Central and peripheral changes in the retina and choroid in patients with diabetes mellitus without clinical diabetic retinopathy assessed by ultra-wide-field optical coherence tomography angiography

Detection of choroidal vascular features in diabetic patients without clinically visible diabetic retinopathy by optical coherence tomography angiography: A systemic review and meta-analysis

Researchers have explored choroidal features in the eyes of diabetic patients without clinically visible diabetic retinopathy (DM-NoDR) employing optical coherence tomography angiography (OCTA); however, the results are controversial. We systematically searched PubMed, Embase, and Ovid databases for OCTA studies comparing choroidal parameters between DM-NoDR eyes and healthy controls or non-proliferative diabetic retinopathy (NPDR) eyes. Outcomes included choriocapillaris (CC) perfusion density (PD), flow area (FA), and flow deficits (FD). 36 studies were finally included in the quantitative meta-analysis, involving 1,908 DM-NoDR eyes, 792 NPDR eyes, and 1,391 healthy control eyes. DM-NoDR eyes had significantly lower CC PD in the foveal region (P=0.0005) and superior parafoveal region (P=0.003) than healthy control eyes, but no significant difference was found in other parafoveal subregions (P>0.05). DM-NoDR eyes were also associated with increased CC FD (P<0.00001) and decreased CC FA (P<0.0001) in whole OCTA images with a 3×3 mm2 field of view (FOV). Compared with all-stage NPDR eyes, DM-NoDR eyes had higher CC PD in the foveal region (P<0.0001), parafoveal region (P<0.00001), and the whole OCTA images with a 6×6 mm2 FOV (P<0.00001). Early choroidal microvascular changes may precede clinically visible DR and can be detected early using OCTA in DM-NoDR eyes.

Modern Approach to Diabetic Retinopathy Diagnostics

This article reviews innovative diagnostic approaches for diabetic retinopathy as the prevalence of diabetes mellitus and its complications continue to escalate. Novel techniques focus on early disease detection. Technological innovations, such as teleophthalmology, smartphone-based photography, artificial intelligence with deep learning, or widefield photography, can enhance diagnostic accuracy and accelerate the treatment. The review highlights teleophthalmology and handheld photography as promising solutions for remote eye care. These methods revolutionize diabetic retinopathy screening, offering cost-effective and accessible solutions. However, the use of these techniques may be limited by insurance coverage in certain world regions. Ultra-widefield photography offers a comprehensive view of up to 80.0% of the retina in a single image, compared to the 34.0% coverage of the traditional seven-field imaging protocol. It allows retinal imaging without pupil dilation, especially for individuals with compromised mydriasis. However, they also have drawbacks, including high costs, artifacts from eyelashes, eyelid margins, and peripheral distortion. Recent advances in artificial intelligence and machine learning, particularly through convolutional neural networks, are revolutionizing diabetic retinopathy diagnostics, enhancing screening efficiency and accuracy. FDA-approved Artificial Intelligence-powered devices such as LumineticsCore™, EyeArt, and AEYE Diagnostic Screening demonstrate high sensitivity and specificity in diabetic retinopathy detection. While Artificial Intelligence offers the potential to improve patient outcomes and reduce treatment costs, challenges such as dataset biases, high initial costs, and cybersecurity risks must be considered to ensure safety and efficiency. Nanotechnology advancements further enhance diagnosis, offering highly branched polyethyleneimine particles with fluorescein sodium (PEI-NHAc-FS) for better fluorescein angiography or vanadium oxide-based metabolic fingerprinting for early detection.

Optical coherence tomography angiography in diabetic retinopathy: A major review

Diabetic retinopathy (DR) is characterized by retinal vasculopathy and is a leading cause of visual impairment. Optical coherence tomography angiography (OCTA) is an innovative imaging technology that can detect various pathologies and quantifiable changes in retinal microvasculature. We briefly describe its functional principles and advantages over fluorescein angiography and perform a comprehensive review on its clinical applications in the screening or management of people with prediabetes, diabetes without clinical retinopathy (NDR), nonproliferative DR (NPDR), proliferative DR (PDR), and diabetic macular edema (DME). OCTA reveals early microvascular alterations in prediabetic and NDR eyes, which may coexist with sub-clinical neuroretinal dysfunction. Its applications in NPDR include measuring ischemia, detecting retinal neovascularization, and timing of early treatment through predicting the risk of retinopathy worsening or development of DME. In PDR, OCTA helps characterize the flow within neovascular complexes and evaluate their progression or regression in response to treatment. In eyes with DME, OCTA perfusion parameters may be of predictive value regarding the visual and anatomical gains associated with treatment. We further discussed the limitations of OCTA and the benefits of its incorporation into an updated DR severity scale.

Ultra-Wide-Field Optical Coherence Tomography and Gaussian Curvature to Assess Macular and Paravascular Retinoschisis in High Myopia

PURPOSE

To evaluate the severity and related factors of macular retinoschisis (MRS) and paravascular retinoschisis (PVRS) in high myopia (HM) using ultra-wide-field optical coherence tomography (UWF-OCT) and a novel Gaussian curvature (K).

DESIGN

A cross-sectional study.

METHODS

Patients diagnosed with HM in Peking Union Medical College Hospital were recruited between January 2022 and November 2022. The presence and severity of retinoschisis, along with the three highest K values, were assessed using UWF-OCT and en face images. Logistic regressions were employed to identify factors associated with MRS, PVRS, and the severity of retinoschisis in the 24 × 20 mm scan region.

RESULTS

A total of 108 HM eyes from 55 patients were recruited. The highest Gaussian curvature (K1) was predominantly found in the vascular arcade (43, 40%). Multivariable logistic regression found that age and PVRS were significant risk factors for MRS occurrence (P < .05), while MRS and higher K1 were significantly associated with the presence of PVRS in HM patients (P < .05). The axial length (AL) and spherical equivalent were associated with the severity of MRS, while AL and K1 values were associated with the severity of retinoschisis in the 24 × 20 mm scan region (P < .05).

CONCLUSIONS

An association existed between large Gaussian curvature and the presence of MRS and PVRS, as well as the severity of retinoschisis in a wide field of view. UWF-OCT, which enables visualization of the central and peripheral retinal areas, holds promise as an imaging technique for the early detection of extrafoveal retinoschisis.

Advances in Structural and Functional Retinal Imaging and Biomarkers for Early Detection of Diabetic Retinopathy

Diabetic retinopathy (DR), a vision-threatening microvascular complication of diabetes mellitus (DM), is a leading cause of blindness worldwide that requires early detection and intervention. However, diagnosing DR early remains challenging due to the subtle nature of initial pathological changes. This review explores developments in multimodal imaging and functional tests for early DR detection. Where conventional color fundus photography is limited in the field of view and resolution, advanced quantitative analysis of retinal vessel traits such as retinal microvascular caliber, tortuosity, and fractal dimension (FD) can provide additional prognostic value. Optical coherence tomography (OCT) has also emerged as a reliable structural imaging tool for assessing retinal and choroidal neurodegenerative changes, which show potential as early DR biomarkers. Optical coherence tomography angiography (OCTA) enables the evaluation of vascular perfusion and the contours of the foveal avascular zone (FAZ), providing valuable insights into early retinal and choroidal vascular changes. Functional tests, including multifocal electroretinography (mfERG), visual evoked potential (VEP), multifocal pupillographic objective perimetry (mfPOP), microperimetry, and contrast sensitivity (CS), offer complementary data on early functional deficits in DR. More importantly, combining structural and functional imaging data may facilitate earlier detection of DR and targeted management strategies based on disease progression. Artificial intelligence (AI) techniques show promise for automated lesion detection, risk stratification, and biomarker discovery from various imaging data. Additionally, hematological parameters, such as neutrophil-lymphocyte ratio (NLR) and neutrophil extracellular traps (NETs), may be useful in predicting DR risk and progression. Although current methods can detect early DR, there is still a need for further research and development of reliable, cost-effective methods for large-scale screening and monitoring of individuals with DM.

OCT angiography 2023 update: focus on diabetic retinopathy

Optical coherence tomography angiography (OCTA) has become part of the clinical practice and its growing applications are in continuous development. Coherently with the growing concern about the human and economic cost of diabetes, diabetic retinopathy (DR) was the most popular topic for OCTA studies in the past year. The analysis of the literature reveals that applications of OCTA in DR are in continuous growth. In particular, ultrawide field (UWF) OCTA and artificial intelligence (AI) based on OCTA images are affirming as the new frontiers of scientific research in the field. Diagnostic accuracy of AI methods based on OCTA is equal or superior to the one based on OCT methods and also bears potential to detect systemic associations. UWF OCTA is noninvasive method that is reaching similar accuracy of FA in detection of neovascularization and intraretinal microvascular abnormalities (IRMAs) and has allowed better characterization of microvascular peripherical changes in DR. Lastly, deep capillary plexus (DCP) characteristics seem to play a pivotal role in the development of diabetic macular edema (DME) and refinement of biomarkers for different phenotypes of DME and diabetic macular ischemia (DMI) is currently on its way.

The clinical evaluation of a widefield lens to expand the field of view in optical coherence tomography (OCT-A)

This study aimed to evaluate the clinical benefits of incorporating a widefield lens (WFL) in optical coherence tomography angiography (OCT-A) in patients with retinal vascular diseases in comparison to standard single-shot OCT-A scans. Sixty patients with retinal vascular diseases including diabetic retinopathy (DR) and retinal vein occlusion (RVO) were recruited. OCT-A imaging (PlexElite 9000) with and without WFL was performed in randomized order. The assessment included patient comfort, time, field of view (FoV), image quality and pathology detection. Statistical analysis included paired t-tests, Mann-Whitney U-tests and Bonferroni correction for multiple tests, with inter-grader agreement using the kappa coefficient. Using a WFL did not lead to statistically significant differences in DR and RVO group test times. Patient comfort remained high, with similar responses for WFL and non-WFL measurements. The WFL notably expanded the scan field (1.6× FoV increase), enhancing peripheral retinal visibility. However, image quality varied due to pathology and eye dominance, affecting the detection of peripheral issues in RVO and DR cases. The use of a WFL widens the scan field, aiding vascular retinal disease imaging with minor effects on comfort, time, and image quality. Further enhancements are needed for broader view angles, enabling improved quantification of non-perfused areas and more reliable peripheral proliferation detection.

Comparative study of the vascular structures of the retina and choroid in Chinese Han and Uygur populations with proliferative diabetic retinopathy: An OCTA study

BACKGROUND

To compare the vascular structures of the retina and choroid in Chinese Han and Uygur populations with proliferative diabetic retinopathy (PDR) using swept-source OCTA (SS-OCTA).

METHODS

Fifty-three eyes of 53 healthy volunteers (25 from Hans and 28 from Uygurs) and 40 eyes of 40 PDR patients (20 from Hans and 20 from Uygurs) were included. Retinal and choroidal parameters, including thickness, vessel flow density (VFD), foveal avascular zone (FAZ) area, choroidal vascularity volume and index (CVV and CVI) were evaluated.

RESULTS

Compared with the respective controls, superficial capillary plexus (SCP)-VFD and deep capillary plexus (DCP)-VFD, the areas of FAZ in SCP and DCP were significantly decreased in both Han and Uygur PDR patients. choroidal parameters analysis found that Uygur controls had substantially higher choroidal thickness (CT) than Han controls (p = 0.020) and PDR eyes showed significantly decreased CT. Both races with PDR exhibited significantly reduced choriocapillaris layer-VFD, large and medium choroidal vessel (LMCV) layer-VFD, CVV and CVI, however, Uygur PDR patients had significant lower LMCV layer-VFD, CVV and CVI compared to Han PDR patients. Diabetes duration was the most significant factor affecting CVV and CVI.

CONCLUSION

Both Han and Uygur PDR patients had significantly lower CT and decreased vessel densities compared to controls, but the Uygur PDR patients had more severe choroidal damage than Han PDR patients, which is most likely related to worse visual prognosis. These findings indicate that more frequent screenings and prompt therapy are urgent for Uygur PDR patients.

Changes in the choroid detected by ultrawide-field optical coherence tomography angiography in type 2 diabetes mellitus patients without diabetic retinopathy

AIM

The study objective was to investigate the choroidal changes in type 2 diabetes mellitus (T2DM) patients without diabetic retinopathy (DR).

METHODS

This was a cross-sectional study. Controls without diabetes and T2DM patients without DR (NDR) were included. Ultrawide-field (24 × 20 mm2) optical coherence tomography angiography (OCTA) was performed to analyse choroidal thickness and vessel density. All OCTA images were divided into 3 × 3 grids. The grid centre was considered the central area, while the rest was defined as the peripheral area.

RESULTS

No differences between groups were observed in the flow density of the choriocapillaris (CC), choroidal thickness (ChT) and choroidal vascular index (CVI) of the large and medium choroidal vessel (LMCV) in the central area. In the eight peripheral areas, the mean flow density of the CC did not differ between the groups, while the mean CVI and ChT were decreased in the NDR group (P< 0.05). In each peripheral area, the mean CVI and ChT were decreased in the NDR group (P< 0.05, except in the infratemporal area and nasal area for ChT and in the infratemporal area for CVI). In the correlation analysis, both mean peripheral CVI and ChT correlated with age and the duration of diabetes.

CONCLUSION

Early choroidal lesions tended to be peripheral in the LMCV in patients with diabetes without DR and correlated with age and the duration of diabetes.