The Role of Diabetic Choroidopathy in the Pathogenesis and Progression of Diabetic Retinopathy.

Diabetic choroidopathy was first described on histopathological specimens of diabetic eyes. This alteration was characterized by the accumulation of PAS-positive material within the intracapillary stroma. Inflammation and polymorphonuclear neutrophils (PMNs) activation are crucial elements in choriocapillaris impairment. The evidence of diabetic choroidopathy in vivo was confirmed with multimodal imaging, which provides key quantitative and qualitative features to characterize the choroidal involvement. The choroid can be virtually affected in each vascular layer, from Haller's layer to the choriocapillaris. However, the damage on the outer retina and photoreceptor cells is essentially driven by a choriocapillaris deficiency, which can be assessed through optical coherence tomography angiography (OCTA). The identification of characteristic features of diabetic choroidopathy can be significant for understanding the potential pathogenic and prognostic implications in diabetic retinopathy.

Differential effects of high-intensity interval training (HIIT) on choriocapillaris perfusion in healthy adults and patients with type 1 diabetes mellitus (T1DM).

PURPOSE: To investigate the effects of a four-week high-intensity interval training (HIIT) on choriocapillaris (CC) perfusion in young healthy adults and type 1 diabetes mellitus (T1DM) patients. METHODS: Data of two HIIT studies with baseline to follow-up comparison were retrospectively analysed. Twenty healthy participants and twenty T1DM patients without clinical signs of diabetic retinopathy were included. All participants had performed a four-week all-out HIIT protocol with a total of 8 training sessions. Changes in physical fitness were assessed using power output at the individual aerobic lactate threshold (IANT). Optical coherence tomography angiography (OCTA) imaging was performed at baseline and follow-up. CC images were analysed for number, size and total area of flow deficits (FD), mean signal intensity, signal intensity standard deviation and kurtosis of signal intensity distribution. RESULTS: At baseline, CC OCTA revealed a lower and more heterogeneous intensity signal in T1DM eyes (mean intensity signal and standard deviation of signal intensity, p < 0.001). Percent of CC FD area was greater in T1DM eyes (p < 0.001). While T1DM patients showed greater improvement of exercise capacity at IANT than healthy controls (group×time p = 0.0403), CC FD area and standard deviation of intensity increased in healthy controls but not in T1DM patients (group×time p ≤ 0.029). Moreover, linear regression slopes of FD region distribution differed significantly at baseline and follow-up (p = 0.0002) in healthy individuals but not in T1DM patients. CONCLUSIONS: Effects of regular physical exercise performed as HIIT on CC perfusion were only seen in healthy participants, not in T1DM patients suggesting impaired CC adaptation in T1DM.

Topographic analysis of retinal and choroidal microvasculature according to diabetic retinopathy severity using optical coherence tomography angiography.

PURPOSE: To investigate the topographic changes in the retinal capillary plexus and the choriocapillaris according to the severity of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA). METHODS: Subjects were recruited and classified into one of the following four groups: normal controls (n = 52), diabetes without DR (n = 49), non-proliferative DR (n = 51) and proliferative DR (n = 38). Using OCTA, the superficial capillary plexus (SCP), deep capillary plexus (DCP) and the choriocapillaris vessel densities were measured and compared in different macular areas: the fovea (1-mm diameter circular area), parafovea (1-3-mm diameter ring) and perifovea (3-6-mm ring). RESULTS: With DR progression, vessel densities in the SCP and DCP as well as the choriocapillaris decreased, while the foveal avascular zone area increased (p < 0.001 for all). Compared with controls, the SCP and DCP vessel densities of the diabetes without DR group were decreased in all areas of the macula (p < 0.020 for all), while the choriocapillaris vessel density was decreased only in the perifoveal area (p = 0.823 for the foveal area; p = 0.631 for the parafoveal area; p = 0.039 for the perifoveal area). Multivariate linear regression analyses revealed that all retinal and choroidal microvascular indices were significantly associated with the DR severity. CONCLUSION: The morphological changes in the macular microvasculature were associated with DR severity. Also, the changes were found to be more vulnerable in the retinal capillary plexuses than the choriocapillaris.

Alpha-Smooth Muscle Actin-Positive Perivascular Cells in Diabetic Retina and Choroid.

Structural alterations of pericytes in microvessels are important features of diabetic retinopathy. Although capillary pericytes had been known not to have α-smooth muscle actin (αSMA), a recent study revealed that a specific fixation method enabled the visualization of αSMA along retinal capillaries. In this study, we applied snap-fixation in wild type and streptozotocin-induced diabetic mice to evaluate the differences in vascular smooth muscle cells of the retina and the choroid. Mice eyeballs were fixed in ice-cold methanol to prevent the depolymerization of filamentous actin. Snap-fixated retina showed αSMA expression in higher-order branches along the capillaries as well as the arterioles and venules, which were not detected by paraformaldehyde fixation. In contrast, most choriocapillaris, except those close to the arterioles, were not covered with αSMA-positive perivascular mural cells. Large choroidal vessels were covered with more αSMA-positive cells in the snap-fixated eyes. Diabetes induced less coverage of αSMA-positive perivascular mural cells overall, but they reached higher-order branches of the retinal capillaries, which was prominent in the aged mice. More αSMA-positive pericytes were observed in the choroid of diabetic mice, but the αSMA-positive expression reduced with aging. This study suggests the potential role of smooth muscle cells in the pathogenesis of age-related diabetic retinopathy and choroidopathy.

Optical coherence tomography angiography analysis of the choriocapillary layer in treatment-naïve diabetic eyes.

PURPOSE: To evaluate the capillary flow density (CFD) of choriocapillary (CC) microvasculature using optical coherence tomography angiography (OCT-A) in diabetic eyes and the association of CFD and systemic and metabolic factors. METHODS: Cross-sectional study. This study enrolled 282 eyes of 146 subjects, including 43 healthy control eyes, 56 diabetic eyes without diabetic retinopathy (DR), 43 eyes with mild nonproliferative DR (NPDR), 54 eyes with moderate NPDR, 38 eyes with severe NPDR, and 48 eyes with proliferative DR (PDR). CFD was measured in the CC layer. Clinical data were collected. Multiple linear regression analyses were performed to identify associated clinical variables. RESULTS: CFD in the CC layer presented a downward trend with DR progression. Comparisons of CFD in the CC layer between adjacent stages of DR revealed significant differences between severe NPDR and PDR using both 3-mm and 6-mm scan patterns (P = 0.003, P = 0.001). CFD in the CC layer in DR with diabetic macular edema (DME) was less than that in DR without DME using both 3-mm and 6-mm scan patterns (P < 0.001, P < 0.001). Coronary artery disease and atherosclerosis in other locations, estimated glomerular filtration rate, and increased HbA1c were associated with CFD in the CC layer using both 3-mm and 6-mm scan patterns (all P values < 0.05). CONCLUSIONS: OCT-A revealed decreased CFD in the CC layer in the PDR stage and the presence of DME. Diabetic patients with apparently decreased CFD should be assessed carefully under general conditions.

Optical Coherence Tomography Angiography in Healthy Subjects and Diabetic Patients.

Fluorescein angiography and indocyanine green angiography provide information about the normal retinal and choroidal vascular perfusion. They allow the evaluation of different diseases and increase the capability to define and diagnose several pathological conditions. Fluorescein angio graphy is the "gold standard" in imaging the retinal vascular bed and its changes, although not all the different layers of the capillary network can be visualized in a bidimensional examination. Optical coherence tomography angiography allows a depth-resolved visualization of the retinal and choroidal microvasculature, by calculating the difference (decorrelation) between static and nonstatic tissue. Given that the main moving elements in the eye fundus are contained in vessels, determining a vascular decorrelation signal permits a three-dimensional visualization of the retinal and choroidal vascular network without the administration of an intravenous dye. Moreover, a complete morphofunctional assessment may help in defining both the origin and the clinical activity of different vascular diseases such as diabetic retinopathy.

Alteration of layer thickness in the choroid of diabetic patients.

IMPORTANCE: Choroidal thickness changes in diabetic retinopathy improve understanding the pathophysiology and managements of this disease. BACKGROUND: To examine the choroidal layer thickness in diabetes mellitus (DM) patients and normal individuals, and to compare the findings based on medical history of systemic DM treatments, and stage of diabetic retinopathy (DR). DESIGN: Case control study. PARTICIPANTS: Two hundred sixty eight eyes of 134 DM patients and age-matched 72 healthy controls of 92 eyes. METHODS: Central choroidal layer thickness (total, inner, and outer layers) was measured using enhanced depth imaging OCT. DM patients were divided into two groups; the DM treated group (88 cases), and the untreated group (46 cases). These two groups were further classified into four groups; no DR (NDR), mild/moderate non-proliferative DR (mNPDR), severe NPDR and PDR. MAIN OUTCOME MEASURES: Comparison of subfoveal choroid layer thickness in control and diabetic patient groups. RESULTS: Choroidal thickness measurements of diabetic eyes had strong correlation between masked raters in choroidal layers, proving high reproducibility. The total and outer choroid thicknesses in mNPDR in the DM untreated group were significantly thinner than normal controls (each P<0.05). Choroidal outer layer thickness of the severe NPDR in the DM untreated group was significantly thicker than normal controls (P<0.05). In the DM treatment group, there were no significant differences from the control group regarding choroidal layer thicknesses and all stages of DR. CONCLUSIONS AND RELEVANCE: The choroidal thickness significantly changed in the DM untreated group, and the main anatomical changes might result from the outer layer.

Alteration of layer thickness in the choroid of diabetic patients.

IMPORTANCE: Choroidal thickness changes in diabetic retinopathy improve the understanding of the pathophysiology and managements of this disease. BACKGROUND: To examine the choroidal layer thickness in diabetes mellitus (DM) patients and normal individuals, and to compare the findings based on medical history of systemic DM treatments, and stage of diabetic retinopathy (DR). DESIGN: Case control study. PARTICIPANTS: Two hundred and sixty-eight eyes of 134 DM patients and age-matched 72 healthy controls of 92 eyes. METHODS: Central choroidal layer thickness (total, inner and outer layers) was measured using enhanced depth imaging OCT. DM patients were divided into two groups; the DM-treated group (88 cases), and the untreated group (46 cases). These two groups were further classified into four groups; no DR (NDR), mild/moderate non-proliferative DR (mNPDR), severe NPDR and PDR. MAIN OUTCOME MEASURES: Comparison of subfoveal choroid layer thickness in control and diabetic patient groups. RESULTS: Choroidal thickness measurements of diabetic eyes had strong correlation between masked raters in choroidal layers, proving high reproducibility. The total and outer choroid thicknesses in mNPDR in the DM-untreated group were significantly thinner than normal controls (each P < 0.05). Choroidal outer layer thickness of the severe NPDR in the DM-untreated group was significantly thicker than normal controls (P < 0.05). In the DM treatment group, there were no significant differences from the control group regarding choroidal layer thicknesses and all stages of DR. CONCLUSIONS AND RELEVANCE: The choroidal thickness significantly changed in the DM-untreated group, and the main anatomical changes might result from the outer layer.

Diabetic choroidopathy: a review of the current literature.

Diabetic retinopathy is an increasingly prevalent disease, and a leading contributor to the burden of all-cause blindness worldwide. In addition to retinal changes, choroidal abnormalities are common in patients with diabetes. The first studies concerning this vascular structure were based on histologic, indocyanine angiography and laser Doppler flowmetry techniques, but the development of new optical coherence tomography (OCT) technologies and imaging software for enhanced depth imaging (EDI)-OCT in recent years has made it possible to provide more detailed images of the choroidal anatomy and topography.In diabetic patients, several choroidal changes have been described in the literature throughout the years; the recent focus is choroidal thickness, which is significantly different from that in healthy patients. However, understanding choroidal manifestations of diabetic eye disease remains a real challenge, and this gap is hindering efforts towards better defining choroidal evaluation as a predictive factor for disease evolution and treatment response.This review aims to summarize the recent literature concerning changes in choroidal structure in diabetic patients, the relationship to diabetic retinal disease progression, and finally, the current and potential application of the measurement of variations in choroidal thickness for patient management.

Diabetic uveopathy.

Diabetes can involve several ocular structures -- including the cornea, lens, and retina -- and cause vascular and neural changes in these tissues. Although retinopathy is the most common ocular complication of diabetes, uveopathy can also be observed. This includes vascular, neural, muscular, and basement membrane changes. The main clinical manifestations of diabetic uveopathy are anterior uveitis and abnormal pupillary dynamics. Fluorescein angiography, optical coherence tomography, and optical coherence tomography angiography are ideal for the imaging of vascular changes of the iris and choroid, while dynamic pupillometry is a simple screening tool to detect neuropathy. Additionally, ultrasound biomicroscopy can provide clear images of the ciliary body. Iris abnormalities, primarily angiopathy and neuropathy, can appear as alterations in vascular diameter, neovascularization, and abnormal pupillary dynamics. Choroidal abnormalities primarily affect blood vessels, including alterations in vascular diameter, microaneurysm formation, and neovascularization. The abnormal manifestations in the ciliary body include a decrease in vessel count, alterations in their diameter, isolated angiomatous dilatation, and diffuse thickening of the basal membrane of the pigment epithelium.

Choroidal Changes in Patients with Diabetic Retinopathy: A Retrospective Study.

This study aimed to investigate the characteristic choroidal changes in patients with diabetic retinopathy and identify factors affecting choroidal thickness (CTh), choroidal vascular index (CVI), and choriocapillaris flow. We retrospectively analyzed 79 eyes of 48 patients with diabetes between August 2021 and February 2022. We collected laboratory data, including HbA1c, serum creatinine, blood urea nitrogen, triglyceride, total cholesterol, high-density lipoprotein, and low-density lipoprotein (LDL) levels. Optical coherence tomography images of the foveal avascular zone, retinal vascular density, choroidal flow, retinal thickness, CTh, and CVI were analyzed. Possible determining factors affecting CTh, CVI, and choriocapillaris flow were analyzed using nonparametric multivariate analysis. LDL (p < 0.001) positively correlated with CTh, whereas CVI (p = 0.007) was negatively correlated with CTh in diabetic patients with diabetes. We also identified a negative correlation between choriocapillaris flow and deep parafoveal retinal vessel density in patients with low-grade diabetic retinopathy (DR), which diminished in those with more advanced DR. Our study provides further information on the changes in choroidal structure and blood flow in patients with diabetes.

Evaluation of the effect of sodium-glucose cotransporter-2 inhibitor treatment on choroidal vascular parameters in patients with type 2 diabetes mellitus.

BACKGROUND: To evaluate the effect of sodium-glucose cotransporter-2 inhibitor treatment on choroidal vascular parameters in patients with type 2 diabetes mellitus (T2DM). METHODS: Twenty eyes of 20 patients with T2DM without diabetic retinopathy and 20 eyes of 20 age- and sex-matched patients as the control group were included in the study. The patients were evaluated using enhanced depth imaging optic coherence tomography before treatment and at the third month of treatment. The choroidal images were binarized into luminal areas (LAs) and stromal areas (SAs). The choroidal vascularity index (CVI) was defined as the ratio of the LA to the total circumscribed choroid area (TCA). RESULTS: The mean age of the patients was 56.65±8.41 years. The patients' mean disease duration was 6.65±5.72 years, the mean HbA1c level was 8.89±1.62%, and the mean body mass index was 33.13±4.84 kg/m2. The subfoveal TCA, subfoveal LA, subfoveal SA, total TCA, total LA, and total SA values ​​of the patient group were found to be significantly lower than those of the control group (p = 0.006, p = 0.003, p = 0.028, p = 0.001, p = 0.001, and p = 0.006, respectively). There was a significant increase in the subfoveal TCA, subfoveal LA, subfoveal SA, subfoveal CVI, total TCA, total LA, and total SA values ​​after empagliflozin treatment compared to before empagliflozin treatment (p = 0.005, p = 0.003, p = 0.021, p = 0.032, p < 0.001, p < 0.001, and p = 0.001 respectively). CONCLUSIONS: Empagliflozin provides an improvement in diabetic choroidal changes through its effect on choroidal vascularity parameters.

Alterations in the Choroidal Sublayers in Relationship to Severity and Progression of Diabetic Retinopathy: A Swept-Source OCT Study.

Purpose: To examine the association of baseline choroidal sublayers metrics with the risk of diabetic retinopathy (DR) progression over 2 years, with adjustment for confounding factors that affect choroidal measurements. Design: Prospective, observational cohort study. Participants: One hundred three eyes from 62 patients with diabetes mellitus (DM). Methods: Patients were followed up at 6-month intervals for at least 2 years. Choroidal metrics including choroidal area, choroidal thickness (CT), and choroidal vascularity index were measured for both (1) the choriocapillaris plus Sattler's layer and (2) the Haller's layer within the subfoveal and parafoveal region. Cox proportional models were constructed to estimate the relationship between baseline choroidal metrics and DR progression, adjusted for intereye correlation, established risk factors (i.e., duration of DM, glycated hemoglobin [HbA1c] level, body mass index [BMI], use of insulin, and mean arterial blood pressure [MABP]) and confounding factors of choroidal measurements (i.e., age and axial length). Additional predictive value of choroidal metrics was assessed using the C-statistic. Main Outcome Measures: Hazard ratios (HRs) calculated by Cox proportional hazards model to demonstrate the associations between baseline choroidal metrics and DR progression. Results: After adjusting for age, axial length, and intereye correlation, choroidal metrics in Haller's layer at baseline that were associated with a higher risk of DR progression included increases in subfoveal choroidal area (HR, 2.033; 95% confidence interval [CI], 1.179-3.505; P = 0.011), subfoveal plus parafoveal choroidal area (HR, 1.909; 95% CI, 1.096-3.326; P = 0.022), subfoveal CT (HR, 2.032; 95% CI, 1.181-3.498; P = 0.010), and subfoveal plus parafoveal CT (HR, 1.908; 95% CI, 1.097-3.319; P = 0.022). These associations remained statistically significant after additionally adjusting for duration of DM, HbA1c level, BMI, use of insulin, and MABP. Addition of these choroidal metrics significantly improved the discrimination for DR progression when compared with established risk factors alone (e.g., duration of DM and HbA1c; increase in C-statistic ranged from 8.08% to 9.67% [P < 0.05]). Conclusions: Eyes with a larger choroidal area and CT in Haller's layer at baseline were associated with a higher risk of DR progression over 2 years.

Clinical and angiographic characterization of choroidal neovascularization in diabetic retinopathy.

BACKGROUND: To report the clinical and angiographic characteristics of choroidal neovascularization in patients with diabetic retinopathy. METHODS: Patients of type 2 diabetes mellitus with presence of choroidal neovascularization in at least one eye were retrospectively analyzed. The study eyes were divided into three groups based on presence (active or scarred) or absence of choroidal neovascularization (fellow eyes). Imaging characteristics of active choroidal neovascularization were recorded using optical coherence tomography, fluorescein, and indocyanine angiography. Central macular thickness, subfoveal choroidal thickness, and large choroidal vessel layer thickness were compared at baseline and final visit. RESULTS: Our study reports the prevalence rate of choroidal neovascularization in eyes with diabetic retinopathy (0.27%; 36 out of 13,382 eyes). A total of 64 eyes of 32 patients (age, mean ± standard deviation: 68.5 ± 9.3 years) with baseline visual acuity of 0.69 ± 0.69 logarithm of minimum angle of resolution (Snellen equivalent 20/100) were included. Nonproliferative diabetic retinopathy (57 eyes) comprised the majority followed by proliferative diabetic retinopathy (7 eyes). Eyes with choroidal neovascularization (36, 56.25%) included both active (25) and scarred (11) choroidal neovascularization, with bilateral choroidal neovascularization in 4 patients. Type 1 choroidal neovascularization was the most common subtype of choroidal neovascularization on optical coherence tomography. Common etiologies for active choroidal neovascularization included age-related macular degeneration (3; 12%), myopia (1; 4%), and inflammatory choroidal neovascularization secondary to chorioretinitis (1; 4%). In the remaining 20 eyes, choroidal neovascularization formation was primarily due to diabetic choroidopathy. CONCLUSION: The prevalence of choroidal neovascularization in eyes with diabetic retinopathy is very low, with a lower prevalence of age-related macular degeneration. Diabetic choroidopathy plays a significant role in formation of choroidal neovascularization in eyes with diabetic retinopathy.

Functional correlation between choroidal and retinal vascularity in low-grade diabetic retinopathy.

AIMS: To perform an automated functional assessment of retinal and choroidal microvasculature in eyes with low-grade diabetic retinopathy (DR) using optical coherence tomography angiography (OCT-A) and to identify potential perfusion changes in case of early vascular damage. METHODS: This is an observational, case-control study of consecutive diabetic patients with level 20 DR severity scale score and age-matched healthy subjects. A prototypal OCT-angiography was used to obtain the OCT-angiograms of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC) layer. A validated automated microstructural analysis provided data on SCP, DCP and CC vascular perfusion density (VPD). A comparative assessment between different vascular layers and different groups was performed. RESULTS: Twenty-nine diabetic patients (7 females, 24%) and 20 healthy controls were enrolled. VPD values were significantly lower in the DCP (25.1% vs. 26.5%; p = 0.04) and CC (71.2% vs. 86.6%; p = 0.0001) of diabetic patients compared with controls. A statistically significant negative linear correlation was reported between CC VPD and DCP VPD in diabetic patients; at the reverse, a positive linear correlation between the same parameters was noticed in controls. CONCLUSION: Retinal and choroidal vascular networks, although distinct entities, seem functionally interconnected: varying the degree of perfusion may be a mutual compensatory mechanism in response to an ischemic injury.

Choroidal thickness changes in non-treated eyes of patients with diabetes: swept-source optical coherence tomography study.

AIMS: To measure choroidal thickness (CT) in diabetic eyes and its correlation with metabolic status and the severity of diabetic retinopathy (DR). MATERIALS AND METHODS: Prospective cross-sectional study using swept-source optical coherence tomography. CT maps of 96 treatment naïve eyes of 48 patients with diabetes were compared to 46 eyes of 23 healthy controls. CT changes and their relation to diabetes, age, gender, disease duration, hypertension (HT), hemoglobin A1c level, type and severity of DR were evaluated. RESULTS: A significantly thinner choroid was measured in patients with diabetes compared to controls (p < 0.009). In the diabetic group age, gender, disease duration and HT were significantly correlated with CT in univariable regression models (p < 0.05). In multivariable analysis, the duration of diabetes significantly negatively correlated with CT (p = 0.02). According to analysis of variance, there was a significant difference among means of CT in different stages of DR (p = 0.002), with thinner CT in cases with more advanced DR. In a multivariable predictive model, thinner CT was associated with an increased risk for the presence of DR (p = 0.02). CONCLUSIONS: Diabetes mellitus itself and the severity of DR affect CT significantly, even after adjusting for the effects of confounding systemic factors. Disease duration seems to be associated with a reduction of choroidal thickness. Decreased CT proved to be correlated with the severity of DR.

Association of choroidal thickness with early stages of diabetic retinopathy in type 2 diabetes.

AIM: To assess the correlation between choroidal thickness (CT) and the early stages of diabetic retinopathy (DR) in type 2 diabetic patients. METHODS: We divided 83 diabetic patients (51-80 years of age; 50 females) into non diabetic retinopathy group (NDR) and mild/moderate nonproliferative diabetic retinopathy (NPDR) group, and compared them with 26 non-diabetic control subjects (51-78 years of age; 16 females). Subfoveal choroidal thickness (SFCT) and parafoveal choroidal thickness (PFCT) were measured using enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT). Ocular health status, disease duration, body mass index, and hemoglobin A1c (HbA1c) were recorded. RESULTS: The mean ages of the NDR, NPDR, and control groups were 68.0±6.9y, 67.8±6.4y, and 65.1±6.3y, respectively (P=0.17). Pearson correlation of the right and left eyes for the control subjects was 0.95 and for the NDR subjects was 0.93. SFCT for the right eyes of the controls was 252.77± 41.10 µm, which was significantly thicker than that of the right eyes in NDR group (221.51±46.56 µm) and the worse eyes of the NPDR group (207.18±61.87 µm; ANOVA, P<0.01). In the diabetic patients pooled together, age was the only variable significantly associated with SFCT (multiple linear regression analysis, P=0.01). CONCLUSION: CT decreased significantly in the NDR and mild/moderate NPDR eyes compared with the control eyes. Age is significantly associated with SFCT in the diabetic patients. Diabetic choroidopathy may be present before clinical retinopathy.

Choroidal microvascular proliferation secondary to diabetes mellitus.

Diabetes is a common endocrine disorder associated with peripheral microvascular diseases such as proliferative retinal microangiopathy (or diabetic retinopathy), which may lead to blindness. Unfortunately, diabetic microvascular abnormalities in the choroid are underestimated in clinical practice. Recent literature has revealed that the severity of diabetic retinopathy is aggravated by choroidopathy resulting from hyperglycemia. Here, we introduce a case of diabetic retinopathy with choroidal neovascularization membrane but without signs of retinal microvascular proliferation or drusen. We investigated the pathogenesis of choroidal microvascular proliferation secondary to diabetes. We postulate that choroidal neovascularization is an intraocular microvascular complication of diabetes mellitus. Intravitreal anti-vascular endothelial growth factor therapy may be a treatment option for microvascular proliferation in both retina and choroids.