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1.
Transl Vis Sci Technol ; 10(7): 31, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-34191017

RESUMO

Purpose: To investigate microvascular parameters that are related to the severity of diabetic retinopathy (DR) with optical coherence tomography angiography (OCTA). Methods: In total, 105 eyes from 105 diabetic patients were recruited in this prospective cross-sectional study, including 37 eyes with no clinical signs of DR (NoDR), 43 eyes with nonproliferative diabetic retinopathy (NPDR), and 25 eyes with proliferative diabetic retinopathy (PDR). Angiogram images from the parafoveal superficial capillary plexus (SCP), the deep capillary plexus (DCP), and the radial peripapillary capillary plexus were analyzed, and metrics were compared among groups. Multivariate regression analysis was used to identify the best OCTA parameters that could distinguish DR severity among groups. Results: Parafoveal vessel diameter index in the SCP and vessel density (VD) in the DCP showed the strongest correlation with the severity of DR (P < 0.01). Extrafoveal avascular area in the SCP was the parameter that could most distinguish NoDR from NPDR (P < 0.01) with sensitivity and specificity of 83.72% and 78.38%, respectively. VD in the DCP also was the most sensitive biomarker to distinguish NPDR from PDR (P < 0.01) with sensitivity and specificity of 84.00% and 79.07%, respectively. Conclusions: The microvascular changes in the SCP and DCP in DR may have different characteristics that could be identified with specific OCTA parameters. OCTA serves as a promising technology to discriminate eyes with different severity of DR. Translational Relevance: Our study investigated OCTA metrics and severity of DR. At different stages of DR, ophthalmologists may focus on specific OCTA parameters to predict the progression of retinopathy in individual patients.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Estudos Transversais , Retinopatia Diabética/diagnóstico por imagem , Angiofluoresceinografia , Humanos , Estudos Prospectivos , Vasos Retinianos/diagnóstico por imagem , Tomografia de Coerência Óptica
2.
Comput Biol Med ; 134: 104529, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34126283

RESUMO

Optical coherence tomography angiography (OCTA) and fluorescein angiography (FA) are two different vascular imaging modalities widely used in clinical practice to diagnose and grade different relevant retinal pathologies. Although each of them has its advantages and disadvantages, the joint analysis of the images produced by both techniques to analyze a specific area of the retina is of increasing interest, given that they provide common and complementary visual information. However, in order to facilitate this analysis task, a previous registration of the pair of FA and OCTA images is desirable in order to superimpose their common areas and focus the gaze on the regions of interest. Normally, this task is manually carried out by the expert clinician, but it turns out to be tedious and time-consuming. Here, we present a three-stage methodology for robust multimodal registration of FA and superficial plexus OCTA images. The first one is a preprocessing stage devoted to reducing the noise and segmenting the main vessels in both types of images. The second stage uses the vessel information to do an approximate registration based on template matching. Lastly, the third stage uses an evolutionary algorithm based on differential evolution to refine the previous registration and obtain the optimal registration. The method was evaluated in a dataset with 172 pairs of FA and OCTA images, obtaining a success rate of 98.8%. The best mean execution time of the method was less than 5 s per image.


Assuntos
Vasos Retinianos , Tomografia de Coerência Óptica , Algoritmos , Angiofluoresceinografia , Retina , Vasos Retinianos/diagnóstico por imagem
3.
Niger J Clin Pract ; 24(6): 911-918, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34121741

RESUMO

Aim: Diabetic retinopathy is a chronic progressive complication with neuronal cell and retinal microvascular involvement and is closely associated with blood sugar and blood pressure levels. Studies have shown that retinal neural dysfunction takes place before the microvascular changes in patients with Type 2 diabetes mellitus. The aim of this study is to compare the retinal microvascular changes of patients who are at the prediabetes stage and healthy volunteers. Method: Our study included 41 patients with prediabetes who were referred to the internal medicine outpatient clinic and 47 healthy volunteers. All patients underwent ophthalmologic examinations, including best visual acuity, intraocular pressure measurement, slit-lamp examination, and dilated fundus examination. Refractive error measurements were performed with the same automatic refractor-keratometer device. Typically, 3 × 3 mm macular images centered on foveola were obtained by using XR Avanti Optical Coherence Tomography Angiography with AngioVue (RTVue XR AVANTI, Optovue, Fremont, CA, USA) device. In the statistical analysis of the measurements, it was examined by Kolmogorov Smirnov test. Conditions expressed as IFG or IGT are considered as prediabetes; IFG is defined as fasting blood sugar to be between 100 and 125 mg/dL, while IGT is the condition in which the second hour value of the oral glucose tolerance test is 140-199 mg/dL. Results: There was no statistically significant difference between the control and pre-DM groups in terms of mean age. The distribution of males and females between groups was statistically similar (P = 0.087). In the pre-DM group, 24 (58.6%) patients had IFG, 16 (39.0%) had IFG + IGT, and 1 (2.4%) had IGT. There were no statistically significant differences between the groups for the nonflow area (NFA) and the foveal avascular zone (FAZ) area (P > 0.05). The mean values of superficial and deep capillary plexus (DCP) density were not statistically significant differences between the groups. No statistically significant difference was found between the control group and pre-DM group in terms of the mean measurements of clinical ocular findings (P > 0.05). Retinal thicknesses were also not statistically significant differences between the groups (P > 0.05). Conclusion: All of the retinal measurements of both patients with prediabetes and healthy volunteers are similar. We did not find any difference between prediabetes and control groups. The ophthalmologic examinations which contain best-visual acuity, intraocular pressure measurement, slit-lamp examination, and dilated fundus examination are similar.


Assuntos
Diabetes Mellitus Tipo 2 , Estado Pré-Diabético , Feminino , Angiofluoresceinografia , Fóvea Central , Humanos , Masculino , Vasos Retinianos/diagnóstico por imagem
4.
Indian J Ophthalmol ; 69(7): 1825-1832, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34146038

RESUMO

Purpose: To investigate the relationship between peripapillary vessel density (pVD) and visual field sensitivity (VFS) and between peripapillary retinal nerve fiber layer thickness (pRNFLT) and VFS, based on Garway-Heath sectorization in open-angle glaucoma patients. Methods: Sixty-six eyes of healthy subjects and 84 eyes of glaucoma subjects were included. All subjects underwent several eye examinations, including standard automated perimetry and optical coherence tomography angiography. Sectoral structure-function relationships based on the Garway-Heath sectorization were compared among normal subjects, the 'mild glaucoma,' and 'moderate-to-severe glaucoma' group. Multivariate analyses were performed for each sector to determine the factors related to VFS. The diagnostic abilities of vessel density parameters and RNFLT were evaluated by calculating the area under the receiver operating characteristic curves (AUROC). Results: The correlation between pVD-VFS and pRNFLT-VFS was statistically significant in the glaucoma group independent of the VFS sector. In the glaucoma group, VFS in the temportal sector was statistically related in a multivariate model to pVD, pRNFLT and age (R2 = 0.721; P = 0.007, < 0.001, .15, respectively). We found pRNFLT and age were significantly associated with VFS in glaucoma. The AUROC values of pVD in the inferotemporal sector of the total, mild, and moderate-to-severe glaucoma (0.843, 0.714, and 0.972, respectively) were comparable to pRNFLT in this sector (0.833, 0.718, 0.948, respectively). Conclusion: Since the relationship between pVD and VFS in the papillomacular area was significant, measuring pVD and RNFLT in the corresponding area will be valuable in expanding our pathophysiologic knowledge of the paracentral field defects in glaucoma.


Assuntos
Glaucoma de Ângulo Aberto , Disco Óptico , Estudos Transversais , Glaucoma de Ângulo Aberto/diagnóstico , Humanos , Pressão Intraocular , Fibras Nervosas , Células Ganglionares da Retina , Vasos Retinianos/diagnóstico por imagem , Tomografia de Coerência Óptica
5.
Transl Vis Sci Technol ; 10(6): 4, 2021 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-34111249

RESUMO

Purpose: Diabetic retinopathy (DR) is a common cause of vision loss in working age adults and presents changes in retinal vessel oxygenation and morphology. The purpose of this study was to test the hypothesis that there is an association of retinal vessel oxygen saturation with vessel density (VD) and tortuosity in DR. Methods: Ninety-five subjects were classified in the following groups: nondiabetic control (N = 25), no DR (N = 28), mild nonproliferative DR (NPDR; N = 21), moderate to severe NPDR (N = 14), or treated proliferative DR (PDR; N = 7). Retinal oximetry was performed to measure arterial and venous oxygen saturation (SO2A and SO2V) and calculate oxygen extraction fraction (OEF). Optical coherence tomography angiography (OCTA) was performed for measurements of VD and vessel tortuosity index (VTI). Results: There were statistically significant differences in SO2A and SO2V among groups (P ≤ 0.004). SO2A and SO2V were higher in the PDR group compared to the control group and SO2V was also higher in the moderate to severe NPDR group. VD differed significantly among groups (P = 0.003), whereas VTI was not significantly different (P = 0.22). Compared to the control group, VD was lower in moderate to severe NPDR and PDR groups. VD was also lower in the PDR group than that in the no DR group (P = 0.03). There was a significant correlation of VTI with SO2V (r = 0.32, P = 0.002) and OEF (r = -0.35, P = 0.001). Conclusions: Retinal vessel morphology, oxygenation, and tissue oxygen extraction were associated with each other in a cohort of subjects with and without DR. Translational Relevance: The findings of this study have the potential to improve clinical management of DR by providing better understanding of human disease pathophysiology and propelling future studies to identify multiple image-based biomarkers for improved disease diagnosis and monitoring.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Adulto , Retinopatia Diabética/diagnóstico , Humanos , Microvasos , Oxigênio , Vasos Retinianos/diagnóstico por imagem , Estudos Retrospectivos
6.
Transl Vis Sci Technol ; 10(7): 23, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-34137837

RESUMO

Purpose: To examine whether deep-learning denoised optical coherence tomography angiography (OCTA) images could enhance automated macular ischemia quantification in branch retinal vein occlusion (BRVO). Methods: This retrospective, single-center, cross-sectional study enrolled 74 patients with BRVO and 46 age-matched healthy subjects. The severity of macular ischemia was graded as mild, moderate, or severe. Denoised OCTA images were produced using a neural network model. Quantitative parameters derived from denoised images, including vessel density and nonperfusion area, were compared with those derived from the OCTA machine. The main outcome measures were correlations between quantitative parameters, and areas under receiver operating characteristic curves (AUCs) in classifying the severity of the macular ischemia. Results: The vessel density and nonperfusion area from denoised images were correlated strongly with the corresponding parameters from machine-derived images in control eyes and BRVO eyes with mild or moderate macular ischemia (all P < 0.001). However, no such correlation was found in eyes with severe macular ischemia. The vessel density and nonperfusion area from denoised images had significantly larger area under receiver operating characteristic curve than those derived from the original images in classifying moderate versus severe macular ischemia (0.927 vs 0.802 [P = 0.042] and 0.946 vs 0.797, [P = 0.022], respectively). There were no significant differences in the areas under receiver operating characteristic curve between the denoised images and the machine-derived parameters in classifying control versus BRVO, and mild versus moderate macular ischemia. Conclusions: A neural network model is useful for removing speckle noise on OCTA images and facilitating the automated grading of macular ischemia in eyes with BRVO. Translational Relevance: Deep-learning denoised optical coherence tomography angiography images could enhance automated macular ischemia quantification.


Assuntos
Aprendizado Profundo , Oclusão da Veia Retiniana , Estudos Transversais , Angiofluoresceinografia , Humanos , Isquemia/diagnóstico por imagem , Oclusão da Veia Retiniana/diagnóstico , Vasos Retinianos/diagnóstico por imagem , Estudos Retrospectivos , Tomografia de Coerência Óptica , Acuidade Visual
7.
BMC Ophthalmol ; 21(1): 259, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-34130654

RESUMO

BACKGROUND: Diabetic retinopathy is the most common microvascular complication of diabetes; however, early changes in retinal microvessels are difficult to detect clinically, and a patient's vision may have begun to deteriorate by the time a problem is identified. Optical coherence tomography angiography (OCTA) is an innovative tool for observing capillaries in vivo. The aim of this study was to analyze retinal vessel density and thickness changes in patients with diabetes. METHODS: This was a retrospective, observational cross-sectional study. Between August 2018 and February 2019, we collected OCTA data from healthy participants and diabetics from the First Affiliated Hospital of Harbin Medical University. Analyzed their retinal vessel density and thickness changes. RESULTS: A total of 97 diabetic patients with diabetes at different severity stages of diabetic retinopathy and 85 controls were involved in the experiment. Diabetic patients exhibited significantly lower retinal VD (particularly in the deep vascular complexes), thickening of the neurosensory retina, and thinning of the retinal pigment epithelium compared with controls. In the control group, nondiabetic retinopathy group and mild diabetic retinopathy group, superficial VD was significantly correlated with retinal thickness (r = 0.3886, P < 0.0001; r = 0.3276, P = 0.0019; r = 0.4614, P = 0.0024, respectively). CONCLUSIONS: Patients with diabetes exhibit ischemia of the retinal capillaries and morphologic changes in vivo prior to vision loss. Therefore, OCTA may be useful as a quantitative method for the early detection of diabetic retinopathy.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Estudos Transversais , Retinopatia Diabética/diagnóstico por imagem , Angiofluoresceinografia , Fundo de Olho , Humanos , Vasos Retinianos/diagnóstico por imagem , Estudos Retrospectivos , Tomografia de Coerência Óptica
8.
Vestn Oftalmol ; 137(3): 97-104, 2021.
Artigo em Russo | MEDLINE | ID: mdl-34156784

RESUMO

One distinctive pathological sign of chronic kidney disease (CKD) is microcirculatory disorders, which mark it as a microvascular disease. Similarity in the blood supply of the retina and kidneys, in the anatomy of their vascularization lead to identical complications in these organs. The retinal-choroidal microvascular system is easily accessible for clinical and morphological assessment and can be examined by the reproducible and non-invasive method - optical coherence tomography (OCT) and OCT angiography (OCTA). The study of significant diagnostic tomographic retinal biomarkers in CKD and monitoring of their changes are of great clinical importance. The article presents clinical cases of changes in the retina and choroid depending of the stage of CKD. Retinal microvascular changes precede functional impairment. A significant decrease in retinal and choroidal thickness correlates with a decrease in the glomerular filtration rate (GFR) and the degree of albumin excretion in the urine. All clinical cases were observed to exhibit retinal microcirculation disorders, capillary rarefaction in both capillary plexuses accompanied by a decrease in vessel density and a decrease in the circularity index of the foveal avascular zone as a result of regression of the parafoveal capillary networks. OCTA allowed visualization of morphological changes at the microcirculatory level in the form of blunt ends of capillaries, their increased tortuosity and the presence of local areas of decreased perfusion. The severity of retinal microvascular changes varied depending on the stage of CKD and was not associated with either age or the presence of diabetes mellitus. Assessment of the retinal microvasculature can help with monitoring of microvascular lesions, early prediction of the risk of development and progression of decreased renal function, as well as allow avoiding aggressive diagnostic biopsy.


Assuntos
Insuficiência Renal Crônica , Tomografia de Coerência Óptica , Angiografia , Angiofluoresceinografia , Humanos , Microcirculação , Insuficiência Renal Crônica/diagnóstico , Insuficiência Renal Crônica/diagnóstico por imagem , Retina/diagnóstico por imagem , Vasos Retinianos/diagnóstico por imagem
9.
BMC Ophthalmol ; 21(1): 254, 2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34103021

RESUMO

BACKGROUND: To quantify and compare retinal microvascular features using optical coherence tomography angiography (OCTA) in constant (XT) and intermittent exotropia (IXT). METHODS: An observational cross-sectional study was conducted from September 2020 to November 2020 at the Affiliated Eye Hospital of Wenzhou Medical University. OCTA examination was performed to evaluate the macular perfusion density of the deep capillary plexus (DCP), superficial capillary plexus (SCP), and foveal avascular zone (FAZ) parameters in XT and IXT patients, and in age-matched controls. The study parameters were analyzed. RESULTS: A total of 76 participants, including 16 (21%) XT patients, 24 (32%) IXT patients, and 36 (47%) controls, were recruited. The exodeviation angle was 39.06 ± 10.38 prism degrees (PD) at near and 43.00 ± 9.74 PD at distance in the XT group, and 27.13 ± 18.28 PD at near and 31.04 ± 18.82 PD at distance in the IXT group. The macular perfusion density of the DCP in 6 × 6-mm scans and the SCP in 3 × 3-mm scans were lower in the deviating eyes than in the fixating eyes of XT patients (p < 0.001, p = 0.032, respectively). The macular perfusion density of the DCP in the deviating eyes of XT and IXT patients was significantly lower than that of the controls. There was no significant difference in the FAZ parameters among the groups. CONCLUSIONS: In XT patients, OCTA revealed lower macular perfusion density in deviating eyes than in fixating eyes and control eyes. IXT patients showed no difference between the two eyes, but the macular perfusion density of the DCP was lower than that of the controls.


Assuntos
Exotropia , Estudos Transversais , Exotropia/diagnóstico por imagem , Angiofluoresceinografia , Fóvea Central , Humanos , Perfusão , Vasos Retinianos/diagnóstico por imagem , Tomografia de Coerência Óptica , Acuidade Visual
10.
Sensors (Basel) ; 21(11)2021 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-34073541

RESUMO

Diabetic retinopathy (DR) is a disease resulting from diabetes complications, causing non-reversible damage to retina blood vessels. DR is a leading cause of blindness if not detected early. The currently available DR treatments are limited to stopping or delaying the deterioration of sight, highlighting the importance of regular scanning using high-efficiency computer-based systems to diagnose cases early. The current work presented fully automatic diagnosis systems that exceed manual techniques to avoid misdiagnosis, reducing time, effort and cost. The proposed system classifies DR images into five stages-no-DR, mild, moderate, severe and proliferative DR-as well as localizing the affected lesions on retain surface. The system comprises two deep learning-based models. The first model (CNN512) used the whole image as an input to the CNN model to classify it into one of the five DR stages. It achieved an accuracy of 88.6% and 84.1% on the DDR and the APTOS Kaggle 2019 public datasets, respectively, compared to the state-of-the-art results. Simultaneously, the second model used an adopted YOLOv3 model to detect and localize the DR lesions, achieving a 0.216 mAP in lesion localization on the DDR dataset, which improves the current state-of-the-art results. Finally, both of the proposed structures, CNN512 and YOLOv3, were fused to classify DR images and localize DR lesions, obtaining an accuracy of 89% with 89% sensitivity, 97.3 specificity and that exceeds the current state-of-the-art results.


Assuntos
Aprendizado Profundo , Diabetes Mellitus , Retinopatia Diabética , Retinopatia Diabética/diagnóstico por imagem , Fundo de Olho , Humanos , Vasos Retinianos/diagnóstico por imagem
11.
Toxicon ; 198: 54-63, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-33961847

RESUMO

In this study, the early retinal and optic nerve blood flows of patients exposed to Viper bite were evaluated with non-invasive optical coherence tomography angiography (OCTA) and compared with healthy controls. The retinal and optic disc OCTA data of 31 victims of viper bite (group S) without systemic envenomation clinical symptoms and 31 healthy controls (group C) were compared. Only patients with early signs of envenomation were included in the study. Optical coherence tomography angiographies were performed with RTVue XR Avanti with AngioVue software. Vascular densities in the whole image, foveal, parafoveal regions at the superficial and the deep capillary plexus segments were acquired and statistically analyzed. The flow area parameters were measured in the superficial retinal capillary plexus, deep retinal capillary plexus, outer retinal capillary plexus, and choriocapillaris layers of the macula in 1-mm and 3-mm diameter areas. The peripapillary flow areas were measured for the optic nerve head, vitreous, radial peripapillary capillary (RPC), and choroid in a 4.50-mm diameter area. Foveal and parafoveal thicknesses were also measured and compared. The average hospital admission time of the patients in group S was 1.24 ± 0.75 (0.50-3.00) hours. Age (p = 0.103) and gender (p = 0.714) were similar in both groups. Superficial (p = 0.010), deep flow areas (p = 0.034), and superficial parafoveal vascular density (p = 0.001) were significantly reduced in group S compared to group C. The outer retinal flow area (p < 0.001) increased significantly in group S. Nerve head flow area (p = 0.035), one of the optic disc flow areas, was found to be decreased in group S. Notably, foveal (p < 0.001) and parafoveal (p = 0.003) thicknesses and superficial (p = 0.001) and deep (p < 0.001) foveal vascular densities were greater in group S. Compared to group C, the superficial (p = 0.009) and deep (p = 0.009) foveal flow areas in the central foveal area with a diameter of 1 mm increased significantly in group S. Viper venom may cause blood flow changes in the retina and optic disc and an increase in retinal thickness in the early period although there are no signs of systemic envenomation.


Assuntos
Disco Óptico , Tomografia de Coerência Óptica , Angiofluoresceinografia , Humanos , Retina/diagnóstico por imagem , Vasos Retinianos/diagnóstico por imagem
12.
BMC Ophthalmol ; 21(1): 209, 2021 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-33975575

RESUMO

BACKGROUND: One of the major side effects of Hydroxychloroquine (HCQ) is retinopathy. The aim of this study was to evaluate the Optical coherence tomography angiography (OCTA) parameters in a group of patients who have Hydroxychloroquine-induced retinopathy based on Multifocal electroretinography (mfERG) with a group who do not have retinopathy. METHOD: This is a Cross-Sectional Study. In this study, patients with Rheumatoid arthritis (RA) or Systemic lupus erythematosus (SLE) who had been taking Hydroxychloroquine for at least 7 years were included. MfERG and OCTA imaging were performed for all patients. Patients were divided into Normal mfERG and Abnormal mfERG groups based on mfERG results. OCTA parameters were studied in these two groups. RESULT: Sixty-one patients (61 eyes) were included. Forty-one patients had SLE and 20 patients had RA. Forty patients (66.7%) had Abnormal mfERG. The mean vascular density (VD) in Superficial capillary plexus (SCP) layer was not significantly different between Normal mfERG and Abnormal mfERG groups (P-Value> 0.05). Mean VD in SCP layer was not significantly different between Normal mfERG and Abnormal mfERG groups (P-Value> 0.05). In RA subgroup, mean VD in SCP layer in PeriFovea region in Abnormal mfERG group was significantly lower than normal group (P-Value < 0.05). Mean VD in deep capillary plexus (DCP) layer in Whole Image, Superior Hemi, Inferior Hemi, PeriFovea area in Abnormal mfERG group was significantly lower than normal group (P-Value < 0.05). This discrepancy was also observed in the RA subgroup but not in the SLE subgroup. The mean of none of the parameters of foveal avascular zone (FAZ) (mm2), Flow Area of Outer Retina (mm2) and Flow Area of Choriocapillaris (mm2) were not statistically significant between the groups Abnormal mfERG and Normal mfERG. (p-value> 0.05). CONCLUSION: VD in the DCP layer decreased in abnormal mfERG patients compared to patients with normal mfERG. But it seems that VD in SCP layer, FAZ Area and Flow Area are similar in both groups. OCTA may be used as a non-invasive tool in the diagnosis of early stages of HCQ-induced retinopathy, especially in RA patients, but further studies are needed.


Assuntos
Hidroxicloroquina , Tomografia de Coerência Óptica , Estudos Transversais , Angiofluoresceinografia , Humanos , Hidroxicloroquina/efeitos adversos , Vasos Retinianos/diagnóstico por imagem
13.
Transl Vis Sci Technol ; 10(2): 5, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-34003890

RESUMO

Similar to other organs, the retina relies on tightly regulated perfusion and oxygenation. Previous studies have demonstrated that retinal blood flow is affected in a variety of eye and systemic diseases, including diabetic retinopathy, age-related macular degeneration, and glaucoma. Although measurement of peripheral oxygen saturation has become a standard clinical measurement through the development of pulse oximetry, developing a noninvasive technique to measure retinal oxygen saturation has proven challenging, and retinal oximetry technology currently remains inadequate for reliable clinical use. Here, we review current strategies and approaches, as well as several newer technologies in development, and discuss the future of retinal oximetry.


Assuntos
Retinopatia Diabética , Vasos Retinianos , Humanos , Oximetria , Oxigênio , Retina/diagnóstico por imagem , Vasos Retinianos/diagnóstico por imagem
14.
Transl Vis Sci Technol ; 10(2): 6, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-34003893

RESUMO

Purpose: To use high-resolution histology to define the associations between microaneurysms, capillary diameter and capillary density alterations in diabetic retinopathy (DR). Methods: Quantitative comparisons of microaneurysm number, capillary density and capillary diameter were performed between eight human donor eyes with nonproliferative DR and six age- and eccentricity-matched normal donor eyes after retinal vascular perfusion labelling. The parafovea, 3-mm, 6-mm, and 9-mm retinal eccentricities were analyzed and associations between microvascular alterations defined. Results: Mean capillary density was reduced in all retina regions in the DR group (P = 0.013). Microaneurysms occurred in all retina regions in the DR group, but the association between decreased capillary density and microaneurysm number was only significant in the 3-mm (P = 0.040) and 6-mm (P = 0.007) eccentricities. The mean capillary diameter of the DR group (8.9 ± 0.53 µm) was greater than the control group (7.60 ± 0.40 µm; P = 0.033). There was no association between capillary diameter increase and capillary density decrease (P = 0.257) and capillary diameter increase and microaneurysm number (P = 0.147) in the DR group. Within the parafovea of the DR group, capillary density was significantly reduced, and capillary diameter was significantly increased in the deep capillary plexus compared with the superficial and intermediate plexuses (all P < 0.05). Conclusions: In DR, capillary density reduction occurs across multiple retina eccentricities with a predilection for the deep capillary plexus. The association between microaneurysm number and capillary density is specific to retina eccentricity. Capillary diameter increase may be an early biomarker of DR. These findings may refine the application of optical coherence tomography angiography techniques for the management of DR.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Microaneurisma , Angiofluoresceinografia , Humanos , Microaneurisma/diagnóstico por imagem , Microscopia Confocal , Vasos Retinianos/diagnóstico por imagem , Tomografia de Coerência Óptica
15.
Transl Vis Sci Technol ; 10(2): 9, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-34003897

RESUMO

Purpose: To investigate the characteristics of the retinal periarterial capillary-free zone (paCFZ) with wide-field swept-source optical coherence tomography angiography (SS-OCTA) in eyes with branch retinal vein occlusion (BRVO). Methods: Seventy treatment-naïve eyes with BRVO and 35 healthy eyes were included. The paCFZ areas, artery calibers, and areas of the major arteries in the unaffected quadrants of BRVO eyes were measured in 12 × 12-mm SS-OCTA images and compared with those of the contralateral eyes and healthy eyes. Other multimodal imaging data were collected. Results: There were no significant differences in the unaffected artery caliber or area among the three groups (all P > 0.05). The unaffected paCFZ areas and the ratios of the unaffected paCFZ area to the counterpart artery area (paCFZ/artery area) of the major arteries were significantly larger than those in the contralateral or healthy eyes (all P < 0.05). Subgroup analysis revealed that the paCFZ/artery area value differed significantly between ischemic and nonischemic BRVO eyes (P < 0.01). The paCFZ/artery area value was positively correlated with logMAR best-corrected visual acuity, symptom duration, central macular thickness, and retinal nonperfusion area in BRVO. Conclusions: Quantitative SS-OCTA measurements confirmed enlarged paCFZs along the unaffected major retinal arteries in BRVO eyes. The paCFZ parameters were correlated with symptom duration, retinal ischemia, and visual function. Translational Relevance: Retinal periarterial capillary-free zones in BRVO can be non-invasively measured by SS-OCTA, assisting in clinically identifying retinal ischemia and evaluating visual function.


Assuntos
Oclusão da Veia Retiniana , Angiofluoresceinografia , Humanos , Oclusão da Veia Retiniana/diagnóstico por imagem , Vasos Retinianos/diagnóstico por imagem , Estudos Retrospectivos , Tomografia de Coerência Óptica , Acuidade Visual
16.
Transl Vis Sci Technol ; 10(2): 20, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-34003905

RESUMO

Purpose: To develop a deep learning-based method to achieve vessel segmentation and measurement on fundus images, and explore the quantitative relationships between retinal vascular characteristics and the clinical indicators of renal function. Methods: We recruited patients with type 2 diabetes mellitus with different stages of diabetic retinopathy (DR), collecting their fundus photographs and results of renal function tests. A deep learning framework for retinal vessel segmentation and measurement was developed. The correlation between the renal function indicators and the severity of DR were explored, then the correlation coefficients between indicators of renal function and retinal vascular characteristics were analyzed. Results: We included 418 patients (eyes) with type 2 diabetes mellitus. The albumin to creatinine ratio, blood uric acid, blood creatinine, blood albumin, and estimated glomerular filtration rate were significantly correlated with the progression of DR (P < 0.05); no correlation existed in other metrics (P > 0.05). The fractal dimension was found to significantly correlate with most of the clinical parameters of renal function (P < 0.05). Conclusions: The albumin to creatinine ratio, blood uric acid, blood creatinine, blood albumin, and estimated glomerular filtration rate have significant correlation with the progression of moderate to proliferative DR. Through deep learning-based vessel segmentation and measurement, the fractal dimension was found to significantly correlate with most clinical parameters of renal function. Translational Relevance: Deep learning-based vessel segmentation and measurement on color fundus photographs could explore the relationships between retinal characteristics and renal function, facilitating earlier detection and intervention of type 2 diabetes mellitus complications.


Assuntos
Diabetes Mellitus Tipo 2 , Retinopatia Diabética , Diabetes Mellitus Tipo 2/complicações , Retinopatia Diabética/diagnóstico , Fundo de Olho , Taxa de Filtração Glomerular , Humanos , Vasos Retinianos/diagnóstico por imagem
17.
Transl Vis Sci Technol ; 10(2): 40, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-34003925

RESUMO

Purpose: To characterize changes in retinal perfusion during pregnancy and the postpartum period using optical coherence tomography angiography (OCTA). Methods: A nonmydriatic OCTA camera was used to image healthy women who were pregnant or in the postpartum period along with nonpregnant controls. Perfusion density (PD) and vessel length density (VLD) in the superficial capillary plexus (SCP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP) were evaluated. Results: A total of 16, 15, and 13 eyes from nonpregnant, pregnant, and healthy postpartum subjects, respectively, were evaluated. When compared to controls, there were significant increases in ICP PD during the second and third trimester of pregnancy, along with significant decreases in both PD and VLD in SCP, ICP, and DCP up to 14 weeks postpartum. Conclusions: During pregnancy, vascular changes consistent with retinal vasodilation were noted in the ICP. During the postpartum period, changes in retinal vasculature suggest relative vasoconstriction involving all three layers when compared to both the pregnant and nonpregnant states. Translational Relevance: Detecting postpartum changes in retinal vasculature could offer important insights into postpartum physiology throughout the body.


Assuntos
Tomografia de Coerência Óptica , Vasoconstrição , Feminino , Angiofluoresceinografia , Humanos , Período Pós-Parto , Gravidez , Vasos Retinianos/diagnóstico por imagem
18.
Transl Vis Sci Technol ; 10(3): 2, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-34003936

RESUMO

Purpose: To explore optical coherence tomography angiography (OCTA) quality and associated factors in multicenter clinical studies. Methods: OCTA scans were obtained from participants with diabetic retinopathy from three DRCR Retina Network clinical studies using the Optovue AngioVue and ZEISS AngioPlex. Macular (3 × 3 mm and 6 × 6 mm) and optic nerve scans were captured. Quality was assessed by the Casey Reading Center. Scans were considered "poor" if the signal strength index (SSI) was less than 55 (AngioVue) or 7 (AngioPlex) or if excess motion, media opacities, beam defocus, incorrect axial position, or other artifacts were present. Results: Included were 7539 scans from 787 eyes (461 participants). Sixty-one percent of scans were considered "good" (n = 4630). Of the 3 × 3-mm (n = 2294), 6 × 6-mm (n = 2705), and optic nerve scans (n = 2540), 62%, 63%, and 59%, respectively, were good. Differences in percentage of good scans by machine were not identified (61% of 6216 for the AngioVue and 63% of 1323 for the AngioPlex). The primary reason for poor scans was low SSI for the AngioVue (67%) and excess motion for the AngioPlex (47%). Good scans were associated with younger age (60 ± 12 years vs. 65 ± 11 years; P < 0.001), male gender (64% of males had good scans vs. 57% female; P = 0.007), and better visual acuity (ETDRS letter score 86.5 ± 6.4 [approximate Snellen equivalent 20/20] vs. 81.6 ± 9.7 [approximate Snellen equivalent 20/25]; P < 0.001). Conclusions: Scan quality or analysis must be improved for OCTA metrics to be used as outcomes in future research. Translational Relevance: Clinicians and researchers should be aware that poor SSI and artifacts are common issues for OCTA images.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Idoso , Retinopatia Diabética/diagnóstico , Feminino , Angiofluoresceinografia , Humanos , Masculino , Pessoa de Meia-Idade , Vasos Retinianos/diagnóstico por imagem , Tomografia de Coerência Óptica , Acuidade Visual
19.
Transl Vis Sci Technol ; 10(3): 23, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-34003956

RESUMO

Purpose: To determine possible impacts on retinal microvasculature in healthy young adults during exercise with a face mask, using optical coherence tomography angiography (OCTA). Methods: Twenty-three healthy participants (23 eyes, 17 women and 6 men) performed the incremental continuous running test (ICRT) with different masks. OCTA of the macula and optic nerve head were performed before and after ICRT to detect changes in retinal vessel density (VD). All participants were in groups A, B, and C (before ICRT) and groups A', B', and C' (after ICRT), which comprised data from volunteers without a mask, with a surgical mask, and with an N95 mask, respectively. Results: Before ICRT, group C showed significantly reduced VD in the superficial plexus (SP), except foveal VD, compared with group A (P < 0.05). After ICRT, groups B' and C' showed significantly shorter maximum running time, lower oxygen saturation, and lower perifoveal VD of SP compared with group A' (P < 0.05). Conclusions: Use of an N95 mask reduced VD in SP even under quiescent conditions, which might have clinical implications for protecting healthy workers and indoor manual labor workers from potential risks of retinal damage due to long-term mask use. Moreover, mask use while exercising might lead to attenuated exercise ability and lower VD in SP, which should be investigated in additional studies. Translational Relevance: Retina vascular perfusion dynamics could be monitored in vivo by OCTA, which would be valuable to study physiologic retinal blood flow redistribution and potential impacts on retinal vascular perfusion during exercise with face masks.


Assuntos
Máscaras , Vasos Retinianos , Feminino , Angiofluoresceinografia , Humanos , Masculino , Perfusão , Retina/diagnóstico por imagem , Vasos Retinianos/diagnóstico por imagem , Adulto Jovem
20.
Transl Vis Sci Technol ; 10(4): 31, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-34004010

RESUMO

Purpose: To establish a custom-built, high-speed 90 frame-per-second laser-scanning confocal microscope for real-time in vivo retinal imaging of individual flowing red blood cells (RBCs) in retinal vasculature of live mouse model. Methods: Fluorescently labeled RBCs were injected into mice of different ages (3 to 62 weeks old). Anti-CD31 antibody conjugated with Alexa Fluor 647 was injected to visualize retinal endothelial cells (ECs). Longitudinal and cross-sectional intravital retinal imaging of flowing RBCs and ECs was performed in two strains (C57BL/6 and Balb/c) by using the custom-built confocal microscope. Results: Simultaneous tracking of the routes of many fluorescently labeled individual RBCs flowing from a large artery and vein to a single capillary in the retina of live mice was achieved, which enabled in vivo measurement of retinal RBC flow velocities in each vessel type in growing mice from 3 to 62 weeks after birth. Average RBC flow velocities were gradually increased during growing from 3 to 14 weeks by more than two times. Then the average RBC flow velocity was maintained at about 20 mm/s in artery and 16 mm/s in vein until 62 weeks. Conclusions: Our study successfully established a custom-built high-speed 90-Hz retinal confocal microscope for measuring RBC flow velocity at the single cell level. It could be a useful tool to investigate the pathophysiology of various retinal diseases associated with blood flow impairment. Translational Relevance: This technological method could be a valuable assessment tool to help the development of novel therapeutics for retinal diseases.


Assuntos
Células Endoteliais , Vasos Retinianos , Animais , Estudos Transversais , Eritrócitos , Microscopia Intravital , Camundongos , Camundongos Endogâmicos C57BL , Vasos Retinianos/diagnóstico por imagem
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