EARLY RETINAL MICROVASCULAR ABNORMALITIES IN YOUNG ADULTS WITH TYPE 1 DIABETES MELLITUS WITHOUT CLINICALLY EVIDENT DIABETIC RETINOPATHY

Quantitative Analysis of the Vasculature and Cone Photoreceptors in Subjects With Diabetes Without Diabetic Retinopathy

PURPOSE

To characterize any differences in the vasculature and cone photoreceptor packing geometry (CPG) between subjects with diabetes without/no diabetic retinopathy (NDR) and healthy controls.

METHODS

Eight NDR and five controls were enrolled. Optical coherence tomography angiography (OCTA) taken at the macula was used to measure vessel density, vessel length density, and vessel density index (VDI) in three vascular plexuses, namely, the superficial vascular plexus, intermediate capillary plexus, and deep capillary plexus (DCP). The choriocapillaris (CC) flow deficit (FD) was also measured. OCTA images were binarized and processed to extrapolate the parafovea and parafoveal quadrants and the OCTA indices mentioned above. The CC was processed with six different radii to quantify FD. Adaptive optics - scanning laser ophthalmoscopy images were acquired and processed to extract CPG indices, i.e., cone density (CD), cone-to-cone spacing (CS), linear dispersion index, heterogeneity packing index and percent of cells with six neighbors at 3.6° in the temporal retina.

RESULTS

In all eyes, statistically significant differences were found (i) in parafoveal FD across the six radii (p < 0.001) and (ii) in the correlation between the parafoveal temporal quadrant (PTQ) DCP VDI and CS (r = 0.606, p = 0.048). No other significant correlations were found. For OCTA or CPG indices, no significant differences were found between the cohorts in the parafovea or parafoveal quadrants.

CONCLUSIONS

CS is the most sensitive CPG index for detecting alterations in the cone mosaic. The DCP and the cone photoreceptors are significantly correlated, indicating that alterations in the DCP can affect the cones. Future work elucidating the vascular alterations and neurodegeneration present in diabetic eyes should focus on the DCP and multiple CPG indices, not solely CD. Moreover, such alterations are highly localized, hence using larger regions e.g. parafovea versus smaller areas, such as the PTQ, will potentially mask significant correlations.

Structural and functional characterization of retinal impairment in T1DM patients without diabetic retinopathy: a 3-year longitudinal study

PURPOSE

To analyze the progression of structural and functional retinal impairment in type 1 diabetes mellitus (T1DM) patients with no clinical signs of diabetic retinopathy (DR) during a 3-year follow-up.

METHODS

This was an observational longitudinal study. Post-pediatric T1DM patients without clinical signs of DR, and sex- and age-matched healthy subjects were recruited at San Raffaele Hospital (Milan, Italy). Each patient underwent a comprehensive ophthalmological evaluation, including optical coherence tomography (OCT), OCT-angiography (OCT-A), retinal static and dynamic vessel analysis (DVA), and microperimetry.

RESULTS

21 eyes of 21 T1DM patients (10 females; 24 ± 2 years old), and 21 age and sex-matched healthy subjects were enrolled. At baseline, T1DM eyes revealed a significantly decreased vessel length density using OCT-A (p < 0.001 and p = 0.046 in 3 × 3 and 6 × 6 mm images) and a significantly increased vessel density index (p = 0.013 and p = 0.087 in 3 × 3 and 6 × 6 mm images) of deep capillary plexus. DVA detected a significantly decreased vessel response to flicker light (p = 0.002). A significantly increased thickness of ganglion cellular layer 6-mm-diameter subfields in inferior and superior quadrants was found in diabetic patients (p < 0.001 in both subfields). At 3-years-follow-up no significant longitudinal changes were disclosed in all analyses.

CONCLUSIONS

Concomitant subclinical microvascular and neurodegenerative damages could be early signs of DR onset that precede functional alterations and clinical signs of DR development. These alterations demonstrated a stable trend over time.

Reduced macular thickness and vascular density in abnormal glucose metabolism patients: A meta-analysis of optical coherence tomography (OCT) and OCT angiography studies

BACKGROUND

Alterations in macular thickness and vascular density before clinically visible diabetic retinopathy (DR) remain inconclusive. This study aimed to determine whether retinal manifestations in abnormal glucose metabolism (AGM) patients differ from those in the healthy individuals.

METHODS

PubMed, Embase, and Web of Science were searched between 2000 and 2021. The eligibility criteria were AGM patients without DR. Primary and secondary outcomes measured by optical coherence tomography (OCT) and OCT angiography (OCTA) were analyzed and expressed as standardized mean differences (SMDs) with 95% confidence intervals (CIs). A random-effects model was used in the data synthesis. The potential publication bias for the variables was evaluated using Egger's test.

RESULTS

A total of 86 observational studies involving 13,773 participants and 15,416 eyes were included. OCT revealed that compared to healthy controls, the total macular thickness of AGM patients was thinner, including the thickness of fovea (-0.24, 95% CI [-0.39, -0.08]; P  = 0.002, I2  = 87.7%), all regions of parafovea (-0.32, 95% CI [-0.54, -0.11]; P  = 0.003; I2  = 71.7%) and the four quadrants of perifovea; the thickness of peripapillary retinal nerve fiber layer (pRNFL), macular retinal nerve fiber layer (mRNFL), and ganglion cell layer (GCL) also decreased. OCTA indicated that the superficial and deep vascular density decreased, the foveal avascular zone (FAZ) area enlarged, and the acircularity index (AI) reduced in AGM individuals.

CONCLUSIONS

Retinal thinning and microvascular lesions have occurred before the advent of clinically detectable DR; OCT and OCTA may have the potential to detect these preclinical changes.

REGISTRATION

PROSPERO; http://www.crd.york.ac.uk/prospero/ ; No. CRD42021269885.

Optical coherence tomography angiography for detection of microvascular changes in early diabetes: A systematic review and meta-analysis

AIMS

To evaluate the effectiveness of optical coherence tomography angiography (OCTA) in detecting early intraocular microvascular changes in diabetic patients.

MATERIALS AND METHODS

A systematic study search was performed on PubMed, Medline, Embase, and the Cochrane Library, ranging from January 2012 to March 2023. Controlled studies compared diabetes mellitus (DM) patients with non-diabetic retinopathy (NDR) or patients with mild non-proliferative diabetic retinopathy (mild NPDR) to healthy people. These studies included parameters of OCTA such as foveal avascular zone (FAZ), vessel density of superficial capillary plexus (VDscp), vessel density of deep capillary plexus (VDdcp), and peripapillary VD. The relevant effect model was used according to the heterogeneity, and the mean difference and 95% confidence intervals were calculated.

RESULTS

A total of 18 studies with 2101 eyes were eventually included in this meta-analysis. Our results demonstrated that early alterations of VDscp, VDdcp, and peripapillary VD in NDR patients had a significant difference compared with healthy people by OCTA (VDscp: WMD = -1.34, 95% CI: -1.99 to -0.68, P < 0.0001. VDdcp: WMD = -2.00, 95% CI: -2.95 to -1.04, P < 0.0001. Peripapillary VD: WMD = -1.07, 95% CI: -1.70 to -0.43, P = 0.0010). However, there was no statistically significant difference in total FAZ between them (WMD = -0.00, 95% CI: -0.02-0.01, P = 0.84). In addition, for patients with mild NPDR, OCTA could illustrate prominent changes in VDscp, VDdcp, and total FAZ compared with healthy people (VDscp: WMD = -6.11, 95% CI: -9.90 to -2.32, P = 0.002. VDdcp: WMD = -4.26, 95% CI: -5.95 to -2.57, P < 0.00001. FAZ: WMD = 0.06, 95% CI: 0.01-0.11, P = 0.03).

CONCLUSIONS

In diabetic patients with or without retinopathy, the parameters of OCTA such as VDscp, VDdcp, and peripapillary vessel density were demonstrated as potential biomarkers in monitoring the early alterations of retinal microangiopathy, while total FAZ may have no significant changes in diabetic patients without retinopathy.

Association of retinal microvascular density and complexity with incident coronary heart disease

BACKGROUND AND AIMS

The high mortality rate and huge disease burden of coronary heart disease (CHD) highlight the importance of its early detection and timely intervention. Given the non-invasive nature of fundus photography and recent development in the quantification of retinal microvascular parameters with deep learning techniques, our study aims to investigate the association between incident CHD and retinal microvascular parameters.

METHODS

UK Biobanks participants with gradable fundus images and without a history of diagnosed CHD at recruitment were included for analysis. A fully automated artificial intelligence system was used to extract quantitative measurements that represent the density and complexity of the retinal microvasculature, including fractal dimension (Df), number of vascular segments (NS), vascular skeleton density (VSD) and vascular area density (VAD).

RESULTS

A total of 57,947 participants (mean age 55.6 ± 8.1 years; 56% female) without a history of diagnosed CHD were included. During a median follow-up of 11.0 (interquartile range, 10.88 to 11.19) years, 3211 incident CHD events occurred. In multivariable Cox proportional hazards models, we found decreasing Df (adjusted HR = 0.80, 95% CI, 0.65-0.98, p = 0.033), lower NS of arteries (adjusted HR = 0.69, 95% CI, 0.54-0.88, p = 0.002) and venules (adjusted HR = 0.77, 95% CI, 0.61-0.97, p = 0.024), and reduced arterial VSD (adjusted HR = 0.72, 95% CI, 0.57-0.91, p = 0.007) and venous VSD (adjusted HR = 0.78, 95% CI, 0.62-0.98, p = 0.034) were related to an increased risk of incident CHD.

CONCLUSIONS

Our study revealed a significant association between retinal microvascular parameters and incident CHD. As the lower complexity and density of the retinal vascular network may indicate an increased risk of incident CHD, this may empower its prediction with the quantitative measurements of retinal structure.

Early retinal neurovascular findings in post-transplant diabetes mellitus patients without clinical signs of diabetic retinopathy

BACKGROUND

Post-transplant diabetes mellitus (PTDM) is a specific subtype of diabetes with an uncertain impact on mortality and morbidity in post-transplant patients. Diabetic retinopathy is the most common microvascular complication of diabetes mellitus, but the long-term clinical progression in PTDM is unknown. New technologies are being used to assess pre-clinical signs of retinal changes, such as swept-source optical coherence tomography (OCT) and OCT-angiography. The aim of this study was to detect pre-clinical structural and vascular changes in the retina using swept-source-OCT and OCT-angiography in patients with PTDM.

METHODS

In this retrospective cohort study, post-kidney transplant patients were divided into PTDM and non-PTDM (control) groups. Both eyes of eligible PTDM patients and controls were included in this study. Inner retinal layer thickness was measured with swept-source-OCT. Retinal capillary density and the foveal avascular zone were measured with OCT-angiography.

RESULTS

In the PTDM group, reduced thickness was found in the inferior ganglion cell layer plus inner plexiform layer (95% CI -8.76 to -0.68; p = 0.022) and the temporal inferior segment (95% CI -10.23 to -0.76; p = 0.024) of the inner retina, as well as in the retinal nerve fiber layer in the temporal (95% CI -34.78 to -9.28 p = 0.001) and temporal inferior segments (95% CI -33.26 to -5.03 p = 0.008). No significant differences were found in the vascular capillary plexus between groups at all depths, segments, or foveal avascular zone (p = 0.088).

CONCLUSIONS

According to OCT-angiography, PTDM patients had reduced inner neurosensory retinal layers but no significant change in vascular density, which suggests that early neuroretinal degeneration might occur prior to vascular changes secondary to PTDM. Prospective studies could help elucidate the clinical course of retinal neuropathy and microvascular pathology in PTDM and provide a better understanding of PTDM complications.

Right versus left eye asymmetry of microvasculature in diabetes revealed by optical coherence tomography angiography

In this study, we explored inter-ocular asymmetry (between the two eyes of the same patient) using optical coherence tomography angiography (OCTA) in patients with diabetes mellitus (DM) at different retinopathy stages. A total of 258 patients were divided into four groups: no DM, DM without diabetic retinopathy (DR), non-proliferative DR (NPDR), and proliferative DR (PDR). Superficial and deep vessel density (SVD, DVD), superficial and deep perfusion density (SPD, DPD), foveal avascular zone (FAZ) area, perimeter and circularity were calculated, and asymmetry index (AI) was used to evaluate the asymmetry of two eyes of the same subject. AIs of SPD, SVD, FAZ area and FAZ perimeter in the PDR group were larger than all other 3 groups (all p < 0.05). The AIs of DPD, DVD, FAZ area and FAZ perimeter in males were larger than in females (p = 0.015, p = 0.023, p = 0.006 and p = 0.017). Hemoglobin A1c (HbA1c) was positively correlated with AI of FAZ perimeter (p = 0.02) and circularity (p = 0.022). In conclusion, PDR patients' eyes were significantly asymmetric in both vascular density and FAZ metrics. Male sex and HbA1c are risk factors that influenced symmetry. This study highlights that right-left asymmetry should be taken into account in DR-related studies, particularly those analyzing microvascular changes with OCTA.

Correlation Between Coronary and Retinal Microangiopathy in Patients With STEMI

Purpose

To investigate the morphological and functional correlation between microvascular retinal changes in optical coherence tomography angiography (OCTA) and the microvascular coronary circulation in patients with ST elevation myocardial infarction (STEMI) coronary heart disease (CHD).

Methods

A total of 330 eyes from 165 participants (88 cases and 77 controls) were enrolled and imaged. Superficial capillary plexus (SCP) and deep capillary plexus (DCP) vascular density was measured in the central (1 mm) and perifoveal (1-3 mm) areas and in the superficial foveal avascular zone (FAZ) and choriocapillaris (3 mm). These parameters were then correlated to the left ventricular ejection fraction (LVEF), and the number of affected coronary arteries.

Results

Decreased vessel densities in the SCP and DCP and choriocapillaris were positively correlated to the LVEF values (P = 0.006, P = 0.026, and P = 0.002, respectively). No statistically significant correlation between the SCP and DCP central area or FAZ area was found. Regarding the number of affected vessels, significant negative correlations were revealed for the SCP and DCP central vessel densities (P < 0.001 and P < 0.001, respectively) and the SCP perifoveal vascular density (P = 0.009).

Conclusions

OCTA vascular indices are significantly correlated with morphological and functional parameters in patients with STEMI CHD. SCP vascular density especially seems to be a promising biomarker for the extent of both macrovascular damage (number of affected coronary arteries) and microvascular damage, as mirrored in the decreased LVEF at admission.

Translational Relevance

OCTA vascular indices offer a valuable insight into the microvascular status of coronary circulation.

Early Retinal Microvascular Changes Assessed with Swept-Source OCT Angiography in Type 1 Diabetes Patients without Retinopathy

Type 1 diabetes is a chronic disease that can lead to vision loss when diabetic retinopathy develops. Retinal microvascular alterations occur before the appearance of clinical signs on a fundus examination. This study aimed to analyze retinal vascular parameters on optical coherence tomography angiography (OCT-A) in patients with type 1 diabetes without diabetic retinopathy in comparison with non-diabetic volunteers. This cross-sectional study was conducted at Dijon University Hospital from 2018 to 2020. Vascular densities were measured using macular OCT-A. In total, 98 diabetes patients and 71 non-diabetic volunteers were enrolled. A statistically significant lower vascular density of the inner circle was found in the superficial capillary plexus (SCP) in the diabetes group (p < 0.01). There was a statistically significant correlation between central vascular density in the deep capillary plexus (DCP) and total daily insulin intake (p = 0.042); furthermore, use of the FreeStyle Libre (FSL) device was associated with higher vascular densities in both the SCP (p = 0.034 for outer circle density) and DCP (p < 0.01 for inner circle density and p = 0.023 for outer circle density). Retinal microvascularization was early-altered in type 1 diabetes, and using the FSL device seemed to preserve retinal microvascularization.

Retinal Neurodegeneration in Euglycemic Hyperinsulinemia, Prediabetes, and Diabetes

Diabetic retinopathy (DR) is a challenging public health problem mainly because of its growing prevalence and risk of blindness. In general, our current knowledge and practice have failed to prevent the onset or progression of DR to sight-threatening complications. While there are treatment options for sight-threatening complications of DR, it is crucial to pay more attention to the early stages of DR to decrease its prevalence. Growing evidence suggests many pathologic changes occur before clinical presentations of DR in euglycemic hyperinsulinemia, prediabetes, and diabetes. These pathological changes occur in retinal neurons, glia, and microvasculature. A new focus on these preclinical pathologies - especially on hyperinsulinemia - may provide further insight into disease mechanisms, endpoints for clinical trials, and druggable targets in early disease. Here, we review the current evidence on the pathophysiological changes reported in preclinical DR and appraise preventive and treatment options for DR.

Evaluation of early retinal vascular changes by optical coherence tomography angiography in children with type 1 diabetes mellitus without diabetic retinopathy

PURPOSE

To evaluate macular and peripapillary vascular changes by optical coherence tomography angiography (OCTA) in children with type 1 diabetes mellitus (T1DM) without diabetic retinopathy (DR).

METHODS

This study included 46 patients with T1DM and 46 age-sex matched healthy subjects. All participants were evaluated in terms of macular and optic disk parameters by using AngioVue. Foveal avascular zone (FAZ) area, macular and optic disk vessel density (VD) were analyzed. The correlation of these parameters with metabolic factors such as disease duration, mean hemoglobin A1c (HbA1c), insulin-like growth factor 1 (IGF-1) standard deviation score (SDS), homocysteine (Hcy) level, body mass index (BMI) SDS and daily insulin dose was also investigated in T1DM group.

RESULTS

No significant difference was found in FAZ area and optic disk radial peripapillary capillary (RPC) VD comparing diabetic and control groups. In all macular regions, VD was significantly lower in T1DM versus control group both in superficial capillary plexus (SCP) and deep capillary plexus (DCP). None of the metabolic parameters was correlated with FAZ area and optic disk RPC-VD. Vascular density in SCP was negatively correlated with mean HbA1c and positively correlated with IGF-1 SDS. Homocysteine level was negatively correlated with DCP-VD in all areas.

CONCLUSION

In children with T1DM without clinically apparent DR, VD in SCP and DCP was decreased and OCTA is a valuable imaging technique for detecting early vascular changes. The metabolic parameters such as mean HbA1c, IGF-1 SDS and Hcy affect the macular VD in diabetic children.

TRIAL REGISTRATION NUMBER

2011-KAEK-2, 2021/4, Trial registration date: 02.04.2021.

Evaluation of macular microvasculature and foveal avascular zone in patients with retinal vein occlusion using optical coherence tomography angiography

PURPOSES

To quantitatively evaluate the vessel density of macular microvasculature, choriocapillary, and foveal avascular zone (FAZ) in both eyes of patients with unilateral retinal vein occlusion (RVO) using the optical coherence tomography angiography (OCTA) compared with the normal controls.

METHODS

A retrospective review was conducted on 72 patients with unilateral RVO (72 eyes with RVO and 72 RVO fellow eyes) and 72 healthy individuals (72 normal control eyes). The 3 × 3 mm macular angiogram was acquired using the OCTA. The vessel densities of the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillary plexus (CCP) were measured, and FAZ was quantified.

RESULTS

The RVO eyes compared to their fellow eyes, and the fellow eyes compared to the normal controls, showed a significantly lower vessel density in both the SCP and DCP in the whole image and parafovea (P < 0.05) and the CCP (P < 0.05), except for the foveal region (P > 0.05). No significant differences between the RVO eyes and the fellow eyes in the FAZ area and perimeter (P > 0.05) were observed, while the acircularity index in the RVO eyes was significantly higher than the fellow eyes (P < 0.05). Additionally, the FD-300 in the RVO eyes was significantly lower than their fellow eyes (P < 0.05).

CONCLUSIONS

The OCTA reveals that the macular microvasculature of the RVO fellow eyes can be impaired in both the superficial and deep retinal layer as well as the choriocapillary, suggesting the influence of systemic factors in the development of RVO.