Catarina Neves

Quantification of Retinal Microvascular Density in Optical Coherence Tomographic Angiography Images in Diabetic Retinopathy

Importance Quantitative measurements based on optical coherence tomographic angiography (OCTA) may have value in managing diabetic retinopathy (DR), but there is limited information on the ability of OCTA to distinguish eyes with DR. Objective To evaluate the ability of measurements of retinal microvasculature using OCTA to distinguish healthy eyes from eyes with DR. Design, Setting, and Participants In this prospective cross-sectional study, OCTA was used to examine the eyes of participants with type 2 diabetes with or without DR and the eyes of participants without diabetes from September 17, 2015, to April 6, 2016. Density maps based on superficial retinal layer (SRL) and deeper retinal layer (DRL) images were generated after a method to remove decorrelation tails was applied to the DRL images. Exposures Both eyes of each participant were examined by means of a 3-mm OCTA scan and 7-field fundus photography using the Diabetic Retinopathy Severity Scale. Main Outcomes and Measures Two measures were examined: perfusion density, based on the area of vessels, and vessel density, based on a map with vessels of 1-pixel width. The size of the foveal avascular zone was also calculated automatically, and so was the area under the receiver operating characteristic curve. Results A total of 50 eyes from 26 participants with diabetes (10 women and 16 men; mean [SD] age, 64.9 [7.5] years) and 50 healthy eyes from 25 participants without diabetes (14 women and 11 men; mean [SD] age, 64.0 [7.1] years) were imaged. All participants were white. Vessel density measured in the SRL had the highest area under the receiver operating characteristic curve (0.893 [95% CI, 0.827-0.959]), compared with perfusion density in the SRL (0.794 [95% CI, 0.707-0.881]), foveal avascular zone area (0.472 [95% CI, 0.356-0.588]), and vessel density in the DRL (0.703 [95% CI, 0.601-0.805]). Vessel density in the SRL negatively correlated with best-corrected visual acuity (r = –0.28; P = .05) and severity of DR (r = –0.46; P = .001). Density metrics correlated with age. No correlation was detected between vascular density or foveal avascular zone metrics and hemoglobin A1C or duration of diabetes. Conclusions and Relevance Vessel density measured by OCTA provides a quantitative metric of capillary closure that correlates with severity of DR and may allow staging, diagnosis, and monitoring that do not require subjective evaluation of fundus images.

Retinal Layer Location of Increased Retinal Thickness in Eyes with Subclinical and Clinical Macular Edema in Diabetes Type 2

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.

Comparison of diabetic retinopathy classification using fluorescein angiography and optical coherence tomography angiography

Purpose To analyse and compare the classification of eyes with diabetic retinopathy using fluorescein angiography (FA) and optical coherence tomography angiography (OCTA) performed either with AngioPlex or AngioVue. Methods This was an observational cross-sectional study of 50 eyes from 26 diabetic subjects. Two independent graders classified the FA angiograms, to assess the presence and severity of several characteristics according to the ETDRS Report 11, and a similar evaluation was performed for each 3×3 mm OCTA image from the superficial retinal layer and for the full retina slab. Results Percentages of non-gradable images for the outline of foveal avascular zone (FAZ) in the central subfield (CSF) were 29.0% for FA, 12.0% for AngioVue and 3.0% for AngioPlex. For capillary loss, percentages of non-gradable images in the CSF were 25.0% for FA, 11% for AngioVue and 0.0% for AngioPlex. For the inner ring (IR), percentages of non-gradable images were 12.5% for FA, 11.5% for AngioVue and 0.5% for AngioPlex. Agreement between graders was substantial for outline of FAZ. For capillary loss, the agreement was fair for the CSF, and moderate for the IR. Conclusions The OCTA allows better discrimination of the CSF and parafoveal macular microvasculature than FA, especially for FAZ disruption and capillary dropout, without the need of an intravenous injection of fluorescein. In addition, FA had also a higher number of non-gradable images. The OCTA can replace with advantage the FA, as a non-invasive and more sensitive procedure for detailed morphological evaluation of central macular vascular changes. Trial registration number NCT02391558, Pre-results.

Characterization of Retinal Disease Progression in a 1-Year Longitudinal Study of Eyes With Mild Nonproliferative Retinopathy in Diabetes Type 2.

PURPOSE To identify eyes of patients with diabetes type 2 that show progression of retinal disease within a 1-year period using noninvasive techniques. METHODS Three hundred seventy-four type 2 diabetic patients with mild nonproliferative diabetic retinopathy (Early Treatment Diabetic Retinopathy Study [ETDRS] level 20 or 35) were included in a 12-month prospective observational study to identify retinopathy progression. Four visits were scheduled at 0, 3, 6, and 12 months. Microaneurysm (MA) activity using the RetmarkerDR and retinal thickness using spectral-domain optical coherence tomography (SD-OCT) were assessed by a central reading center at all visits and ETDRS severity level in the first and last visits. RESULTS Three hundred thirty-one eyes/patients completed the study. Microaneurysm formation rate greater than or equal to 2 was present in 68.1% of the eyes and MA turnover greater than or equal to 6 in 54.0% at month 6. Higher MA turnover values were registered in eyes that showed progression in ETDRS severity level (P < 0.03). There were also significant correlations between increased microaneurysm activity and increases in retinal thickness. Spectral-domain OCT identified clinical macular edema in 24 eyes/patients (6.7%) and subclinical macular edema in 104 eyes/patients (28.9%) at baseline. Progression of retinal thickening was registered in eyes that had either subclinical or clinical macular edema at baseline. CONCLUSIONS Changes in MA activity measured with RetmarkerDR and in central retinal thickness in eyes with mild nonproliferative diabetic retinopathy and diabetes type 2 are able to identify eyes at risk of progression. These eyes/patients should be selected for inclusion in future clinical trials of drugs targeted to prevent diabetic retinopathy progression to vision-threatening complications. (ClinicalTrials.gov number, NCT01145599.)

One-Year Progression of Diabetic Subclinical Macular Edema in Eyes with Mild Nonproliferative Diabetic Retinopathy: Location of the Increase in Retinal Thickness

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.

Screening for Diabetic Retinopathy in the Central Region of Portugal. Added Value of Automated 'Disease/No Disease' Grading.

Purpose: To describe the procedures of a nonmydriatic diabetic retinopathy (DR) screening program in the Central Region of Portugal and the added value of the introduction of an automated disease/no disease analysis. Methods: The images from the DR screening program are analyzed in a central reading center using first an automated disease/no disease analysis followed by human grading of the disease cases. The grading scale used is as follows: R0 - no retinopathy, RL - nonproliferative DR, M - maculopathy, RP - proliferative DR and NC - not classifiable. Results: Since the introduction of automated analysis in July 2011, a total of 89,626 eyes (45,148 patients) were screened with the following distribution: R0 - 71.5%, RL - 22.7%, M - 2.2%, RP - 0.1% and NC - 3.5%. The implemented automated system showed the potential for human grading burden reduction of 48.42%. Conclusions: Screening for DR using automated analysis allied to a simplified grading scale identifies DR vision-threatening complications well while decreasing human burden.

Relevance of Retinal Thickness Changes in the OCT Inner and Outer Rings to Predict Progression to Clinical Macular Edema: An Attempt of Composite Grading of Macular Edema

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.

Multimodal Evaluation of the Fellow Eye of Patients with Retinal Angiomatous Proliferation

Introduction: We conducted a multimodal, cross-sectional evaluation. Methods: Eyes were divided into 4 study groups: controls, early/intermediate age-related macular degeneration (AMD), fellow eyes of retinal angiomatous proliferation (RAP), and RAP eyes. Patients were evaluated with spectral-domain optical coherence tomography (OCT), enhanced depth imaging-OCT, and OCT angiography (OCTA). OCTA images were processed to generate maps of the vessel density and perfusion density of the superficial and deep retinal layers (SRL and DRL) and the choriocapillaris level (CL). The thickness of the outer nuclear layer and choroid was manually assessed. Results: We included 135 eyes of 100 patients (51 controls, 30 AMD, 42 RAP, and 12 fellow eyes). The fellow eyes showed a significantly lower vascular perfusion of the SRL, DRL, and CL (p < 0.02) than the early/intermediate AMD and control eyes did. Similarly, RAP eyes presented a lower vascular perfusion of the DRL and CL (p < 0.05). Besides, structural analyses of the fellow eyes and RAP eyes revealed a significantly higher prevalence of macular pigmentary changes, atrophy of the retinal pigment epithelium, hyperreflective “clumps” above flat drusen, amongst others, than early/intermediate AMD and control eyes (p < 0.05). Conclusion: We present the first report on the OCTA analysis of the fellow eye of patients with RAP. The reduced perfusion density and vessel density observed contributes, in association with clearly defined structural changes, to a wider characterization of RAP as a distinctive phenotype.

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