Multimodal Retinal Imaging in Patients with Diabetes Mellitus and Association with Cerebrovascular Disease

Deep learning assisted retinal microvasculature assessment and cerebral small vessel disease in Fabry disease

PURPOSE

The aim of this study was to assess retinal microvascular parameters (RMPs) in Fabry disease (FD) using deep learning, and analyze the correlation with brain lesions related to cerebral small vessel disease (CSVD).

METHODS

In this retrospective case control study, fundus images from 27 FD patients and 27 age- and sex-matched healthy subjects were collected. RMPs, encompassing diameter, density, symmetry, bifurcation, and tortuosity, were quantified. Laboratory examination results, Mainz severity score index (MSSI) scores, and a brain magnetic resonance imaging scan for CSVD scores were extracted and their relationships with RMPs was analyzed.

RESULTS

Utilizing artificial intelligence-assisted analysis, compared with controls, FD patients exhibited reduced diameter (p = 0.001 for central retinal artery equivalent, p = 0.049 for central retinal vein equivalent), density (p < 0.001 for vessel area density, p = 0.001 for length density), fractal dimension (p < 0.001), and heightened arteriolar and venular asymmetry ratios (p = 0.002 and p = 0.037, respectively), venular curvature tortuosity (p = 0.037), and simple tortuosity (p = 0.037) in retinal microvascular networks. Gender-based differences in RMPs were observed among FD patients. Furthermore, RMPs were significantly associated with disease markers such as plasma globotriaosylsphingosine and α-galactosidase A activity, as well as MSSI scores. Notably, there was a significant negative correlation between the arteriolar asymmetry ratio and CSVD-related scores (age-related white matter changes: r =  - 0.683, p = 0.001; Fazekas: r =  - 0.673, p = 0.001; Lacuna: r =  - 0.453, p = 0.045; small vessel diseases: r =  - 0.721, p = 0.012; global cortical atrophy: r =  - 0.582, p = 0.009).

CONCLUSIONS

Fabry disease patients demonstrated increased vascular tortuosity and asymmetry, reduced density and diameter, and a simpler fractal dimension in retinal microvasculature. These microvascular characteristics may serve as preliminary indicators for assessing brain lesions and could represent potential novel biomarkers for CSVD, aiding in the monitoring of FD severity and progression.

Laser-Based Therapy Approaches in the Retina: A Review of Micropulse Laser Therapy for Diabetic Retinopathy

PURPOSE

This review aims to elucidate the mechanisms and clinical utility of subthreshold micropulse laser (SML) therapy in the context of retinal care. Subthreshold or "nondestructive" laser therapy encompasses treatment modalities that induce minimal or no harm to retinal or choroidal tissue and leave no visible sings post-application, while achieving clinical efficacy.

METHODS

A comprehensive review of literature sourced from databases including PubMed, Medline, Embase, Cochrane, and Web of Science was conducted, focusing on articles published before February 2024, and discussing the contemporary use of SML therapy in treating diabetic retinopathy (DR).

RESULTS

The review presents evidence from scientific literature supporting SML therapy as a viable therapeutic approach for management of DR. Across numerous studies, SML therapy has demonstrated safety and additional therapeutic efficacy without causing damage to underlying retinal tissue.

CONCLUSION

Subthreshold laser treatment emerges as a safe strategy for addressing DR. Numerous studies have shown its additional efficacy to anti-VEGF pharmacotherapy, which is the currently approved monotherapy for complications of DR. Ongoing research and clinical investigations aim to further elucidate the mechanisms and optimize the therapeutic advantages of this technology.

Severity of Disorganization of Retinal Layers and Visual Function Impairment in Diabetic Retinopathy

PURPOSE

To evaluate best-corrected visual acuity (BCVA), retina sensitivity (RS), and fixation impairment by microperimetry (MP) due to the presence and severity of disorganization of retinal inner and outer layers (DRIL/DROL) and ischemia in OCT/OCT angiography (OCTA) in diabetic retinopathy (DR).

DESIGN

Retrospective case-control study.

SUBJECTS

Seventy-six eyes (65 patients) with DR were analyzed. Major exclusion criteria were: center-involving diabetic macular edema (DME), significant media opacity, nondiabetic macular pathology, and active proliferative DR. Patients with DRIL and DROL within central 3 mm were enrolled as cases. Patients with DR and no retina disorganization were considered as controls.

METHODS

A detailed grading of MP and OCT/OCTA images using Image J software, and specific Image Manipulation Program was applied to colocalize the presence of retina disorganization and RS. Best-corrected visual acuity and RS were correlated with the disorganization of retina layers' characteristics and grading (grade 1-DRIL; grade 2-DROL; grade 3-DROL plus, with involvement of the ellipsoid zone). The same procedure of colocalization was applied to the vascular layers on OCTA using MATLAB.

MAIN OUTCOME MEASURES

Correlation between BCVA and MP parameters with disorganization of retina layers grading and OCTA parameters.

RESULTS

Best-corrected visual acuity, mean RS within 1 mm and central 3 mm (overall RS [oRS]), perfusion density, vessel density, and geometric perfusion deficit in intermediate and deep capillary plexuses were lower in cases versus controls (P < 0.001). Mean RS within 1 mm (21.4 decibels [dB] ± 2.4 vs. 13.8 dB ± 5.4, P = 0.002), oRS (22.0 dB ± 2.1 vs. 14.4 dB ± 4.6, P < 0.001), and BCVA (76.1 ± 7.4 vs. 61.2 ± 20.4 ETDRS letters; P = 0.02), had a significant decrease from grade 1 to grade 3 retina disorganization. Choriocapillaris flow voids (CC-FVs) increased from grade 1 to grade 3 (DROL plus) (P = 0.004). Overall retina sensitivity and CC-FV were identified as significant predictors of retina disorganization grade with an adjusted coefficient of determination, R2 = 0.45. Cases had more dense scotomas (P = 0.03) than controls with a positive correlation between the worsening of fixation stability and the severity of DRIL/DROL (P = 0.04).

CONCLUSIONS

Microperimetry and BCVA documented a reduction in visual function in patients with DR and disorganization of retina layers at different grades, with greater functional impairment when outer retina layers and photoreceptors are involved. The severity of retina disorganization and the presence of ischemia could serve as a potential biomarker of functional impairment.

FINANCIAL DISCLOSURES

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Clinical Features Related to OCT Angiography Artifacts in Patients with Diabetic Macular Edema

PURPOSE

To investigate the frequency and type of artifacts on OCT angiography (OCTA) images and the relationship with clinical features in eyes with diabetic macular edema (DME).

DESIGN

Retrospective, cross-sectional comparative study.

SUBJECTS

One hundred ninety-two eyes of 140 patients with DME were included.

METHODS

Medical records, OCT and OCTA images (Spectralis), and ultrawidefield color fundus photographs (Optos plc) were evaluated.

MAIN OUTCOME MEASURES

The frequency of artifact types (segmentation, motion, projection artifact, and low signal) was determined. The relationships between artifact types and clinical features such as best-corrected visual acuity (BCVA), mean central retinal thickness (CRT), foveal avascular zone (FAZ) area, perimeter, circularity index, perfusion density (PD), vessel density (VD), fractal dimension (FD) in the superficial capillary plexus, intermediate capillary plexus (ICP), and deep capillary plexus (DCP), flow voids (FVs) in the choriocapillaris, presence of hard exudate (HE), and cataract were determined.

RESULTS

The mean age was 71.6 ± 11.4 years, and 86 (61.4%) out of 140 were men. Artifacts were present in 63 (32.8%) of 192 eyes. Twenty-nine (15.1%) eyes had segmentation artifacts, 12 (6.3%) had motion artifacts, 11 (5.7%) had projection artifacts, and 18 (9.4%) had low signal. Best-corrected visual acuity, PD, VD, and FD in ICP and DCP were significantly lower; and CRT, FAZ area and perimeter in ICP and DCP, and presence of cystoid macular edema, HE, and cataract were higher in eyes with artifacts versus eyes without artifacts (P < 0.05 for each). Multivariate linear regression analysis showed a significant association between segmentation artifacts and decreased BCVA (odds ratio [OR], 5.277; P = 0.02), increased CRT (OR, 1.015; P < 0.001), increased area of FAZ in DCP (OR, 6.625; P = 0.02), and increased perimeter of FAZ in DCP (OR, 1.775; P < 0.04); there was also a significant association between projection artifacts and presence of HE (OR, 2.017; P = 0.02) and between motion artifacts and presence of cataract (OR, 4.102; P = 0.01).

CONCLUSIONS

OCT angiography artifacts were present in one third of DME eyes, with segmentation artifacts being the most frequent type. Determining OCTA artifacts is crucial to ensure accurate clinical evaluation. These data could help in developing more standardized clinical protocols for image acquisition and interpretation used in clinical practice and research.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Prevalence of peripheral retinal findings in retinal patients using ultra-widefield pseudocolor fundus imaging

Ultra-widefield retinal imaging is increasingly used in ophthalmology and optometry practices to image patients identifying peripheral abnormalities. However, the clinical relevance of these peripheral retinal abnormalities is unclear. This cross-sectional study aims to firstly validate a new grading system, secondly, assess the prevalence of peripheral retinal abnormalities in retinal patients, and finally understand how peripheral findings may associate with retinal disease. Ultra-widefield pseudocolor fundus images were taken from the eyes of clinic patients. Demographic data and clinical diagnosis for each patient was noted. The grading system was validated using masked retinal specialists. Logistic regression identified associations between retinal disease and peripheral retinal findings. Using the grading system, inter-observer agreement was 76.1% with Cohen's Kappa coefficient 0.542 (p < 0.0001) and the test-retest agreement was 95.1% with Kappa 0.677(p < 0.0001). 971 images were included, with 625 eyes (64.4%) having peripheral abnormalities. Peripheral drusen was the most common abnormality (n = 221, 22.76%) and correlated with age-related macular degeneration (p < 0.001). Novel correlations were also identified between diabetic retinopathy and retinal pigmentation as well as pigmentary degeneration. This study provides a validated system for identifying peripheral abnormalities and adds to literature highlighting peripheral retinal associations with retinal disease which would benefit from further study.