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Introduction: This study aimed to evaluate the association between macular optical coherence tomography angiography (OCT-A) metrics, characteristics of ultrawide field (UWF) imaging, and cerebrovascular disease in patients with diabetes mellitus (DM) with different stages of diabetic retinopathy (DR)., Methods: 516 eyes of 258 DM patients were enrolled in two centers (Milan and Belfast). UWF color fundus photos (CFPs) were obtained with Optos California (Optos, PLC) and graded for both DR severity and predominantly peripheral lesions presence (>50% of CFP lesions) by two independent graders. OCT-A (3 × 3 mm), available in 252 eyes of 136 patients, was used to determine perimeter, area, and circularity index of the foveal avascular zone and vessel density (VD); perfusion density (PD); fractal dimension on superficial, intermediate (ICP), and deep capillary plexuses; flow voids (FVs) in the choriocapillaris., Results: Out of 516 eyes, 108 eyes (20.9%) had no DR, and 6 eyes were not gradable. The remaining 402 eyes were as follows: 10.3% (53) had mild nonproliferative DR (NPDR), 38.2% (197) had moderate NPDR, 11.8% (61) had severe NPDR, and 17.6% (91) had proliferative DR. A worse DR stage was associated with a history of stroke (p = 0.044). Logistic regression analysis after taking into account sex, type of DM, age, DM duration, and OCT-A variables found that PD and VD on ICP were significantly associated with presence of stroke and DR severity., Conclusion: OCT-A metrics show an association with the presence of cerebrovascular complications, providing potentially useful parameters to estimate vascular risk in patients with DM., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Optical coherence tomography Angiography (OCT-A) represents a revolution in the noninvasive evaluation of retinal and choroidal circulation especially in detecting early clinical signs of diabetic retinal disease (DRD). With appropriate use, OCT-A characteristics and measurements have the potential to become new imaging biomarkers in managing and treating DRD. Major challenges include (a) provision of standardized outputs from different OCT-A instruments providing standardized terminology to correctly interpret data; (b) the presence of artifacts; (c) the absence of standardized grading or interpretation method in the evaluation of DRD, similar to that already established in fundus photography; and (d) establishing how OCT-A might be able to provide surrogate markers to demonstrate blood retinal barrier breakdown and vascular leakage, commonly associated with DRD. In fact, OCT-A guidelines for DRD are still evolving. The outputs of quantitative OCT-A data offer a unique opportunity to develop tools based on artificial intelligence to assist the clinicians in diagnosing, monitoring, and managing patients with diabetes. In addition, OCT-A has the potential to become a useful tool for the evaluation of cardiovascular diseases and different neurological diseases including cognitive impairment. This article written by the members of Diabetic Retinopathy expert committee of the European Vision Clinical Research network will review the available evidence on the use of OCT-A as an imaging biomarker in DRD and discuss the limits and the current application as well as future developments for its use in both clinical practice and research trials of DRD., (© 2021 The Author(s) Published by S. Karger AG, Basel.)

Purpose: To characterize the relevance of macular thickness changes in the inner and outer rings in the progression of macular edema in eyes/patients with diabetes type 2., Methods: A total of 374 type 2 diabetic patients with mild nonproliferative diabetic retinopathy (ETDRS levels 20-35) were included in a 12-month prospective observational study to identify retinopathy progression. Retinal thickness analyses were performed in 194 eyes/patients using Cirrus SD- OCT and 166 eyes/patients using Spectralis SD-OCT. The DRCR.net classification of subclinical and clinical macular edema was used. A composite grading of macular edema is proposed in this study., Results: A total of 317 eyes/patients completed the study. SD-OCT identified clinical macular edema in 24 eyes/patients (6.7%) and subclinical macular edema in 104 eyes/patients (28.9%) at baseline. Increased thickness of the central subfield is the best predictor for the development of clinical macular edema, with 85.7% sensitivity and 71.9% specificity (OR: 2.57, 95% CI: 0.82-7.99). However, the involvement of the inner and outer rings is a cumulative predictor of progression to clinical macular edema (OR: 8.69, 95% CI: 2.85-26.52)., Conclusions: A composite OCT grading of macular edema taking into account the retinal thickness changes in the inner and outer macular rings offers a simple way to characterize macular edema, with added clinical value., (© 2015 S. Karger AG, Basel.)

Purpose: To identify the retinal layer predominantly affected in eyes with subclinical and clinical macular edema in diabetes type 2., Methods: A cohort of 194 type 2 diabetic eyes/patients with mild nonproliferative diabetic retinopathy (ETDRS levels 20/35) were examined with Cirrus spectral-domain optical coherence tomography (OCT) at the baseline visit (ClinicalTrials.gov identifier: NCT01145599). Automated segmentation of the retinal layers of the eyes with subclinical and clinical macular edema was compared with a sample of 31 eyes from diabetic patients with normal OCT and an age-matched control group of 58 healthy eyes., Results: From the 194 eyes in the study, 62 had subclinical macular edema and 12 had clinical macular edema. The highest increases in retinal thickness (RT) were found in the inner nuclear layer (INL; 33.6% in subclinical macular edema and 81.8% in clinical macular edema). Increases were also found in the neighboring layers. Thinning of the retina was registered in the retinal nerve fiber, ganglion cells and inner plexiform layers in the diabetic eyes without macular edema., Conclusions: The increase in RT occurring in diabetic eyes with macular edema is predominantly located in the INL but extends to neighboring retinal layers indicating that it may be due to extracellular fluid accumulation., (© 2015 S. Karger AG, Basel.)

Purpose: To characterize the 1-year progression of retinal thickness (RT) increase occurring in eyes with subclinical macular edema in type 2 diabetes., Methods: Forty-eight type 2 diabetic eyes/patients with mild nonproliferative diabetic retinopathy (NPDR; levels 20 and 35 in the Early Treatment Diabetic Retinopathy Study) classified as presenting subclinical macular edema at baseline completed the 1-year follow-up period, from a sample of 194 followed in a 12-month observational and prospective study (ClinicalTrials.gov identifier: NCT01145599). Automated segmentation of the retinal layers in these eyes was performed, followed by verification and correction by a human grader., Results: The highest increase in RT over the 1-year follow-up period for the 48 eyes/patients with subclinical macular edema was found in the inner nuclear layer (INL). Progression to clinical macular edema was also associated with increased thickening of other retinal layers aside from the INL. The microvascular disease activity shown by microaneurysm (MA) turnover ≥6 was associated with progression from subclinical to clinical macular edema., Conclusions: Increases in RT occurring over a period of 1 year in diabetic eyes with mild NPDR and subclinical macular edema occur mainly in the INL. The development of clinical macular edema appears to be associated with increased thickening of other retinal layers and microvascular disease activity., (© 2015 S. Karger AG, Basel.)

Metamorphopsia is a common symptom in different macular disorders. Micropsia and macropsia are special types of metamorphopsia. Recent theories suggest that both retinal and cortical mechanisms are involved in the development and changes of metamorphopsia. Different functional tests have been proposed for the evaluation of metamorphopsia: from the Amsler grid to the hand-held mobile devices for home monitoring. This review addresses some new insights into the pathophysiology of metamorphopsia and different available tests for the evaluation of this symptom in most common macular disorders. The importance of quantification of metamorphopsia in macular diseases is confirmed by the most recent therapeutic approaches., (© 2015 S. Karger AG, Basel.)