SD-OCT vs FA in diabetic retinopathy: a sensitivity-specificity tradeoff in detecting intraretinal macroaneurysms

To evaluate and compare the sensitivity and specificity of spectral-domain optical coherence tomography (SD-OCT) versus fluorescein angiography (FA) in detecting intraretinal macroaneurysms (IMAs) in patients with diabetic retinopathy (DR) in real-life clinical practice.

A retrospective, single-center study was conducted at the ophthalmology department of Pitié-Salpêtrière Hospital, Sorbonne University, from 2019 to September 2022. Fifty-eight eyes from 29 DR patients (mean age 50.2 ± 14.6 years) underwent comprehensive ophthalmological evaluation including slit-lamp examination, MultiColor confocal fundus imaging, and multimodal imaging with FA and SD-OCT (Heidelberg Spectralis HRA + OCT). IMAs were defined as aneurysmal dilations ≥ 150 μm. Because no independent gold standard (e.g., histology) was available, the consensus interpretation across both modalities served as the reference standard, and the resulting incorporation dependency is acknowledged as a limitation. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) with 95% confidence intervals (CIs) were calculated for each modality, with McNemar's test comparing sensitivities. Cohen's kappa assessed inter-reader agreement.

SD-OCT demonstrated significantly higher sensitivity (92.3%; 95% CI: 79.1-98.4) than FA (48.7%; 95% CI: 32.4-65.2) for IMA detection (p < 0.05). Conversely, FA exhibited higher specificity (63.2%; 95% CI: 38.4-83.7) than SD-OCT (47.4%; 95% CI: 24.4-71.1). The PPV and NPV were 78.3% and 75.0% for SD-OCT, and 73.1% and 37.5% for FA. Inter-reader agreement was moderate to substantial (κ = 0.69 for SD-OCT; κ = 0.51 for FA).

In this cohort, SD-OCT showed superior sensitivity but lower specificity than FA for detecting IMAs in patients with DR. This suggests SD-OCT is highly effective for identifying potential IMAs based on structural characteristics, while FA remains valuable for confirming activity based on leakage. The non-invasive nature and high detection rate of SD-OCT support its role as a primary tool in the routine diagnostic workflow for IMAs in DR. Further prospective, multi-center studies are warranted.