Trimester-resolved longitudinal OCTA analysis of retinal and choriocapillaris microvascular changes in healthy, gestational diabetes, and preeclampsia pregnancies.

PURPOSE: To characterize trimester-specific retinal, choroidal, and optic nerve head (ONH) microvascular adaptations during pregnancy using optical coherence tomography angiography (OCTA), and to distinguish physiological remodeling in healthy pregnancy (HP) from pathological alterations associated with gestational diabetes mellitus (GDM) and preeclampsia (PE).

METHODS

This prospective, true longitudinal case-control study included 69 pregnant women (23 GDM, 22 PE, 24 HP) and 31 age-matched healthy nonpregnant controls (HC). OCTA imaging was performed at the 10th, 24th, and 30th gestational weeks in the same individuals, ensuring within-subject assessment of trimester-related microvascular changes. Standardized 6 × 6 mm macular scans were used to quantify vessel density (VD) and perfusion density (PD) in the superficial and deep capillary plexuses (SCP, DCP), choriocapillaris, choroid, ONH, radial peripapillary capillaries (RPC), and lamina cribrosa. Foveal avascular zone (FAZ) metrics were also recorded.

RESULTS

HP demonstrated a biphasic microvascular pattern characterized by increased SCP and DCP VD and PD in the first trimester, followed by progressive attenuation toward late gestation, with near-normalization by the third trimester. In contrast, GDM and PE exhibited exaggerated early hyperperfusion that transitioned into a steeper and earlier decline, particularly affecting the DCP, ONH, and RPC. PE was associated with more pronounced peripapillary and ONH involvement, whereas GDM showed earlier and more diffuse macular capillary changes. FAZ area increased with advancing gestation in all pregnancy groups without between-group differences.

CONCLUSIONS

True longitudinal, trimester-based OCTA reveals distinct adaptive and pathological trajectories, supporting its value for early detection and risk stratification in high-risk pregnancies.