Hypertension and the eye :

The Lancet, 380(9859), 2224-2260

To investigate circadian changes in subfoveal choroidal thickness (SFCT) and the relation to systemic factors in healthy subjects. Thirty-eight eyes of 19 healthy volunteers were enrolled. SFCT was measured by using prototype high-penetration optical coherence tomography. Intraocular pressure (IOP), systolic blood pressure (SBP), diastolic blood pressures (DBP), and heart rate (HR) were measured every 3 hours over a 24-hour period. Circadian changes in the mean arterial pressure (MAP) and mean ocular perfusion pressure (MOPP) were calculated. The difference between the maximal and minimal SFCTs was analyzed, and correlations between the SFCT and other systemic factors were evaluated. There was a significant circadian variation in SFCT (P < 0.0001). The total mean SFCT was 280.3 ± 106.1 μm. At 6 PM, the mean SFCT (271.9 ± 103.5 μm) was the thinnest and at 3 AM it was the thickest (290.8 ± 110.8 μm). The SFCTs in 32 of 38 eyes were thickest between 3 and 9 AM and in 27 of 38 eyes, thinnest between 3 and 9 PM. The mean SFCT was significantly negatively correlated with the mean SBP (R(2) = 0.59, P = 0.02) in all eyes. There were no significant correlations between the mean SFCT and the mean DBP, MAP, HR, IOP, and MOPP in all eyes. We investigated the circadian change of choroidal thickness using high-penetration optical coherence tomography in healthy volunteers. The significant diurnal change was found and the choroid was thicker at night and thinner in daytime. Fluctuations in the choroidal thickness may be related to SBP.

The retinal vasculature provides a unique window to assess vascular health noninvasively and directly in vivo. Advances in fundus photography and retinal image analysis techniques have enabled the objective and accurate assessment of quantitative retinal vascular caliber measurement. Over the last decade, large population-based studies have shown that retinal vascular calibers are associated with a wide range of subclinical (e.g. atherosclerosis, inflammation and endothelial dysfunction) and clinical cardiovascular diseases (hypertension, diabetes mellitus, stroke, kidney and heart diseases). However, while retinal image analysis provided exciting possibilities to study the pathogenesis of these diseases, its direct applicability in a clinical setting as a ‘test' to predict cardiovascular diseases is yet to be established, particularly within the context of being used as a population screening tool. Nevertheless, with continual development of retinal imaging techniques and newer understanding of the clinical significance of these retinal changes, there remains scope for the development of retinal vascular caliber measurements as a biomarker for vascular disease risk assessment in targeted areas and patient subgroups (e.g. patients with diabetes, suspected hypertension and stroke).