was more horizontally elongated. 89% of AMD IHRF were located below the inner border of the outer nuclear layer, compared to 56% of DR eyes (P<0.001). In AMD eyes, 59% of IHRF had posterior shadows compared to 68% in DR eyes.

Conclusions : DR and AMD IHRF display significant differences, with DR lesions typically larger and less reflective than AMD lesions. The prognostic importance of these characteristics of IHRF requires further study.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1. Intraretinal hyper-reflective foci (IHRF) on OCT B-scans from eyes with DR (A1, A2) and AMD (B1, B2), with segmented IHRF highlighted in the lower panels (red; A2, B2)

 

Table 1. IHRF characteristics of eyes with DR and AMD