Looking into the Eyes to See the Heart of Chronic Kidney Disease Patients

Abstract

In patients with chronic kidney disease (CKD), the main cause of morbidity and mortality is cardiovascular disease (CVD). Both coronary artery calcium scoring by computed tomography (CT) and optical coherence tomography (OCT) are used to identify patients at increased risk for ischemic heart disease, thereby indicating a higher cardiovascular risk profile. Our study aimed to investigate the utility of these techniques in the CKD population. In patients with CKD, OCT was used to measure the choroidal thickness (CHT) and the thickness of the peripapillary retinal nerve fiber layer (pRNFL). A total of 127 patients were included, including 70 men (55%) with an estimated glomerular filtration rate (eGFR) of 39 ± 30 mL/min/1.73 m². Lower pRNFL thickness was found to be related to high-sensitivity troponin I (r = -0.362, p < 0.001) and total coronary calcification (r = -0.194, p = 0.032). In a multivariate analysis, pRNFL measurements remained associated with age (β = -0.189; -0.739--0.027; p = 0.035) and high-sensitivity troponin I (β = -0.301; -0.259--0.071; p < 0.001). Severe coronary calcification (Agatston score ≥ 400 HU) was related to a worse eGFR (p = 0.008), a higher grade of CKD (p = 0.036), and a thinner pRNFL (p = 0.011). The ROC curve confirmed that the pRNFL measurement could determine the patients with an Agatston score of ≥400 HU (AUC 0.638; 95% CI 0.525-0.750; p = 0.015). Our study concludes that measurement of pRNFL thickness using OCT is related to the markers associated with ischemic heart disease, such as coronary calcification and high-sensitivity troponin I, in the CKD population.

Keywords: CKD; cardiac disease; choroid; coronary disease; retinal nerve; troponin.

Figure 1

Chorioretinal structures. (a) Left up image: A circular green grid is centered over the optic nerve and consists of one concentric ring 3.5 mm in diameter around the optic nerve head. The blue line represents the projection of the center of this ring to the fovea. The ring is divided into six quadrants: temporal (T), temporal-superior (TS), temporal-inferior (TI), nasal (N), nasal-superior (NS), nasal-inferior (NI), and global (G). Scale bars: 200 μm. Right up image: Cross-sectional scan presented in a horizontal diagram in which the extreme ends of the diagram represent the temporal retinal nerve fiber, blue line is the retinal nerve fiber layer thickness, red line is the internal limiting membrane, green line corresponds to the position of the red asterisk shown in left up and right down image. Left down image: The study map divides the macula into six subfields and the global in the middle. Right down image: The quantification of the thickness of the retinal ganglion cell axons where white would be above normal, green is within normal range, yellow is borderline, and red is clearly reduced compared with normal. (b) Left image: OCT of fundus image, Right image is corresponding OCT Image below the green arrow inside the green box. Choroidal thickness was measured at three locations on the macula (yellow lines): N = 2000 μm nasal to the fovea, F = subfoveal, and T = 2000 μm temporal to the fovea. Scale bars: 200 μm.

Figure 2

The relationship between pRNFL and severe coronary disease. (a) Patients with severe global coronary calcification (≥400 HU) had a thinner pRNFL (89 ± 17 μm) than those with non-severe global coronary calcification (<400 HU), who had a pRNFL of 97 ± 13 μm (* p = 0.011). (b) ROC curve showing that pRNFL thickness could indicate those patients with an Agatston score of ≥400 HU (AUC 0.638; 95% CI 0.525–0.750; p = 0.015). Blue line—ROC curve, red line—baseline.