OCTA reveals retinal vascular damage in patients diagnosed with renal hypertension, offers early diagnostic insights
The findings suggest that retinal microvessel damage may occur due to renal hypertension (RH).
(Image credit: AdobeStock/Richman Photo)
A team of researchers in China conducted a study to identify abnormalities in retinal and conjunctival vascular density using optical coherence tomography angiography (OCTA) techniques in patients with renal hypertension (RH).
According to the study, published in Scientific Reports, from October 2022 to October 2023, the researchers selected a cohort of 16 patients diagnosed with RH, comprising a total of 32 eyes, from the Department of Nephrology at the First Affiliated Hospital of Nanchang University. Concurrently, a control group of 16 healthy individuals, carefully matched for demographic and clinical characteristics, was recruited from volunteers at the Ophthalmology Research Center and designated as the healthy control (HC) group.1
According to the researchers, OCTA was employed to assess the superficial vascular plexus (SVP) and deep vascular plexus (DVP) of the macular retina in both eyes of the participants. They conducted a comparative analysis between the RH and HC groups, focusing on parameters including superficial and deep retinal microvascular density (MIR), macrovascular density (MAR), and total microvascular density (TMI).
The study utilized several segmentation methods to evaluate deviations in retinal blood vessel density. These included the central annuli segmentation method (C1–C6), the hemispheric segmentation method (SL, IL, SR, IR), and the Early Treatment Diabetic Retinopathy Study (ETDRS) segmentation approach (S, I, L, R). Additionally, the researchers examined the association between retinal blood vessel density and TMI in conjunctival capillaries.1
According to researchers the findings suggest that retinal microvessel damage may occur due to RH, as evidenced by significantly lower blood vessel density in the superficial and deep retina of individuals in the RH group compared to HCs group. Additionally, the higher positive probability ratios observed in the deep SL region and superficial C2 region suggest a potentially greater diagnostic significance for detecting retinal microvascular alterations induced by RH. Furthermore, it was observed that the deep TMI region exhibited a robust positive association with conjunctival capillary density, whereas no significant correlation was found between the superficial TMI area and patients with RH. Therefore, the alteration of retinal microvascular OCTA is expected to be one of the criteria for adjuvant diagnosis of renal hypertension.
The researchers noted the measurement of retinal microcirculation using OCTA allows for rapid and non-invasive assessment. Parameters such as vascular density (VD), foveal avascular zone (FAZ), and radial peripapillary capillary (RPC) network are utilized to evaluate microvascular changes in the retina and choroid.
According to researchers, OCTA is emerging as a vital noninvasive imaging modality capable of detecting subtle changes in capillary structure, offering early warning signs of ischemia and hypoxia. These changes often precede observable alterations in arterioles and venules, making OCTA an invaluable tool for early intervention in vascular-related diseases. This technology also holds promise for diagnosing systemic conditions such as coronary heart disease (CHD) and chronic kidney disease (CKD).
One of the most notable applications of OCTA is its potential role in identifying reductions in retinal and choroidal vascular density associated with coronary artery stenosis. The researchers noted these changes may serve as an early marker for CHD, potentially reducing the risk of myocardial infarction (MI). Unlike spectral-domain OCT (SD-OCT), which measures structural changes, OCTA evaluates blood vessel density and flow hemodynamics, adding a new dimension to noninvasive cardiovascular risk assessment.1
In hypertensive retinopathy (RH), OCTA reveals significant microvascular changes. These alterations often involve microvascular obstructions and reduced macular retinal thickness, likely driven by peripheral vascular spasm and the activation of the renin-angiotensin-aldosterone system (RAAS). In this study, patients with RH demonstrated a marked reduction in vascular density across specific retinal regions, including SL, SR, IL, S, I, L, and C1–C3, compared to healthy controls. These findings suggest that the temporal retinal arteriole may be particularly susceptible to occlusion, potentially affecting trophic nerve fibers.
Additionally, this study highlights correlations between retinal vascular density and systemic diseases. Reduced density in the superficial vascular plexus (SVP) and deep vascular plexus (DVP) has been observed in patients with CKD and those at risk for acute kidney injury (AKI). These findings align with previous research, underscoring OCTA’s utility in identifying retinal microvascular changes as potential predictors of systemic disease progression. The technology demonstrated high diagnostic capacity, with likelihood ratios nearing 1.0 for specific macular regions, suggesting its value in detecting retinal microangiopathy.
Despite its promise, the researchers acknowledgein the study several limitations . The relatively small sample size may limit generalizability, and confounding factors, such as medication use, could influence results. Furthermore, distinguishing between RH caused by kidney disease and essential hypertension remains challenging, as both conditions contribute to retinal vascular alterations. Longitudinal studies involving larger cohorts are needed to establish the dynamic monitoring of macular microvessel density changes as RH progresses.
“OCTA has also deepened our understanding of how RH progresses within the retinal vasculature,” the researchers wrote. “The central retinal artery (CRA), which supplies blood to the inner retinal layers, branches into the superficial and deep capillary plexuses. Our findings suggest that RH progression involves reduced perfusion, particularly in the temporal regions of the retina, potentially indicating preferential damage to these areas.”
The broader implications of OCTA extend beyond the retina. For instance, conjunctival capillary density correlates with deep retinal vascular parameters, further supporting its role in evaluating systemic vascular health. One study revealed that more than 70% of patients with hypertension and CKD exhibited hypertensive retinopathy, emphasizing the close interplay between ocular and systemic vascular health.
Moreover, the researchers noted the use of OCTA to assess microvascular changes offers significant clinical benefits, including early detection of retinopathy and systemic conditions before severe complications arise. By identifying reductions in vascular density at both superficial and deep retinal layers, OCTA provides clinicians with critical information to guide early interventions.
Conclusion
OCTA represents a transformative advance in the diagnosis and management of RH and associated systemic diseases.
“This study underscores its value in detecting early microvascular changes, facilitating timely interventions, and improving disease prognosis,” the investigators concluded. “While further research is necessary to overcome current limitations, the integration of OCTA into routine clinical practice could revolutionize the management of retinal and systemic vascular conditions, reducing the burden of vision loss and systemic morbidity.”
