Hyperreflective retinal foci as predictive biomarkers for fluid resolution after dexamethasone implant treatment in retinal vein occlusions

Purpose: To evaluate intraretinal inflammatory hyperreflective retinal foci (i-HRF) as predictive biomarkers for fluid resolution after dexamethasone implant (DEX-I) treatment in patients with retinal vein occlusions. Methods: This retrospective study included 49 consecutive patients (28 central retinal vein occlusion [CRVO], 21 branch retinal vein occlusion [BRVO]) treated with DEX-I (Ozurdex, AbbVie Inc.) between 2019 and 2024. Optical coherence tomography (OCT) parameters were analysed pre- and post-treatment using artificial intelligence-assisted quantitative analysis: central retinal thickness (CRT), i-HRF count, intraretinal fluid (IRF) volume, subretinal fluid (SRF) volume, external limiting membrane (ELM) and ellipsoid zone (EZ) integrity. Results: Baseline i-HRF count significantly correlated with SRF volume reduction (r = 0.652, p < 0.001) and IRF volume reduction (r = 0.434, p = 0.003). SRF demonstrated superior resolution rates compared to IRF (92.3% vs 73.7%, p < 0.001). Patients with high i-HRF count (≥ 100) achieved 100% SRF resolution compared to 66.7% in low i-HRF group (< 60), p = 0.024. Mean CRT reduction was 350.8 ± 198.7 μm with 17.2 ± 14.3 ETDRS letters visual acuity improvement. i-HRF count decreased from 77.4 ± 29.6 to 59.8 ± 28.2 (p < 0.001), confirming anti-inflammatory efficacy. Conclusions: Baseline i-HRF count may serve as a potentially valuable biomarker of fluid resolution after DEX-I in retinal vein occlusions. Higher i-HRF counts may be associated with a greater likelihood of SRF resolution within a dexamethasone-treated cohort.