Optical coherence tomography angiography of the optic nerve head and macula after achieving target intraocular pressure

Background Optical coherence tomography angiography (OCTA) offers a precise, noninvasive visualization of the microvascular changes. Purpose The aim of this study was to evaluate the peripapillary and vascular alterations in primary open-angle glaucoma (POAG) or ocular hypertension patients after achieving target intraocular pressure (IOP) by medications. Patients and methods This prospective cohort study evaluated 40 eyes (of 22 patients) with medically controlled POAG or ocular hypertension. The patients underwent swept-source OCTA at baseline, and at 3 and 6 months after achieving the target IOP. High-quality 4.5×4.5 mm scans centered on the optic nerve head were captured, strictly including images with a signal strength index of 40 or greater. The primary outcome measures were the longitudinal changes in the vessel density (VD) and blood flow within the optic nerve head and macula, alongside the peripapillary and choroidal structural alterations. The secondary outcome measures included the changes in visual acuity and the monthly IOP measurements. Results The medical treatment achieved a mean IOP reduction of 51.3%. Brimonidine+Dorzolamide/Timolol achieved a significantly more reduction in IOP (58.4%) than specific monotherapies like Brimonidine alone (46.1%) or Dorzolamide/Timolol (45.7%, P =0.001). The OCTA revealed a significant reduction in the superior peripapillary superficial VD from a baseline median (interquartile range) of 63.2% (53.6–65.6%) to 43.35% (34.4–61.6%) at 6 months ( P <0.001), alongside significant decreases in the macular VD in both the superior [49.7% (47.2–53.1%) to 44.9% (42.0–47.0%), P <0.001] and the inferior [48.1% (45.2–50.5%) to 40.7% (37.5–46.5%), P <0.001] regions. The retinal nerve fiber layer thickness and the foveal avascular zone showed no statistically significant changes over the 6 months of follow up ( P =0.801 and 0.08, respectively). Conclusion The medical treatment lowered the IOP in POAG, correlating with a significantly reduced superficial VD and stable structural integrity of the retinal nerve fiber layer and the foveal avascular zone.