Retinal neurovascular changes in chronic kidney disease

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

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.

Associations between Chronic Kidney Disease and Thinning of Neuroretinal Layers in Multiethnic Asian and White Populations

Purpose

To evaluate the relationships between chronic kidney disease (CKD) with retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness profiles of eyes in Asian and White populations.

Design

Cross-sectional analysis.

Participants

A total of 5066 Asian participants (1367 Malays, 1772 Indians, and 1927 Chinese) from the Singapore Epidemiology of Eye Diseases Study (SEED) were included, consisting of 9594 eyes for peripapillary RNFL analysis and 8661 eyes for GCIPL analysis. Additionally, 45 064 White participants (87 649 eyes) from the United Kingdom Biobank (UKBB) were included for both macular RNFL analysis and GCIPL analysis.

Methods

Nonglaucoma participants aged ≥ 40 years with complete data for estimated glomerular filtration rate (eGFR) were included from both SEED and UKBB. In SEED, peripapillary RNFL and GCIPL thickness were measured by Cirrus HD-OCT 4000. In UKBB, macular RNFL and GCIPL were measured by Topcon 3D-OCT 1000 Mark II. Chronic kidney disease was defined as eGFR < 60 ml/min/1.73 m2 in both data sets. To evaluate the associations between kidney function status with RNFL and GCIPL thickness profiles, multivariable linear regression with generalized estimating equation models were performed in SEED and UKBB data sets separately.

Main Outcome Measures

Average peripapillary and macular RNFL thickness and macular GCIPL thickness.

Results

In SEED, after adjusting for age, gender, ethnicity, systolic blood pressure, antihypertensive medication, diabetes, hyperlipidemia, body mass index, smoking status, and intraocular pressure, presence of CKD (β = -1.31; 95% confidence interval [CI], -2.37 to -0.26; P = 0.015) and reduced eGFR (per 10 ml/min/1.73 m2; β = -0.32; 95% CI, -0.50 to -0.13; P = 0.001) were associated with thinner average peripapillary RNFL. Presence of CKD (β = -1.63; 95% CI, -2.42 to -0.84) and reduced eGFR (per 10 ml/min/1.73 m2; β = -0.30; 95% CI, -0.44 to -0.16) were consistently associated with thinner GCIPL in SEED (all P < 0.001). In UKBB, after adjusting for the above-mentioned covariates (except ethnicity), reduced eGFR (per 10 ml/min/1.73 m2; β = -0.06; 95% CI, -0.10 to -0.01; P = 0.008) was associated with thinner macular RNFL and CKD (β = -0.62; 95% CI, -1.16 to -0.08; P = 0.024) was associated with thinner average GCIPL.

Conclusion

We consistently observed associations between CKD and thinning of RNFL and GCIPL across Asian and White populations' eyes. These findings further suggest that compromised kidney function is associated with RNFL and GCIPL thinning.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Association of preoperative retinal microcirculation and perioperative outcomes in patients undergoing congenital cardiac surgery

BACKGROUND

Microcirculatory dysfunction is associated with increased morbidity and mortality in cardiac surgery patients. This study aimed to investigate the association between preoperative retinal microcirculation evaluated using optical coherence tomography angiography (OCTA) and perioperative outcomes in patients with congenital heart disease (CHD).

METHODS

This prospective, observational study was performed from May 2017 to January 2021. OCTA was used to automatically quantify the vessel density (VD) of the superficial capillary plexus, deep capillary plexus (DCP), and radial peripapillary capillary (RPC) preoperatively. The primary outcome was excessive postoperative bleeding, defined as bleeding volume > 75th percentile for 24-hour postoperative chest tube output. The secondary outcome was composite adverse outcomes, including one or more operative mortalities, early postoperative complications, and prolonged length of stay. The association between retinal VD and outcomes was assessed using Poisson regression.

RESULTS

In total, 173 CHD patients who underwent cardiac surgery were included (mean age, 26 years). Among them, 43 (24.9%) and 46 (26.6%) developed excessive postoperative bleeding and composite adverse outcomes, respectively. A lower VD of DCP (odds ratio [OR], 1.24; 95% confidence interval [CI], 1.08-1.43; P = 0.003) was independently associated with excessive postoperative bleeding, and a lower VD of RPC (OR, 1.97; 95% CI, 1.08-3.57; P = 0.027), and DCP (OR, 2.17; 95% CI, 1.08-4.37; P = 0.029) were independently associated with the postoperative composite adverse outcomes.

CONCLUSION

Preoperative retinal hypoperfusion was independently associated with an increased risk of perioperative adverse outcomes in patients with CHD, suggesting that retinal microcirculation evaluation could provide valuable information about the outcomes of cardiac surgery, thereby aiding physicians in tailoring individualized treatment.

Macular Microvascular Perfusion Status in Hypertensive Patients with Chronic Kidney Disease

To compare retinal microvascular perfusion between the eyes of hypertensive patients with and without chronic kidney disease (CKD), the vessel density (VD) and fractal dimension (FD) of the superficial (SVP) and deep retinal vascular plexus (DVP) were analyzed on 6 × 6 mm fovea-centered optical coherence tomography angiography (OCTA) images of patients with hypertension. The retina was divided into an inner ring (IR) and outer ring (OR) according to the Early Treatment of Diabetic Retinopathy Study grid. The glomerular filtration rate (GFR) was determined and CKD was diagnosed (GFR < 60 mL/min/1.73 m2). Ninety-six eyes from 52 patients with hypertension were included in this analysis. Twenty patients (n = 37 eyes) were diagnosed with CKD. The mean age was 69 ± 11.7 years and 60.4 ± 9.2 years in the CKD group and in the control group, respectively. The univariate model revealed a significant difference in VD between patients without and with CKD in the superficial IR (0.36 ± 0.03 vs. 0.34 ± 0.04, p = 0.03), the superficial OR (0.35 ± 0.02 vs. 0.33 ± 0.04, p = 0.02), the deep OR (0.24 ± 0.01 vs. 0.23 ± 0.02, p = 0.003), and the FD in the SVP (1.87 ± 0.01 vs. 1.86 ± 0.02, p = 0.02) and DVP (1.83 ± 0.01 vs. 1.82 ± 0.01, p = 0.006). After adjusting for age and sex, these differences did not remain statistically significant. Similar results were observed for the FD in the SVP and DVP. In our cohort, patients with hypertension and CKD did not differ from patients without CKD in regard to microvascular perfusion status in the macular area as assessed using OCTA.

Retinal Neurodegeneration and Visual Acuity Decline in Patients with Chronic Kidney Disease

INTRODUCTION

Chronic kidney disease (CKD) has been associated with accelerated retinal neurodegeneration. The purpose of this study is to evaluate the association between retinal neurodegeneration and the best-corrected visual acuity (BCVA) decline in patients with CKD.

METHODS

Post hoc analysis of two prospective studies. Patients with CKD stage ≥ 3 were enrolled. Macular thickness, peripapillary retinal nerve fiber layer (pRNFL) thickness, and macular ganglion cell complex (GCC) thickness were measured by optical coherence tomography. Eyes were classified into three groups: Group 1, no GCC defect; Group 2, GCC defect confined to parafoveal area; and Group 3, GCC defects extending beyond the parafoveal area. Each group was matched for age, sex, axial length, lens status, and cataract grading.

RESULTS

A total of 120 eyes (40 eyes in each group) from 120 patients (age 63.0 ± 10.3 years) were included. The logMAR BCVA was 0.076 ± 0.101, 0.100 ± 0.127, and 0.196 ± 0.191 in Group 1, 2, and 3, respectively. Group 3, but not Group 2, had a significantly worse BCVA than Group 1. In simple linear regression, parafoveal inner retinal thickness, pRNFL thickness, presence of pRNFL defect, GCC thickness, GCC global loss volume, GCC focal loss volume, and GCC defect extending beyond parafoveal area were associated with BCVA. Central subfield retinal thickness (CRT), parafoveal full retinal thickness, and parafoveal outer retinal thickness were not associated with BCVA. In backward stepwise linear regression, age and GCC defects extending beyond the parafoveal area were factors associated with BCVA. Moreover, GCC defect extending beyond parafoveal area was connected with worse BCVA in both phakic and pseudophakic subgroups.

CONCLUSIONS

GCC defect extending beyond parafoveal area could be an independent biomarker associated with decreased BCVA in patients with CKD. However, macular thinning measured by CRT or parafoveal full retinal thickness might have low discriminative power in determining BCVA.

Association of chorioretinal thickness with chronic kidney disease

OBJECTIVE

To assess retinal and choroidal thickness changes in chronic kidney disease (CKD) patients using spectral domain optical coherence tomography (SD-OCT).

BACKGROUND

CKD is a devastating health trouble. The eye and the kidney share similar structural and genetic pathways, so that kidney disease and ocular disease may be closely linked. OCT is a precise, fast method for high-definition scanning of the retina and choroid.

PATIENTS AND METHODS

A cross sectional study was conducted at Menoufia University Hospital ophthalmology department on 144 eyes of 72 CKD patients divided into 3 groups according to the stage of CKD as follows: group 1: CKD stage 1-2, with Glomerular Filtration Rate (GFR) > 60 ml/min/1.73m² group 2: CKD stage 3, GFR 30-59 ml/min/1.73m² and group 3: CKD stage 4-5, eGFR < 29 ml/min/1.73m². All patients underwent full ophthalmologic examination followed by OCT assessment of retinal, retinal nerve fiber layer (RNFL) and choroidal thickness.

RESULTS

Retinal and choroidal thickness were reduced in group 2 (CKD stage 3) and group 3 (CKD stage 4-5) compared with group 1 (CKD stage 1-2). The reduction was more severe in group 3 than group 2. RNFL thickness did not differ between groups. A thinner retina and choroid were associated with an elevated serum C-reactive protein (CRP) concentration, and greater degrees of proteinuria.

CONCLUSION

Chorioretinal thinning in CKD is associated with a lower eGFR, a higher CRP, and greater proteinuria. Further studies, in a large scale of patients, are needed to detect whether these eye changes reflect the natural history of CKD.

Co-occurrence of chronic kidney disease and glaucoma: Epidemiology and etiological mechanisms

As the histology, physiology, and pathophysiology of eyes and kidneys show substantial overlap, it has been suggested that eye and kidney diseases, such as glaucoma and chronic kidney disease (CKD), may be closely interlinked. We review the relationship between CKD and various subtypes of glaucoma, including primary open-angle glaucoma, primary angle- closure glaucoma, normal tension glaucoma, pseudoexfoliation syndrome, and several glaucoma endophenotypes. We also discuss the underlying pathogenic mechanisms and common risk factors for CKD and glaucoma, including atherosclerosis, the renin-angiotensin system, genes and genetic polymorphisms, vitamin D deficiency, and erythropoietin. The prevalence of glaucoma appears elevated in CKD patients, and vice versa, and the literature points to many intriguing associations; however, the associations are not always confirmed, and sometimes apparently opposite observations are reported. Glaucoma and CKD are complex diseases, and their mutual influence is only partially understood.

Accelerated Peripapillary Retinal Nerve Fiber Layer Degeneration in Patients With Chronic Kidney Disease: A 2-Year Longitudinal Study

Purpose

To evaluate the longitudinal changes in the peripapillary retinal nerve fiber layer (pRNFL) in patients with chronic kidney disease (CKD).

Methods

In this prospective cohort study, the CKD group consisted of patients with CKD stage ≥ 3. Age-matched healthy controls were enrolled at a 1:4 ratio. Spectral-domain optical coherence tomography was used to measure the pRNFL at baseline, 1 year, and 2 years. Within-group longitudinal changes and between-group comparisons were performed using linear mixed models.

Results

Overall, 152 patients with CKD and 40 controls were included (mean ages, 62.8 ± 9.1 years vs. 63.0 ± 9.3 years; P = 0.931). The CKD group showed faster loss of pRNFL than the control group (-0.87 µm/y vs. -0.26 µm/y; P = 0.004). Subgroup analysis found that the rate of pRNFL change was -0.41 µm/y in stage 3a CKD, -0.74 µm/y in stage 3b, -0.98 µm/y in stage 4/5, and -1.38 µm/y in end-stage renal disease. Multiple linear regression analysis revealed that CKD stage (coefficient = -0.549; 95% confidence interval [CI], -0.966 to -0.131; P = 0.010), hypertension (coefficient = -1.557; 95% CI -3.013 to -0.101; P = 0.036), and rim area (coefficient = -1.505; 95% CI, -2.940 to -0.070; P = 0.040) were factors associated with the pRNFL change over 2 years.

Conclusions

Patients with CKD experienced faster pRNFL loss than healthy controls did. Severity of CKD, hypertension, and rim area were independent factors associated with the loss of pRNFL.

Translational Relevance

This study contributes to our understanding of retinal neurodegeneration in normal aging and in patients with chronic kidney diseases.

Changes of retinal ganglion cell complex after vitrectomy in rhegmatogenous retinal detachment patients and its correlation with inflammatory blood biomarkers

Purpose

To compare retinal ganglion cell complex (GCC) parameters between rhegmatogenous retinal detachment (RRD) eyes and normal contralateral eyes after vitrectomy and to evaluate their correlation with inflammatory blood markers.

Methods

We investigated 25 eyes that underwent vitrectomy due to RRD. Venous blood samples were collected from all participants before 08:00 a.m. on the second day of admission after a 12-hour fast for blood counts. The differences of retinal structure between RRD and contralateral eyes were compared 1 week postoperatively.

Results

Focal loss volume (FLV) (2.009 ± 1.286)% was significantly increased compared with the contralateral eyes (p <  0.001). Monocyte-to-high-density lipoprotein was significantly positively correlated with GCC thickness parameters, and negatively correlated with FLV and global loss volume (GLV). Postoperative best-corrected visual acuity was negatively correlated with GLV (p = 0.039, R² = 0.172).

Conclusion

Retinal ganglion cells (RGCs) loss might present early postoperatively in RRD eyes, and was associated with systemic inflammation. RGCs loss might affect postoperative vision.

Retinal Optical Coherence Tomography Angiography Parameters Between Patients With Different Causes of Chronic Kidney Disease

Background

Chronic kidney disease (CKD) is a major public health issue because of the rising number of patients with the risk of progression to end-stage renal disease. The retinal micro-vasculatures provide a unique window to assess systemic microcirculation. Optical Coherence Tomography Angiography (OCTA) parameters may provide a non-invasive method for systemic correlation. This research aims to compare the association of OCTA parameters in different causes of CKD.

Methods

This is a single-center cross-sectional study on patients with CKD at the Universiti Kebangsaan Malaysia Medical Centre over 2 years. Patients with CKD were divided into three groups: DM group (diabetic CKD), HPT group (hypertensive CKD), and AG group (autoimmune-related glomerulonephritis CKD). The OCTA parameters, namely, the foveal avascular zone (FAZ), vascular density (VD), perfusion density (PD), and macular volume (MV), were measured and recorded using OCTA. Blood and urine analyses were taken as the patient's CKD profile. The demographic data, the OCTA parameters and the CKD profiles, were analyzed using SPSS version 23.

Results

The right eyes of 232 patients were included. The median age of the control and CKD subjects were 36 and 61 years old respectively. The proportion of the subjects under the control, diabetes mellitus (DM), HPT, and AG group were 30.6, 53.4, 5.6, and 10.4% respectively. There was no significant difference in FAZ, but there is a significant difference in the VD, PD, and MV between the control and CKD groups. There was a statistically significant difference between the three different causes of CKD in VD and PD (p < 0.001, p = 0.001, respectively). When compared with the control group for VD and PD, there were significant differences between the DM-control group (p < 0.001, p < 0.001) even when the age variable was considered, but no significant difference when comparing the HPT-control and the AG-control. There was a significant correlation between age, FBS, and HbA1c with VD and PD. There was no significant association between CKD profile and FAZ.

Conclusion

Our study showed the meaningful reduction of VD and PD in patients with diabetes and CKD. However, the use of OCTA to screen or predict CKD in patients living with diabetes mellitus, hypertension, or autoimmune nephritis was not shown to be useful.

Association of Long Non-Coding RNA Growth Arrest-Specific 5 Genetic Variants with Diabetic Retinopathy

The aim of this work was to appraise the potential associations of single nucleotide polymorphisms (SNPs) of long non-coding RNA growth arrest-specific 5 (GAS5) with diabetic retinopathy (DR) in a diabetes mellitus (DM) population. Two loci of the GAS5 SNPs (rs55829688 and rs145204276) were genotyped via TaqMan allelic discrimination in 449 non-DR patients and 273 DR subjects. The SNP rs145204276 Del/Del showed a significantly higher distribution in the DR group compared to the non-DR group (AOR: 2.487, 95% CI: 1.424–4.344, p = 0.001). During subgroup analyses, the non-proliferative diabetic retinopathy (NPDR) subgroup demonstrated a significantly higher ratio of the SNP rs145204276 Del/Del (AOR: 2.917, 95% CI: 1.574–5.406, p = 0.001) and Ins/Del + Del/Del (AOR: 1.242, 95% CI: 1.016–1.519, p = 0.034) compared to the non-DR population, while the proliferative diabetic retinopathy (PDR) subgroup did not reveal significant differences in either SNP rs145204276 or rs55829688 distributions compared to the non-DR group. Furthermore, patients with a GAS5 SNP rs145204276 Del/Del showed a significantly shorter DM duration than the wild type (Ins/Ins) (p = 0.021). In conclusion, our findings demonstrate that the GAS5 SNP rs145204276 Del/Del variant is associated with an increased susceptibility to DR in DM patients, particularly in those patients with NPDR.

Systemic retinal biomarkers

PURPOSE OF REVIEW

Systemic retinal biomarkers are biomarkers identified in the retina and related to evaluation and management of systemic disease. This review summarizes the background, categories and key findings from this body of research as well as potential applications to clinical care.

RECENT FINDINGS

Potential systemic retinal biomarkers for cardiovascular disease, kidney disease and neurodegenerative disease were identified using regression analysis as well as more sophisticated image processing techniques. Deep learning techniques were used in a number of studies predicting diseases including anaemia and chronic kidney disease. A virtual coronary artery calcium score performed well against other competing traditional models of event prediction.

SUMMARY

Systemic retinal biomarker research has progressed rapidly using regression studies with clearly identified biomarkers such as retinal microvascular patterns, as well as using deep learning models. Future systemic retinal biomarker research may be able to boost performance using larger data sets, the addition of meta-data and higher resolution image inputs.

Retinal Neurovascular Impairment in Non-diabetic and Non-dialytic Chronic Kidney Disease Patients

Background: Widespread neural and microvascular injuries are common in chronic kidney disease (CKD), increasing risks of neurovascular complications and mortality. Early detection of such changes helps assess the risks of neurovascular complications for CKD patients. As an extension of central nervous system, the retina provides a characteristic window to observe neurovascular alterations in CKD. This study aimed to determine the presence of retinal neurovascular impairment in different stages of CKD. Methods: One hundred fifteen non-diabetic and non-dialytic CKD patients of all stages and a control group of 35 healthy subjects were included. Retinal neural and microvascular parameters were obtained by optical coherence tomography angiography (OCTA) examination. Results: CKD 1-2 group (versus control group) had greater odds of having decreased retinal ganglion cell-inner plexiform layer thickness (GC-IPLt) (odds ratio [OR]: 0.92; 95% confidence interval [CI]: 0.86-0.98), increased ganglion cell complex-focal loss volume (GCC-FLV) (OR: 3.51; 95% CI: 1.27-9.67), and GCC-global loss volume (GCC-GLV) (OR: 2.48; 95% CI: 1.27-4.82). The presence of advanced stages of CKD (CKD 3-5 group versus CKD 1-2 group) had greater odds of having decreased retinal vessel density in superficial vascular plexus (SVP)-WholeImage (OR: 0.77, 95% CI: 0.63-0.92), SVP-ParaFovea (OR: 0.83, 95% CI: 0.71-0.97), SVP-ParaFovea (OR: 0.76, 95% CI: 0.63-0.91), deep vascular plexus (DVP)-WholeImage (OR: 0.89, 95% CI: 0.81-0.98), DVP-ParaFovea (OR: 0.88, 95% CI: 0.78-0.99), and DVP-PeriFovea (OR: 0.90, 95% CI: 0.83-0.98). Besides, stepwise multivariate linear regression among CKD patients showed that β2-microglobulin was negatively associated with GC-IPLt (β: -0.294; 95% CI: -0.469 ∼ -0.118), and parathyroid hormone was positively associated with increased GCC-FLV (β: 0.004; 95% CI: 0.002∼0.006) and GCC-GLV (β: 0.007; 95% CI: 0.004∼0.01). Urine protein to creatinine ratio was positively associated with increased GCC-FLV (β: 0.003; 95% CI: 0.001∼0.004) and GCC-GLV (β: 0.003; 95% CI: 0.001∼0.006). Conclusion: Retinal neuronal impairment is present in early stages of CKD (stages 1-2), and it is associated with accumulation of uremic toxins and higher UACR, while retinal microvascular hypoperfusion, which is associated with worse eGFR, was only observed in relatively advanced stages of CKD (stages 3-5). The results highlight the importance of monitoring retinal neurovascular impairment in different stages of CKD.

Impact of blood pressure control on retinal microvasculature in patients with chronic kidney disease

Chronic kidney disease (CKD) is an emerging disease worldwide. We investigated the relationship between blood pressure (BP) control and parafoveal retinal microvascular changes in patients with CKD. This case–control study enrolled 256 patients with CKD (stage 3–5) and 70 age‐matched healthy controls. Optical coherence tomography angiography showed lower superficial vascular plexus (SVP) vessel density, lower deep vascular plexus (DVP) vessel density, and larger SVP flow void area in the CKD group. The BP parameters at enrollment and during the year before enrollment were collected in patients with CKD. Partial correlation was used to determine the relationship between BP parameters and microvascular parameters after controlling for age, sex, diabetes mellitus, axial length, and intraocular pressure. The maximum systolic blood pressure (SBP) (p = 0.003) and within-patient standard deviation (SD) of SBP (p = 0.006) in 1 year were negatively correlated with SVP vessel density. The average SBP (p = 0.040), maximum SBP (p = 0.001), within-patient SD of SBP (p < 0.001) and proportion of high BP measurement (p = 0.011) in 1 year were positively correlated with the SVP flow void area. We concluded that long-term SBP was correlated with SVP microvascular injury in patients with CKD. Superficial retinal microvascular changes may be a potential biomarker for prior long-term BP control in these patients.