Quantitative analysis of retinal and choroidal microvascular parameters using optical coherence tomography angiography in children with nephrotic syndrome: a pilot study

Evaluation of retinal microcirculation by optical coherence tomography angiography in patients with primary membranous nephropathy

BACKGROUND

Primary membranous nephropathy (PMN) patients may experience retinal microvascular changes. However, current diagnostic methods for PMN are not accurate in analyzing these modifications. In the present study, optical coherence tomography angiography (OCTA) was used for quantitative measurement of microvascular changes in the eyes of PMN patients.

METHODS

A total of 26 patients with PMN and 26 healthy control (HC) were evaluated in this cross-sectional study. Optical coherence tomography (OCT) and OCTA were used to collect retinal thickness (RT) and microvascular parameters in the macula and optic disk in the superficial capillary plexus (SCP) of all subjects. Clinical data were collected from the PMN group. The OCT and OCTA data for PMN and HC group were compared, and the correlation between the OCTA and clinical data in the PMN group was determined.

RESULTS

Vascular density (VD) and perfusion density (PD) in the macular area of the PMN group were significantly lower than those of the HC group, especially in the temporal quadrant. No significant difference in the foveal avascular zone (FAZ), optic disc microvascular parameters, RT, and retinal nerve fiber layer (RNFL) thickness was observed between the two groups. Correlation was noted between VD and PD in the macular area and clinical indicators, such as serum creatinine, serum urea nitrogen, 24 h urine volume and urinary protein concentration.

CONCLUSION

Microvascular alterations in PMN patients occurred before ocular symptoms. The present quantitative study proposed a measurement method for detecting early retinal vascular injury in PMN patients.

Choroidal Vascularity Index and Choroidal Structural Changes in Children With Nephrotic Syndrome

Purpose

To investigate the choroidal vascularity index (CVI) and choroidal structural changes in children with nephrotic syndrome.

Methods

This was a cross-sectional study involving 45 children with primary nephrotic syndrome and 40 normal controls. All participants underwent enhanced depth imaging-optical coherence tomography examinations. An automatic segmentation method based on deep learning was used to segment the choroidal vessels and stroma, and the choroidal volume (CV), vascular volume (VV), and CVI within a 4.5 mm diameter circular area centered around the macular fovea were obtained. Clinical data, including blood lipids, serum proteins, renal function, and renal injury indicators, were collected from the patients.

Results

Compared with normal controls, children with nephrotic syndrome had a significant increase in CV (nephrotic syndrome: 4.132 ± 0.464 vs. normal controls: 3.873 ± 0.574; P = 0.024); no significant change in VV (nephrotic syndrome: 1.276 ± 0.173 vs. normal controls: 1.277 ± 0.165; P = 0.971); and a significant decrease in the CVI (nephrotic syndrome: 0.308 [range, 0.270-0.386] vs. normal controls: 0.330 [range, 0.288-0.387]; P < 0.001). In the correlation analysis, the CVI was positively correlated with serum total protein, serum albumin, serum prealbumin, ratio of serum albumin to globulin, and 24-hour urine volume and was negatively correlated with total cholesterol, low-density lipoprotein cholesterol, urinary protein concentration, and ratio of urinary transferrin to creatinine (all P < 0.05).

Conclusions

The CVI is significantly reduced in children with nephrotic syndrome, and the decrease in the CVI parallels the severity of kidney disease, indicating choroidal involvement in the process of nephrotic syndrome.

Translational Relevance

Our findings contribute to a deeper understanding of how nephrotic syndrome affects the choroid.

Evaluation of Visual Acuity, Macular Thickness, and Level of Proteinuria in Children with Nephrotic Syndrome

PURPOSE

Macular edema, serous retinal detachment, and retinal pigment epithelial detachment have been reported in patients with nephrotic syndrome. However, there is limited data about macular thickness in children with nephrotic syndrome. The aim of this study was to compare the mean macular thickness in children with nephrotic syndrome and in a control group and to correlate it with visual acuity and level of proteinuria.

METHODS

The comparative cross-sectional study included 66 children aged 6 to 17 years with nephrotic syndrome and healthy control seen in two tertiary centers in Malaysia. We recorded demographic data, as well as visual acuity, level of proteinuria, and the mean macular thicknesses in both groups. The mean macular thickness was measured using Stratus optical coherence tomography according to nine areas of the Early Treatment Diabetic Retinopathy Study map.

RESULTS

The mean foveal thickness was 238.15 ± 22.98 µm for children with nephrotic syndrome and 237.01 ± 22.60 µm for the control group. There was no significant difference in the mean macular thickness between the groups (p = 0.843). A significant correlation with visual acuity was observed in the superior outer macula (r = -0.41, p = 0.019), the nasal outer macula (r = -0.41, p = 0.019), and the inferior outer macula (r = -0.40, p = 0.021). There was no significant correlation between the mean macular thickness and level of proteinuria (p = 0.338), although those with higher levels of proteinuria demonstrated a trend towards increased macular thickness.

CONCLUSIONS

The mean macular thickness in children with nephrotic syndrome was similar to that of healthy children. A significant correlation between the mean thickness of the outer macular layer and the presenting visual acuity was observed. There was no correlation between the mean macular thickness and the level of proteinuria.

Quantitative vessel density analysis of macular and peripapillary areas by optical coherence tomography angiography in adults with primary nephrotic syndrome

PURPOSE

To compare the microvascular parameters of macular and peripapillary areas in adults with primary nephrotic syndrome (PNS) and healthy controls (HCs).

METHODS

In this cross-sectional study, optical coherence tomography angiography (OCTA) was used to evaluate the changes in retinal microvascular in 37 adult patients with PNS and 30 HCs in this study. All subjects underwent OCTA for measuring vascular density (VD), perfusion density (PD), and foveal avascular zone (FAZ) in the superficial capillary plexus (SCP) and optical coherence tomography (OCT) for measuring central macular thickness (CMT) and retinal nerve fiber layer (RNFL) thickness. The following clinical data of the PNS group were collected: hemoglobin, platelet, total protein, albumin, prealbumin, creatinine, urea nitrogen, glomerular filtration rate, blood lipid, urinary protein, urine microalbumin, urine microalbumin/creatinine, 24-h urine volume, and 24-h urine protein quantification. The OCTA data were compared between patients with PNS and HCs, and the correlation between the OCTA data and clinical data was analyzed in the PNS group.

RESULTS

VD and PD in the macular area of the PNS group were significantly lower than those in the HC group (VD: 17.025 ± 2.229 vs. 18.290 ± 0.721, P = 0.001; PD: 0.417 ± 0.058 vs. 0.450 ± 0.019, P = 0.003). No significant differences in the FAZ area and perioptic disc microvascular parameters were observed between the two groups, and patients in the PNS group showed consistent changes in the left and right eyes. VD and PD in the central macular area were positively correlated with plasma prealbumin level (VD: ρ = 0.541, P = 0.001; PD: ρ = 0.562, P < 0.001) and negatively correlated with urinary protein level (VD: ρ = -0.579, P < 0.001; PD: ρ = -0.596, P < 0.001).

CONCLUSIONS

In adult patients with PNS, the decrease in VD and PD was mainly occurred in the macular area. Partly vascular density of the macular area was positively correlated with plasma prealbumin level and negatively correlated with urinary protein level. OCTA provides a convenient, non-invasive and effective method for evaluating and monitoring retinal microcirculation damage in patients with PNS.

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 microvascular metrics in untreated essential hypertensives using optical coherence tomography angiography

PURPOSE

To quantify early changes of macular microvascular density, complexity, and peripapillary vessel caliber in hypertension using optical coherence tomography angiography (OCTA).

METHODS

Hypertension (137 eyes) and healthy eyes (79 eyes) as control were involved in this prospective observational study. Indices of the microcirculation included vessel density (VD), skeleton density (SD), vessel diameter index (VDI), fractal dimension (FD) and foveal avascular zone (FAZ) of superficial retinal layer (SRL) and deep retinal layer (DRL), and peripapillary vessel calibers. The correlation of these indices with mean arterial pressure (MAP) and ocular perfusion pressure (OPP) was analyzed.

RESULTS

Mean VD of DRL, SD of SRL and DRL, and FD of SRL and DRL were significantly reduced in the macula of hypertensive eyes (all P < 0.01). Meanwhile, hypertensive eyes had margin results of narrower peripapillary arteriolar caliber (P = 0.04). No significant finding was demonstrated on VD of SRL, VDI and FAZ of SRL and DRL, peripapillary total vascular caliber, and peripapillary venal caliber (all P > 0.05). SD and VD of the DRL correlated negatively with MAP (both R = - 0.152, P = 0.03).

CONCLUSION

OCTA algorithms may provide an additional inexpensive tool to aid in the preclinical assessment of hypertensive subject.