The HD-OCT Study May Be Useful in Searching for Markers of Preclinical Stage of Diabetic Retinopathy in Patients with Type 1 Diabetes

Correlations between Retinal Microvascular Parameters and Clinical Parameters in Young Patients with Type 1 Diabetes Mellitus: An Optical Coherence Tomography Angiography Study

OBJECTIVES

In the current study, we investigated the correlations between retinal microvascular parameters using optical coherence tomography angiography (OCTA) and clinical parameters for a group of 69 young patients with type 1 diabetes mellitus (T1DM).

MATERIALS AND METHODS

This retrospective, exploratory study enrolled 69 patients between 5 years old and 30 years old who met the inclusion criteria. All the study participants underwent a comprehensive ophthalmic examination and OCTA scans for the evaluation of the retinal microcirculation. The retinal OCTA parameters were correlated with the following clinical parameters: the patient's age at the onset of the disease, the duration of T1DM, the BMI at the time of enrollment in the study, the HbA1C values at onset, the mean values of HbA1C over the period of monitoring the disease and the degree of DKA at onset.

RESULTS

For the study group, the foveal avascular zone (FAZ) area and perimeter correlated positively with the mean value of HbA1C (Pearson correlation, Sig.2-Tailed Area: 0.044; perimeter: 0.049). The total vessel density in the superficial capillary plexus (SCP) correlated negatively with the duration of T1DM, based on the superior and inferior analyzed areas (Spearman correlation, Sig.2-Tailed SCP in total region: 0.002; SCP in the superior region: 0.024; SCP in the inferior region: 0.050). The foveal thickness also correlated negatively with the levels of diabetic ketoacidosis (DKA) at onset (Spearman correlation, Sig.2-Tailed: 0.034) and the levels of HbA1C at onset (Spearman correlation, Sig.2-Tailed: 0.047). Further on, the study patients were distributed into two groups according to the duration of the disease: group 1 included 32 patients with a duration of T1DM of less than 5 years, and group 2 included 37 patients with a duration of T1DM of more than 5 years. Independent t-tests were used to compare the OCTA retinal parameters for the two subgroups. While the FAZ-related parameters did not show significant statistical differences between the two groups, the vessel densities in both the SCP and DCP were significantly lower in group 2.

CONCLUSIONS

Our data suggest that specific alterations in OCTA imaging biomarkers correlate with various clinical parameters: the FAZ area and perimeter increase with higher mean values of HbA1C, leading to poor metabolic control. Moreover, the SCP total vessel density decreases as the duration of T1DM increases. Regarding the vessel densities in the SCP and the DCP, they decrease with a duration of the disease of more than 5 years.

Choroidal thickness and choroidal vascularity index changes in children with type 1 diabetes mellitus without retinopathy

BACKGROUND

Diabetic retinopathy is one of the most important causes of low vision in the working age group. Retinopathy findings start earlier and have a worse prognosis in type 1 DM. The aim of the this study was to compare the choroidal thickness (CT) and choroidal vascular index (CVI) values of type 1 diabetes mellitus (DM) patients without retinopathy findings in pediatric patients and healthy children.

METHODS

The study included 89 children, including 43 type 1 DM patients and 46 healthy controls. The age, gender, duration of DM, hemoglobin A1c (HbA1c), refractive error, intraocular pressure (IOP) and axial length (AL) of the participants were noted. CT measurements were performed subfoveally, 1000 µm from the fovea in the nasal and temporal quadrants. The total choroidal area (TCA), luminal area (LA) and stromal area (SA) were calculated using the binarization method using the image J program. The CVI was determined by dividing the luminal area by the total choroidal area.

RESULTS

There were no significant differences between the participants in terms of age, gender, spherical equivalent, IOP, and AL. There was no significant difference between the groups in terms of CT. TCA, LA and SA values were significantly higher in the Type 1 DM group (p=0.034, p=0.036, p=0.037, respectively). There was no significant difference between the groups in terms of the CVI.

CONCLUSIONS

The TCA, LA, and SA values were significantly higher in the type 1 DM group. LA/SA and CVI values were lower in the type 1 DM group, although not significantly. There was a negative correlation between the duration of DM and LA/SA as well as CVI. This suggests that vascular reduction starts in the early stages.

Long-term complications of type 1 diabetes: what do we know and what do we need to understand?

Long-term complications of type 1 diabetes (T1D) include microvascular complications and macrovascular disease. Despite the important advances in the treatment of T1D of the last decades, these complications still represent the leading cause of morbidity and mortality in patients with T1D. Extensive evidence indicates that structural and functional alterations of the kidney, retina, nerves and large arteries occur already in the first years after the onset of diabetes. We performed a comprehensive review of the available evidence on screening, diagnosis, prevention and treatment of vascular complications of T1D. In particular, we focused on three major challenges related to long-term complications of T1D: 1) finding of new biomarkers and diagnostic methods able to identify early signs of complications; 2) identifying specific risk factors for the development of these complications; 3) identifying and implementing new therapeutic strategies able to prevent the development and progression of vascular complications.

Reduced minimum rim width of optic nerve head: a potential early marker of retinal neurodegeneration in children and adolescents with type 1 diabetes

AIMS

To determine whether early retinal neurodegenerative changes in pediatric patients with type 1 diabetes (T1D) can be detected by spectral domain-optical coherence tomography (SD-OCT) and whether such changes are associated with risk factors for T1D complications.

METHODS

A total of 147 T1D children/adolescents and 51 healthy controls underwent SD-OCT. Spherical refractive error (SRE), macular total retinal thickness (TRT), ganglion cell layer (GCL), retinal nerve fiber layer (RNFL), minimum rim width (MRW), and Bruch's membrane opening area (BMOA) were measured. Clinical and biochemical parameters were recorded at the time of SD-OCT and starting at T1D onset. Multiple regression models were calculated using SD-OCT parameters as dependent and risk factors as independent variables.

RESULTS

MRW was significantly thinner in the T1D patients (global MRW:361.58vs386.33 µm; p = 0.009), while RNFL and macular parameters were similar for both groups. MRW was inversely correlated with mean HbA1c (r ≥ -0.180, p < 0.05). Multiple regression showed that part of the variability in MRW was explained by HbA1c and BMOA (R² = 0.21; p < 0.001), independent of other cardiometabolic risk factors.

CONCLUSIONS

MRW reduction could be a potential early marker of retinal neurodegeneration detectable in pediatric patients with T1D. The association between MRW and mean HbA1c suggests that glucometabolic control may affect early retinal neurodegeneration starting in childhood.

Inflammatory cells proliferate in the choroid and retina without choroidal thickness change in early Type 1 diabetes

Increasing evidence points to inflammation as a key factor in the pathogenesis of diabetic retinopathy (DR). Choroidal inflammatory changes in diabetes have been reported and in vivo choroidal thickness (CT) has been searched as a marker of retinopathy with contradictory results. We aimed to investigate the early stages in the retina and choroid in an animal model of Type 1 diabetes. Type 1 diabetes was induced in male Wistar rats via a single i.p. streptozotocin injection. At 8 weeks after disease onset, CT, choroidal vascular density, VEGF and VEGFR2 expression, microglial cell and pericyte distribution were evaluated. Diabetic rats showed no significant change in CT and choroidal vascular density. A widened pericyte-free gap between the retinal pigment epithelium and the choroid was observed in diabetic rats. The immunoreactivity of VEGFR2 was decreased in the retina of diabetic rats, despite no statistically significant difference in the immunoreactivity of VEGF. The density of microglial cells significantly increased in the choroid and retina of diabetic rats. Reactive microglial cells were found to be more abundant in the choroid of diabetic rats. Evidences of the interconnection between the superficial, intermediate, and deep plexuses of the retina were also observed. At early stages, Type 1 diabetes does not affect choroidal thickness and choroidal vascular density. Proliferation and reactivity of microglial cells occurs in the choroidal stroma and the retina. The expression of VEGFR2 decreases in the retina.

Strong Correlation of Renal Function with Choroidal Thickness in Patients with Type 2 Diabetes: Retrospective Cross-Sectional Study

The purpose of this study was to analyze the correlation between renal function and subfoveal choroidal thickness (SFChT) in treatment-naïve proliferative diabetic retinopathy (PDR) patients. This study included 85 eyes of 52 treatment-naïve PDR patients who underwent kidney function testing and urinalysis and 42 eyes of 33 age-matched controls. Treatment-naïve eyes with PDR were categorized into pachychoroid and leptochoroid groups based on the SFChT of the control group. Kidney function profiles were compared between pachychoroid and leptochoroid groups; the relationship between kidney function profile and SFChT was evaluated using regression analysis. Compared with the pachychoroid group, the leptochoroid group had significantly higher serum creatinine (p = 0.026), cystatin C (p = 0.004), and phosphorus (p < 0.001) levels and a lower estimated glomerular filtration rate (eGFR) (p < 0.001). Multivariate linear regression analyses showed that SFChT was positively correlated with eGFR (Cystatin C) (p = 0.007) and negatively correlated with serum phosphorus (p = 0.001). SFChT of patients with eGFR < 30 mL/min/1.73 m² and serum phosphorus level ≥4.0 mg/dL was less than that of patients with higher eGFR and lower serum phosphorus level. The choroidal thickness of treatment-naïve PDR patients is closely affected by renal function. Kidney function test should be considered if SFChT of patients with treatment-naïve PDR is reduced.

Evaluation of Foveal and Parafoveal Microvascular Changes Using Optical Coherence Tomography Angiography in Type 2 Diabetes Patients without Clinical Diabetic Retinopathy in South Korea

The aim of this study was to investigate foveal and parafoveal microvascular changes in retinal vascular plexuses in patients with type 2 diabetes mellitus (DM) without clinical diabetic retinopathy (NDR) using optical coherence tomography angiography (OCTA) in South Korea. We included 64 patients in the NDR group and included 48 healthy control subjects for comparison. All subjects underwent ocular examination with visual acuity and wide-field fundus photos. Foveal and parafoveal vessel density and foveal avascular zone (FAZ) area (mm²) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were analyzed. Foveal vessel densities in both the SCP and DCP were decreased in the NDR group compared to the controls (p = 0.034 and 0.001, respectively). Vessel densities in the superior and inferior parafoveae in the DCP were decreased in the NDR group compared to the controls (p = 0.006 and 0.034, respectively). The FAZs of the SCP and DCP were significantly different between the NDR group and the controls (p = 0.003 and 0.001, respectively). The average vessel densities of the SCP and DCP were not correlated with HbA1c, serum creatinine, or the duration of DM in the NDR group. We demonstrated that OCTA can identify early-stage DR before the manifestation of clinically apparent retinopathy in diabetic eyes. Diabetic patients without clinical DR have microvascular alterations (foveal vessel density, parts of the parafovea, and enlarged FAZ) in the SCP and DCP. Our results suggest that OCTA might be a promising tool for early detection of eyes with DR.

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