Longitudinal analysis of microvascular perfusion and neurodegenerative changes in early type 2 diabetic retinal disease.

AIM: To prospectively monitor subclinical changes in capillary perfusion and retinal layer thickness in patients with type 2 diabetes and early diabetic retinal disease over 2 years. METHODS: In this longitudinal study we performed biannual retinal vascular imaging using optical coherence tomography angiography (RTVue) to analyse the foveal avascular zone (FAZ) area, perimeter, acircularity index (AI) and parafoveal superficial/deep vessel density (VD). Spectral-domain optical coherence tomography (Spectralis) was used to measure the thickness of nine macular layers and the peripapillary nerve fibre layer. RESULTS: Among 117 eyes (58 left) of 59 patients (21 female), 105 had no diabetic retinopathy (DR), 6 mild and 6 moderate non-proliferative DR at baseline. We found DR progression in 13 eyes at year 2. The FAZ area (+0.008±0.002 mm2/year, p<0.0001), perimeter (+0.036±0.010 mm/year, p=0.006) and AI (+0.005±0.002/year, p=0.0280) increased significantly. A pronounced decrease was found in the superficial (-1.425±0.290%/year, p<0.0001) but not the deep VD. Inner neuroretinal loss was confined to the ganglion cell (-0.539±0.150 µm/year, p=0.0004) and the inner plexiform layer (-0.361±0.127 µm/year, p=0.0045). In the outer retina, we observed a statistically significant decrease in thickness in the outer plexiform, photoreceptor layer and pigment epithelium of -0.921±0.161 µm/year, -0.325±0.139 µm/year and -0.385±0.084 µm/year, respectively. CONCLUSION: Subclinical signs of microangiopathy and neurodegeneration appear in parallel and are highly progressive even in the earliest stages of diabetic retinal disease. Trial registration number EudraCT20156000239634.

Identification of Subclinical Microvascular Biomarkers in Coronary Heart Disease in Retinal Imaging.

Purpose: Cardiovascular disease and foremost coronary heart disease (CHD) are the worldwide leading causes of death. The aim of this study was to use non-invasive, multimodel retinal imaging to define microvascular features in patients with and without coronary angiography (CA)-confirmed CHD. Methods: In this prospective, cross-sectional pilot study we included adult patients who presented to a tertiary referral center for elective CA due to suspected CHD. All patients underwent widefield fundus photography for retinopathy grading. Optical coherence tomography angiography was used to measure vessel density (VD) of the individual capillary plexuses in 6 × 6-mm macular volume scans. Adaptive optics imaging was performed to assess the first-order arteriolar lumen diameter (LD), total diameter (TD), wall-to-lumen ratio (WLR), and wall cross-section area, as well as to qualitatively describe vessel morphology. Results: Of the included 45 patients (13 females; 65 ± 10 years old), 27 were confirmed with CHD in elective CA. The most prevalent retinal vascular pathologies were arteriovenous nickings, focal arterial narrowings, and microaneurysms. VD in the superficial capillary plexus, deep capillary plexus, and choriocapillaris was lower in CHD patients, although the odds ratios were not significantly different from 1 (P = 0.06-0.92). Median arterial LD, TD, and WLR values were 98.3 µm (interquartile range [IQR] = 13.0), 122.9 µm (IQR = 17.6), and 0.26 µm (IQR = 0.07), respectively, with a trend toward a higher WLR in CHD patients. Conclusions: In a cardiovascular risk population, high-resolution quantitative and qualitative microvascular phenotyping in the retina may provide valuable subclinical indicators for coronary artery impairment, although larger clinical trials are needed. Translational Relevance: Subclinical retinal microvascular changes may serve as non-invasive, cost-effective biomarkers for risk stratification of patients with CHD.

PRESENCE OF PERIPHERAL LESIONS AND CORRELATION TO MACULAR PERFUSION, OXYGENATION AND NEURODEGENERATION IN EARLY TYPE II DIABETIC RETINAL DISEASE.

PURPOSE: The impact of peripheral retinal lesions (PL) visualized with ultra-wide-field imaging on diabetic retinopathy (DR) remains unclear. The purpose of this study was to assess the presence of PL and their association with macular microvasculopathy, metabolic dysfunction, and neurodegeneration in patients with Type II diabetes and early retinal disease. METHODS: Forty-five degree color fundus (Topcon) and 200° ultra-wide-field images (Optos) were assessed for the presence and severity of DR. Lesions anterior to the 45° were considered peripheral. The foveal avascular zone area, perimeter and acircularity index, and foveal full-retina and parafoveal superficial/deep complex vessel density were evaluated with RTVue optical coherence tomography angiography. Vessel oxygen saturation was measured with oximetry. Peripapillary retinal nerve fiber and individual macular retinal layer thicknesses were measured with Spectralis optical coherence tomography. RESULTS: Among the 161 eyes (80 left eyes) of 81 patients (34 female), 64 (39.8%) showed higher levels of DR on ultra-wide-field than on 45° fundus images (P < 0.0001). PL were identified in 97 eyes (60.3%) and in 59 among 115 eyes without central signs of DR. No significant correlation to biomarkers of central microvascular disease (foveal avascular zone/vessel density variables), oxygen saturation, and retinal layer thickness was found. CONCLUSION: Ultra-wide-field imaging helps to detect more eyes with early DR due to the detection of PL, which appear independently of biomarkers of macular microvascular impairment, metabolic function, and neuropathy in eyes without central signs of DR. These results suggest that the evaluation of the retinal periphery may become crucial in DR screening if PL are proven to influence disease outcomes.