The decorrelation signals in optical coherence tomography angiography (OCTA) are derived from the flow of erythrocytes and concomitantly delineate the retinal vasculature. We compared the structural and functional characteristics of vascular lesions visualized in fluorescein angiography (FA), OCTA, and en-face OCT images in 53 eyes (28 patients) with diabetic retinopathy (DR). The foveal avascular zone (FAZ) areas in OCTA images in the superficial layer almost corresponded to those in FA images. The FAZ areas in the en-face OCT images in the superficial layer were smaller than those in the FA images and correlated with each other, which agreed with the finding that en-face OCT images often delineated the vascular structure in the nonperfused areas in FA images. Microaneurysms appeared as fusiform, saccular, or coiled capillaries in OCTA images and ringed, round, or oval hyperreflective lesions in en-face OCT images. OCTA and en-face OCT images detected 41.0 ± 16.1% and 40.1 ± 18.6%, respectively, of microaneurysms in FA images, although both depicted only 13.9 ± 16.4%. The number of microaneurysms in FA images was correlated with that in OCTA and en-face OCT images. Comparisons of these modalities showed the associations and dissociations between blood flow and vascular structures, which improves the understanding of the pathogenesis of DR.
Anti-vascular endothelial growth factor drugs are the first-line treatment for diabetic macular edema (DME), although the mechanism of the visual acuity (VA) improvement remains largely unknown. The association between photoreceptor damage and visual impairment encouraged us to retrospectively investigate the changes in the foveal photoreceptors in the external limiting membrane (ELM) and ellipsoid zone (EZ) on spectral-domain optical coherence tomography (SD-OCT) images in 62 eyes with DME treated with intravitreal ranibizumab (IVR) injections. The transverse lengths of the disrupted EZ and ELM were shortened significantly (P < 0.001 and P = 0.044, respectively) at 12 months. The qualitative investigation also showed restoration of the EZ and ELM lines on SD-OCT images. The EZ at 12 months lengthened in 34 of 38 eyes with discontinuous EZ and was preserved in 16 of 21 eyes with complete EZ at baseline. VA improvement was positively correlated with shortening of the disrupted EZ at 12 months (ρ = 0.463, P < 0.001), whereas the decrease in central subfield thickness was associated with neither VA improvement nor changes in EZ status (ρ = 0.215, P = 0.093 and (ρ = 0.209, P = 0.103, respectively). These data suggested that photoreceptor restoration contributes to VA improvement after pro re nata treatment with IVR injections for DME independent of resolved retinal thickening.
Anti-VEGF drugs are as the first-line therapies for diabetic macular edema (DME). In this study, we investigated the association between hyperreflective foci in the outer retinal layers and functional efficacy in DME patients who received intravitreal ranibizumab (IVR) injections. We retrospectively reviewed 77 eyes of 71 patients with DME treated with pro re nata IVR injections for at least 12 months. We evaluated how baseline hyperreflective foci in the outer retinal layers on spectral domain optical coherence tomography images were associated with an improvement in logarithm of the minimum angle of resolution visual acuity (logMAR VA) at 12 months. Forty-three eyes with hyperreflective foci in the outer retinal layers had greater VA improvement than 34 eyes without such foci at 12 months. Multivariate analyses demonstrated that both logMAR VA and hyperreflective foci in the outer retinal layers at baseline were associated with VA improvement. Structural analyses revealed that the central subfield thickness was decreased and that the ellipsoid zone of photoreceptors was improved more significantly in eyes with hyperreflective foci in the outer layers than eyes without such lesions. Baseline hyperreflective foci in the outer retinal layers predict the functional efficacy of IVR injections for DME. Diabetic macular edema (DME) leads to visual impairment in diabetic patients, mediated via the breakdown of blood-retinal barrier (BRB) and concomitant neuroglial dysfunction 1. Both basic and clinical researches have shown that vascular endothelial growth factor (VEGF) is a main regulator in the pathogenesis of DME, and anti-VEGF treatment has great effects on anatomical and functional outcomes in DME 2-5. Two major drugs neutralizing VEGF, ranibizumab and aflibercept, have been used as the first-line therapies for DME in many countries since the approval by the administrations. However, the magnitude of efficacy varies among each patient, indicating a need to find the prognostic factors for anti-VEGF treatment 6,7. Spectral domain optical coherence tomography (SD-OCT) has been introduced into the clinical setting and can be used to evaluate the anatomical changes in neuroglial tissues of the retinas 8-13. Post hoc analyses of a clinical trial found that the presence of subretinal fluid, one of the qualitative OCT findings, predicts better visual outcomes after intravireal ranibizumab (IVR) injections for DME 7. The qualitative or quantitative parameters in foveal cystoid spaces are also correlated with the short-term anatomical responses to medical treatments 14,15. Vitreoretinal abnormalities are a predictor of lower efficacy of IVR, whereas epiretinal membrane peeling is associated with greater visual acuity (VA) improvement in eyes that underwent vitrectomy 6,16. The ellipsoid zone of photoreceptors (EZ) line (or the junction of photoreceptor inner and outer segments[IS/OS]), a marker of foveal photoreceptor status, is restored at 12 months under anti-VEGF treatment, which may partly explain the functional efficac...
Diabetes induces lesions of the retinal and choroidal capillaries, which promote the pathogenesis of diabetic retinopathy (DR). The decorrelation signals in optical coherence tomography angiography (OCTA) represent the blood flow and vascular structure, and three-dimensional OCTA images enable individual capillary layers to be evaluated separately. The current study documented that en-face OCTA images revealed spots of flow void in the choriocapillaris layer in eyes with DR. Quantitative investigation demonstrated that non-flow areas within the central subfield (CSF) increased in eyes with more severe DR grades. The non-flow areas in the choriocapillaris layer were also associated with poorer visual acuity (VA) in all 108 eyes. A modest correlation was noted between the areas of flow void and poorer VA in 69 eyes without DME, whereas the non-flow areas were not related to VA or to CSF thickness measured by OCT in 39 eyes with DME. In 12 eyes with ischemic maculopathy, the choriocapillaris layer beneath the disrupted ellipsoid zone of the photoreceptor (EZ) had greater areas of flow void than did the area beneath an intact EZ. These data suggested that disrupted choroidal circulation has clinical relevance and contributes to the pathogenesis of DR.
PURPOSE. To investigate the nonperfused areas (NPAs) in each subfield segmented by large arterioles on wide-field swept-source optical coherence tomography angiography (SS-OCTA) images in diabetic retinopathy. METHODS. We retrospectively reviewed 101 consecutive eyes of 67 patients with severe nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR), for whom 12 3 12-mm SS-OCTA images centered on the optic disc were acquired. Both eyes were included in 34 patients. NPAs in the whole retinal layers were measured in each subfield segmented by large arterioles encompassing both the superficial and deep layers. We compared the percentage of NPAs between individual subfields, considering the overlapping of the feeding arterioles. RESULTS. Extramacular areas had higher rates of NPAs than macular areas in the inner (0.75-3 mm) and outer (3-5.5 mm) rings (P < 0.001 in both comparisons). The arteriolar arcades contacting the NPAs on the extramacular side were significantly longer than those contacting the NPAs on the macular side (P < 0.001). In particular, the extramacular areas between two arteriolar branches had a higher percentage of NPAs than those between two arterioles. The macular NPAs were greater in eyes with PDR than in those with severe NPDR, whereas there were no differences in the NPAs in the outer ring of extramacular areas. CONCLUSIONS. Wide-field OCTA images delineated that large arterioles residing in both the superficial and deep layers appear to be the perfusion boundaries, and the overlapping perfusion mediated via collateral vessels may affect the likelihood of diabetic NPAs in each subfield.
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