QUANTITATIVE ASSESSMENT OF INTRARETINAL HYPERREFLECTIVE FOCI IN PATIENTS WITH INTERMEDIATE AGE-RELATED MACULAR DEGENERATION

Abstract

Purpose : The presence of intraretinal hyper-reflective foci (HRF) due to migrating retinal pigment epithelium (RPE) has already been associated with age related macular degeneration (AMD) progression. We retrospectively reviewed en-face OCT images of intermediate AMD patients to evaluate the correlation between HRF quantity and progression to advanced AMD after one year.

Methods : A series of 6x6 mm macular cube scans (Cirrus HD-OCT) from 114 eyes of 114 patients were reviewed. Five consecutive en-face slabs from the inner limiting membrane to the inner surface of RPE, each representing 20% of the retinal thickness, were analyzed after enhancing contrast with the instrument software. HRF were automatically segmented (and manually-refined) using ImageJ software and confirmed by inspection of corresponding B-Scans. The five slabs were combined and the area of HRF was measured in the whole image (HRF_TOT), and in the central 3mm (HRF_3mm) and 5mm (HRF_5mm) areas (Figure). Inter-operator repeatability of HRF measurements was tested in 20 eyes. Overall results were correlated with the development of choroidal neovascularization (CNV) and/or RPE atrophy after one year of follow-up, using Spearman coefficients.

Results : HRF measurements showed good inter-operator repeatability with intra-class correlation coefficients of 0.894 (95% confidence interval: 0.878-0.934), 0.873 (0.843-0.927) and 0.869 (0.841-0.931) for HRF_3mm, HRF_5mm and HRF_TOT respectively. At baseline, 58 patients had presence of HRF (50.8%). Among the whole cohort, 9 patients developed CNV (7.9%) and 37 (32.4%) developed RPE atrophy after one year of follow-up. A good correlation was found between HRF measurements and progression to either RPE atrophy or CNV: R=0.610 (p<0.001) for HRF_3mm, R=0.622 (p<0.001) for HRF_5mm and R=0.614 (p<0.001) for HRF_TOT. Correlations were still significant with progression to atrophy alone (0.545 (p<0.001), 0.560 (p<0.001) and 0.556 (p<0.001) for HRF_3mm, HRF_5mm and HRF_TOT respectively), but not for progression to CNV alone, possibly due to the low event rate of CNV (i.e. underpowered).

Conclusions : The amount of HRF in patients with intermediate AMD correlated with the 1-year risk of AMD progression, in particular with the development of RPE atrophy. Quantification of macular HRF using en-face OCT may have a potential clinical use in evaluating patients’ prognosis.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.