Qualitative and quantitative evaluation of diabetic choroidopathy using ultra-widefield indocyanine green angiography

Stratified choroidal vascular structure in treatment-naïve diabetic retinopathy

OBJECTIVE

To analyze the anatomical choroidal vascular layers in topical treatment-naïve diabetic retinopathy (DR) eyes.

DESIGN

A retrospective, clinical case-control study.

METHODS

A total of 328 eyes from 228 patients with treatment-naive DR and 192 eyes matched for axial length from 174 healthy controls were enrolled in the study. Choroidal structure was quantitatively analyzed using enhanced depth imaging optical coherence tomography (EDI-OCT). Each choroidal vascular layer was divided into the choriocapillaris, Sattler's layer, and Haller's layer, and then the choroidal area (CA), luminal area (LA), stromal area (SA), and central choroidal thickness (CCT) were calculated using binarization techniques. The ratio of LA to CA was defined as the L/C ratio.

RESULTS

In the choriocapillaris, CA was significantly lower in the mild/moderate non-proliferative DR (mNPDR) group than in the control group, and SA was significantly higher in all DR groups (each P < 0.01). The L/C ratio was significantly lower in all DR groups than controls (P < 0.01). In Sattler's layer, CA, LA, and SA were significantly higher in the severe NPDR (sNPDR) and PDR groups than in the control group (P < 0.01). In Haller's layer, the L/C ratio was significantly high among the PDR groups (P < 0.05).

CONCLUSIONS

The choroidal parameters of DR patients by the binarization method were associated with the stage of DR, in which the choriocapillaris lumen decreased in all the DR stages. The expansion of CA seen in more advanced DR eyes mainly resulted from changes in the Sattler's and Haller's layers.

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.

Metabolic, Microvascular, and Structural Predictors of Long-Term Functional Changes Evaluated by Multifocal Electroretinogram in Type 1 Diabetes

BACKGROUND

This study aimed to analyze the potential pathogenic connection between metabolic factors, photoreceptor cell rearrangements, retinal microvascular perfusion, and functional parameters through multifocal electroretinography (mfERG) in type 1 diabetes mellitus (DM1).

METHODS

This prospective observational cohort study enrolled DM1 patients (40.5 ± 9.1 years) with mild nonproliferative diabetic retinopathy followed for 4 years. Patients were subjected to multimodal imaging, which included color fundus photography, optical coherence tomography (OCT), OCT angiography, adaptive optics (AO), and mfERG. OCTA slabs were analyzed using ImageJ software (software version 2.3.0/1.53f) to calculate perfusion density (PD) at both superficial (SCP) and deep (DCP) capillary plexuses, as well as flow deficit percentage (FD%) at the choriocapillaris (CC). To calculate cone metrics on AO at the parafovea, including cone density (CD), linear dispersion index (LDi), and heterogeneity packing index (Hpi%) in the parafovea, the images were post-processed using a MATLAB algorithm. The mfERG P1 implicit time (IT) and N1-P1 response amplitude density (RAD) from R1 (foveal area), R2 (parafoveal area), and the unified rings R1 + R2 were evaluated.

RESULTS

A total of 22 patients (22 eyes) were enrolled. No significant differences were noted in central mfERG amplitude and implicit time-averaged values (p > 0.05, all). The main factor influencing R1 IT was HbA1c, while R1 RAD was affected by Hpi and CC FD%. R1 + R2 IT was influenced by Hpi, LDi (p > 0.001, all), and modifications in the perfusion density in the SCP (p < 0.001) and DCP (p = 0.03) at the parafovea. In contrast, R1 + R2 RAD were associated with HbA1c (p = 0.02) and Hpi (p < 0.001).

CONCLUSIONS

Microvascular changes and glucometabolic factors are key elements influencing the long-term morphofunctional alterations at the photoreceptor level in DM1.

Fractal Changes of the Retinal Microvasculature in Birdshot Chorioretinopathy

BACKGROUND AND OBJECTIVE

Retinal vascular disorders are associated with lower fractal dimension (FD). We analyzed FD in birdshot chorioretinopathy (BSCR).

PATIENTS AND METHODS

This was a retrospective cohort study. We performed optical coherence tomography angiography (OCTA) and analyzed FD of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) using ImageJ. For each vascular layer, we analyzed the presence of BSCR, subjects' age, sex, and presence of diabetes mellitus to determine which may predict lower FD.

RESULTS

We compared 28 eyes (14 patients) with BSCR to 34 control eyes (17 patients). Mean FD of BSCR was lower in SCP (1.584 [± 0.126] vs 1.706 [± 0.118], P < 0.001), DCP (1.637 [± 0.134] vs 1.780 [± 0.096], P < 0.001), and CC (1.884 [± 0.063] vs 1.917 [± 0.047], P = 0.036). FD of SCP was lower per increasing year (0.005 [P = 0.014]). Male patients had lower FD-DCP (0.101 [P = 0.043]).

CONCLUSION

In BSCR, fractal analysis showed significant involvement of the SCP, DCP, and to a lesser extent the CC. [Ophthalmic Surg Lasers Imaging Retina 2024;55:646-651.].

Association between choroidal thickness and diabetic macular edema: a meta-analysis

AIMS

To evaluate the association between subfoveal choroidal thickness (SFCT) and diabetic macular edema (DME).

DESIGN

A systematic review and meta-analysis.

METHODS

A retrospective or prospective study comparing SFCT in diabetic retinopathy (DR) patients with and without DME was included. The data were collected from published studies retrieved from PubMed, Web of Science, Embase, Ovid Medline, and Cochrane Library. The final search was conducted on July 2, 2023. Heterogeneity was assessed using I2 statistics, and a random-effects model was used for the meta analysis. This study calculated the weighted mean difference (WMD) and 95% confidence interval (CI) for SFCT.

RESULTS

A total of 26 relevant studies were identified, involving a combined sample size of 3201 eyes (1302 DR-DME eyes and 1899 DR-no DME eyes). The results showed no significance between DR-DME and DR-no DME (WMD = - 3.57 μm; 95% CI -26.54 to 19.41 μm; P = 0.76). Sub-analysis based on nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) subgroups showed that the SFCT of NPDR-DME was significantly thinner than that of NPDR-no DME eyes (WMD = - 19.80 μm; 95% CI - 34.55 to - 5.04 μm; P = 0.009), while there was no significance in SFCT between PDR-DME and PDR-no DME (WMD = - 26.45 μm; 95% CI - 104.00 to 51.11 μm; P = 0.50).

CONCLUSION

The SFCT was thinner in NPDR-DME eyes compared to NPDR-no DME eyes. Thinning SFCT might cause retinal hypoxia, and play an important role in DME occurrence. Additionally, this study highlights the importance of considering DR grades and treatment history when evaluating SFCT between DME and no DME.

Glucose tolerance and insulin resistance/sensitivity associate with retinal layer characteristics: the LIFE-Adult-Study

AIMS/HYPOTHESIS

As the prevalence of insulin resistance and glucose intolerance is increasing throughout the world, diabetes-induced eye diseases are a global health burden. We aim to identify distinct optical bands which are closely related to insulin and glucose metabolism, using non-invasive, high-resolution spectral domain optical coherence tomography (SD-OCT) in a large, population-based dataset.

METHODS

The LIFE-Adult-Study randomly selected 10,000 participants from the population registry of Leipzig, Germany. Cross-sectional, standardised phenotyping included the assessment of various metabolic risk markers and ocular imaging, such as SD-OCT-derived thicknesses of ten optical bands of the retina. Global and Early Treatment Diabetic Retinopathy Study (ETDRS) subfield-specific optical retinal layer thicknesses were investigated in 7384 healthy eyes of 7384 participants from the LIFE-Adult-Study stratified by normal glucose tolerance, prediabetes (impaired fasting glucose and/or impaired glucose tolerance and/or HbA1c 5.7-6.4% [39-47 mmol/mol]) and diabetes. The association of optical retinal band characteristics with different indices of glucose tolerance (e.g. fasting glucose, area under the glucose curve), insulin resistance (e.g. HOMA2-IR, triglyceride glucose index), or insulin sensitivity (e.g. estimated glucose disposal rate [eGDR], Stumvoll metabolic clearance rate) was determined using multivariable linear regression analyses for the individual markers adjusted for age, sex and refraction. Various sensitivity analyses were performed to validate the observed findings.

RESULTS

In the study cohort, nine out of ten optical bands of the retina showed significant sex- and glucose tolerance-dependent differences in band thicknesses. Multivariable linear regression analyses revealed a significant, independent, and inverse association between markers of glucose intolerance and insulin resistance (e.g. HOMA2-IR) with the thickness of the optical bands representing the anatomical retinal outer nuclear layer (ONL, standardised β=-0.096; p<0.001 for HOMA2-IR) and myoid zone (MZ; β=-0.096; p<0.001 for HOMA2-IR) of the photoreceptors. Conversely, markers of insulin sensitivity (e.g. eGDR) positively and independently associated with ONL (β=0.090; p<0.001 for eGDR) and MZ (β=0.133; p<0.001 for eGDR) band thicknesses. These global associations were confirmed in ETDRS subfield-specific analyses. Sensitivity analyses further validated our findings when physical activity, neuroanatomical cell/tissue types and ETDRS subfield categories were investigated after stratifying the cohort by glucose homeostasis.

CONCLUSIONS/INTERPRETATION

An impaired glucose homeostasis associates with a thinning of the optical bands of retinal ONL and photoreceptor MZ. Changes in ONL and MZ thicknesses might predict early metabolic retinal alterations in diabetes.

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.