Optical coherence tomography angiography: a non-invasive tool to image end-arterial system

Optical Coherence Tomography and Optical Coherence Tomography Angiography in Neglected Diseases

A group of self-limiting and frequently neglected diseases exist in the literature like Rickettsial disease, Malaria, Dengue fever, Chikungunya, West Nile virus infection, Rift Valley fever, Bartonellosis, or Lyme disease which are poorly understood due to lack of proper diagnostic testing. Currently, multimodal imaging has become a critical modality in the diagnosis and management of ocular diseases. Optical coherence tomography (OCT) is one such remarkable imaging modality in the field of ophthalmology providing high-resolution, cross-sectional images of the retina and choroid with the recent advances such as enhanced depth imaging and swept source OCT. Additionally, OCT angiography (OCTA) has further revolutionised dynamic imaging of retinal and choroidal vasculature non-invasively. This review article highlights the OCT and OCTA biomarkers in the diagnosis and prognosis of the aforementioned neglected diseases.

Microvascular changes after pars plana vitrectomy for rhegmatogenous retinal detachment repair: A comparative study based on gas tamponade agent

PURPOSE

The purpose of this study was to investigate the effect of gas tamponade on microvascular changes in patients with rhegmatogenous retinal detachment (RRD), who underwent pars plana vitrectomy (PPV), using optical coherence tomography angiography (OCTA).

METHODS

Participants in this study were 48 patients with RRD, who were treated with PPV and gas tamponade without internal limiting membrane peeling. All participants underwent slit-lamp examination, fundoscopy, spectral domain-optical coherence tomography and optical coherence tomography angiography at month 6 postoperatively. The fellow untreated eyes were also examined and served as the control data.

RESULTS

A statistically significant enlargement in the foveal avascular zone (FAZ) in both the superficial (p = 0.002) and the deep capillary plexus (p = 0.01) was noticed 6 months postoperatively in patients with RRD treated with PPV compared to the fellow eyes. The foveal avascular zone perimeter was increased in the operated eyes in the deep capillary plexus (p = 0.0003) and the foveal avascular zone circularity was decreased in both the superficial (p = 0.045) and the deep capillary plexus (p < 0.001) compared to the fellow eyes. The vessel density was not significantly different between the operated and the fellow eyes in the superficial and the deep capillary plexus. The vessel density and the foveal avascular zone parameters were comparable between the C3F8 and SF6 groups.

CONCLUSION

Specific microvascular indices as measured by OCTA were statistically different between the operated and the fellow eyes in the superficial and deep capillary plexus. C3F8 and SF6 as gas tamponades did not seem to differ in their impact on the microvascular parameters.

Optical coherence tomography angiography as a potential tool in differential diagnosis of multiple sclerosis and rheumatic disorders with central nervous system involvement

PURPOSE

The aim of this study is to analyse whether optical coherence tomography angiography (angio-OCT, OCTA) measurements can be a useful tool to differentiate central nervous system (CNS) involvement in rheumatic disorders (RD) from multiple sclerosis (MS).

METHODS

A total of 85 patients- 41 with MS, 21 with RD with CNS involvement and 23 healthy controls were included in the study. All individuals underwent OCTA and the following parameters were measured in each eye separately: average foveal and parafoveal vessel density (VD), average foveal and parafoveal vessel length (VL) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), as well as area, perimeter, and circularity of the foveal avascular zone.

RESULTS

OCTA showed a VD reduction in the foveal region of the SCP in eyes of RD patients when compared to MS patients (21.96 ± 3.39 vs.23.88 ± 3.05 (p = 0.003)). There have been no significant differences in any of the assessed parameters that is average VD and total average VL in the foveal area of the SCP as well as of the DCP in the general population comprising healthy controls, MS and RD groups (p > 0.05 for all).

CONCLUSIONS

Our results suggest that an OCTA finding of decreased VD in the foveal region of the SCP may be considered as a potentially useful biomarker of RD in comparison with MS patients.

Ocular endothelial dysfunction in pediatric inflammatory bowel disease

OBJECTIVES

To assess ocular microvasculature changes using optical coherence tomography angiography (OCTA) in pediatric patients with inflammatory bowel disease (IBD).

METHODS

Patients (aged 6-18 years) with IBD were recruited between September 2021 and May 2023. All eligible participants underwent comprehensive clinical assessment and laboratory investigation. Patients with functional gastrointestinal disorders served as the controls. This study assessed specific IBD phenotypes, disease duration, clinical and endoscopic activity indices, laboratory markers, and medication histories. OCTA was utilized to evaluate ocular microvasculature changes in both groups.

RESULTS

A total of 63 children (mean age 12.9 ± 3.3 years) were enrolled, comprising 38 in the IBD group (16 ulcerative colitis, 22 Crohn's disease, and 25 in the control group). Most patients in the IBD group were in remission or had mild-to-moderate disease activity at enrollment. Analysis of the OCTA results revealed significant differences in the choroidal luminal area and total choroidal area between the IBD and control groups.

CONCLUSIONS

The study identified distinct ocular microvasculature changes in pediatric IBD patients through OCTA, suggestive of potential systemic endothelial dysfunction. These findings underscore the utility of OCTA in evaluating microvascular alterations associated with pediatric IBD, offering insights into potential systemic complications linked to inflammation in IBD patients.

Optometrists' attitudes toward using OCT angiography lag behind other retinal imaging types

PURPOSE

While optometrists' attitudes toward established retinal imaging types are generally positive, they are unknown for optical coherence tomography angiography (OCTA). We performed a cross-sectional survey to estimate attitudes toward OCTA and identify clinician and/or practice characteristics that influence them.

METHODS

A paper-based survey was mailed to 252 randomly selected optometrists in Australia. Five-point Likert-scale items from a previous survey assessing attitudes toward new technology were included to probe respondent characteristics and attitudes toward retinal imaging. Performance expectancy attitudes toward OCTA were elicited by the statement 'I believe OCTA is useful in daily practice'. Mean scores out of five (mean [SD]) were rounded and mapped to appropriate descriptive statements.

RESULTS

The response rate was 47% (118/252). The mean (SD) age of respondents was 44.0 (13.8) years and 50.8% (60/118) were female. Optometrists had 19.9 (14.0) years of clinical experience and 66.9% (79/118) worked at independent practices. In total, 8.5% (10/118) of respondents used OCTA to provide clinical care. Optometrists agreed that optical coherence tomography (OCT), colour fundus imaging, ultra-wide field imaging and fundus autofluorescence (mean scores 3.6-4.7 out of 5) were useful in daily practice but felt neutral about whether OCTA was useful (3.4 [0.8]). Optometrists believed that OCTA was less enjoyable to use (p < 0.0001), less endorsed by peers (p < 0.0001) and felt less confident that they had the knowledge to interpret OCTA (p < 0.0001) compared to other retinal imaging types.

CONCLUSIONS

Optometrists are undecided on whether OCTA is useful in daily practice and had lower expectations that using OCTA would confer job performance benefits compared to other retinal imaging types. Further work is needed to advocate the benefits of using OCTA across the profession.

Influence of scan direction on subfoveal choroidal vascularity index using optical coherence tomography

We investigated the influence of scan direction on subfoveal choroidal vascularity index (CVI) measurements using spectral-domain optical coherence tomography (SD-OCT) in young healthy subjects. Seventy-eight eyes of 41 healthy volunteers were included. Choroidal structures were obtained using SD-OCT with enhanced depth imaging (EDI) through radial scans at the center of the macula. The subfoveal choroidal images in the horizontal (0°), 45°, vertical (90°) and − 45° directions were recorded and CVIs were analyzed according to their respective directions using image binarization. Additionally, subfoveal choroidal thickness (SFCT), and axial eye length were measured. The SFCT and subfoveal CVI showed a negative correlation but were only significant for the 45° scan (Pearson’s r = − 0.262, P = 0.021). The axial eye length and subfoveal CVI had no significant correlation in any direction (all P > 0.05). In the Bland–Altman plot, the subfoveal CVI measurement showed high agreement among the four scan directions. When the SFCT was ≥ 300 µm, there was no difference in the measured values of the subfoveal CVI among the four scan directions; however, when the SFCT was < 300 µm, there was a significant difference in subfoveal CVI among the scan directions (one-way analysis of variance, F = 4.685, P = 0.004). In subfoveal CVI measurement, it is considered that the horizontal (0°) scan can represent the vertical (90°) or oblique (45°, − 45°) scans. However, when the SFCT is thinner, the subfoveal CVI in each direction of radial scan may vary significantly. Hence, caution is required in the interpretation.

Early Structural and Vascular Changes after Within-24 Hours Vitrectomy for Recent Onset Rhegmatogenous Retinal Detachment Treatment: A Pilot Study Comparing Bisected Macula and Not Bisected Macula

Background: In this study we aimed at investigating macular perfusion/anatomical changes in eyes with early onset rhegmatogenous retinal detachment (RRD) after prompt surgery within 24 hours, comparing a bisected macula and not bisected macula RRD. Methods: In this prospective observational study, 14 eyes of 14 patients who underwent within-24 hours vitreoretinal surgery for early onset RRD were enrolled. Patients were further divided into two subgroups: the not bisected macula group (NBM group) and the bisected macula group (BM group). At baseline and 3-month follow up, macular architecture and vessel analysis were assessed using optical coherence tomography angiography (OCTA) imaging. In detail, quantitative and qualitative analyses of the macular area were performed to quantify topographical retinal perfusion changes after surgery, calculating the foveal avascular zone (FAZ), vessel density (VD) and vessel length density (VLD) at the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Results: Most cases (43%) were superotemporal RRD. Primary retinal reattachment was obtained in all cases, without recurrences within 3-month follow up. After surgery, a significant FAZ enlargement was observed at both the SCP and DCP level (p < 0.001; p < 0.05), with a significant effect of time noted between the two time points in the NBM and BM subanalysis (F = 3.68; p < 0.017). An excellent functional outcome was maintained for the whole follow-up. On the other hand, after surgery, perfusion parameters did not change significantly apart from the vessel density of the inferior macular sector at the DCP level (p = 0.03). Conclusions: Our findings suggest that the macular perfusion of eyes with RRD is still preserved if the surgery is performed really promptly, thus highlighting the great importance of a correct timing for surgery. OCTA analysis allows for a better understanding of the pathophysiological mechanisms underneath early vascular microarchitecture modifications of the posterior pole in retinal detachment, differentiating the two types of RRD not completely involving the fovea (BM and NBM).

Associations Between the Macular Microvasculatures and Subclinical Atherosclerosis in Patients With Type 2 Diabetes: An Optical Coherence Tomography Angiography Study

Objective

To investigate the associations between the macular microvasculature assessed by optical coherence tomography angiography (OCTA) and subclinical atherosclerosis in patients with type 2 diabetes.

Methods

We included patients with type 2 diabetes who received comprehensive medical and ophthalmic evaluations, such as carotid ultrasonography and OCTA at a hospital-based diabetic clinic in a consecutive manner. Among them, 254 eyes with neither diabetic macular edema (DME) nor history of ophthalmic treatment from 254 patients were included. The presence of increased carotid intima-media thickness (IMT) (&gt;1.0 mm) or carotid plaque was defined as subclinical atherosclerosis. OCTA characteristics focused on foveal avascular zone (FAZ) related parameters and parafoveal vessel density (VD) were compared in terms of subclinical atherosclerosis, and risk factors for subclinical atherosclerosis were identified using a multivariate logistic regression analysis.

Results

Subclinical atherosclerosis was observed in 148 patients (58.3%). The subclinical atherosclerosis group were older (p &lt; 0.001), had a greater portion of patients who were men (p = 0.001) and who had hypertension (p = 0.042), had longer diabetes duration (p = 0.014), and lower VD around FAZ (p = 0.010), and parafoveal VD (all p &lt; 0.05). In the multivariate logistic regression analysis, older age (p ≤ 0.001), male sex (p ≤ 0.001), lower VD around FAZ (p = 0.043), lower parafoveal VD of both superficial capillary plexus (SCP) (p = 0.011), and deep capillary plexus (DCP) (p = 0.046) were significant factors for subclinical atherosclerosis.

Conclusion

The decrease in VD around FAZ, and the VD loss in parafoveal area of both SCP and DCP were significantly associated with subclinical atherosclerosis in patients with type 2 diabetes, suggesting that common pathogenic mechanisms might predispose to diabetic micro- and macrovascular complications.

Optical Coherence Tomography Angiography in Diabetic Patients: A Systematic Review

Background: Diabetic retinopathy (DR) is the leading cause of legal blindness in the working population in developed countries. Optical coherence tomography (OCT) angiography (OCTA) has risen as an essential tool in the diagnosis and control of diabetic patients, with and without DR, allowing visualisation of the retinal and choroidal microvasculature, their qualitative and quantitative changes, the progression of vascular disease, quantification of ischaemic areas, and the detection of preclinical changes. The aim of this article is to analyse the current applications of OCTA and provide an updated overview of them in the evaluation of DR. Methods: A systematic literature search was performed in PubMed and Embase, including the keywords “OCTA” OR “OCT angiography” OR “optical coherence tomography angiography” AND “diabetes” OR “diabetes mellitus” OR “diabetic retinopathy” OR “diabetic maculopathy” OR “diabetic macular oedema” OR “diabetic macular ischaemia”. Of the 1456 studies initially identified, 107 studies were screened after duplication, and those articles that did not meet the selection criteria were removed. Finally, after looking for missing data, we included 135 studies in this review. Results: We present the common and distinctive findings in the analysed papers after the literature search including the diagnostic use of OCTA in diabetes mellitus (DM) patients. We describe previous findings in retinal vascularization, including microaneurysms, foveal avascular zone (FAZ) changes in both size and morphology, changes in vascular perfusion, the appearance of retinal microvascular abnormalities or new vessels, and diabetic macular oedema (DME) and the use of deep learning technology applied to this disease. Conclusion: OCTA findings enable the diagnosis and follow-up of DM patients, including those with no detectable lesions with other devices. The evaluation of retinal and choroidal plexuses using OCTA is a fundamental tool for the diagnosis and prognosis of DR.

Optical coherence tomography

During the past decade, noninvasive imaging has emerged as a valuable tool in clinical dermatology and dermatologic research. Optical coherence tomography (OCT) is one such type of noninvasive imaging. OCT uses the principle of interferometry to produce real-time images. A low-power diode laser shines infrared light onto tissues, which reflects back to an optical fiber interferometer. Using time delay and the backscattered light intensity, a two-dimensional image akin to an ultrasound is rendered. We review the history, types, and modalities of OCT, plus the many applications of frequency domain, high definition, and dynamic OCT in practice, including its utility in diagnosis, monitoring, and grading disease severity in a variety of cutaneous conditions.

Differences between Mycobacterium chimaera and tuberculosis Using Ocular Multimodal Imaging: A Systematic Review

Due to their non-specific diagnostic patterns of ocular infection, differential diagnosis between Mycobacterium (M.) chimaera and tuberculosis can be challenging. In both disorders, ocular manifestation can be the first sign of a systemic infection, and a delayed diagnosis might reduce the response to treatment leading to negative outcomes. Thus, it becomes imperative to distinguish chorioretinal lesions associated with M. chimaera, from lesions due to M. tuberculosis and other infectious disorders. To date, multimodal non-invasive imaging modalities that include ultra-wide field fundus photography, fluorescein and indocyanine green angiography, optical coherence tomography and optical coherence tomography angiography, facilitate in vivo examination of retinal and choroidal tissues, enabling early diagnosis, monitoring treatment response, and relapse detection. This approach is crucial to differentiate between active and inactive ocular disease, and guides clinicians in their decisional-tree during the patients’ follow-up. In this review, we summarized and compared the available literature on multimodal imaging data of M. chimaera infection and tuberculosis, emphasizing similarities and differences in imaging patterns between these two entities and highlighting the relevance of multimodal imaging in the management of the infections.

Evaluation of vessel density in disorganization of retinal inner layers after resolved diabetic macular edema using optical coherence tomography angiography

Purpose

To evaluate the retinal vessel density (VD) in the macular region and the foveal avascular zone (FAZ) area using optical coherence tomography angiography (OCTA) in patients with and without disorganization of retinal inner layers (DRILs) after resolution of diabetic macular edema.

Methods

Thirty-seven eyes of 37 DRIL patients (mean age 63 ± 13.97 years), 30 eyes of 30 no DRIL patients and 35 eyes of 35 controls were enrolled in this study. We evaluated the VD in the macular region of superficial capillary plexus (SCP), deep capillary plexus (DCP) and FAZ area.

Results

DRIL and no DRIL groups showed decreased VD in SCP and DCP (p<0.05) and a larger FAZ area (p<0.001) compared to controls. However, DRIL patients revealed a statistically significant reduction in VD of SCP (p = 0.041) and a greater FAZ area (p<0.001) with respect to no DRIL patients. We found a significant negative correlation between the VD of the foveal SCP (r = -0.414, p = 0.011), foveal DCP (r = -0.358, p = 0.025) and best corrected visual acuity (BCVA) in DRIL group. Moreover there was a significant positive correlation between the FAZ area (r = 0.425, p = 0.034) and BCVA. Therefore, in presence of DRILs lower VD values of SCP and DCP and a larger FAZ area correlated with a worse visual acuity. In no DRILs group, there was a significant negative correlation between the VD of the foveal DCP and BCVA.

Conclusion

OCTA highlights the role of retinal vascular ischemia in the pathogenesis of DRILs. This parameter could represent an important functional predictive factor in diabetic patients.

Diabetic Macular Ischemia: Influence of Optical Coherence Tomography Angiography Parameters on Changes in Functional Outcomes Over One Year

Purpose

To prospectively evaluate whether diabetic macular ischemia detected with coherence tomography angiography (OCTA) is associated with change in functional outcomes over a period of one year.

Methods

This is a one-year prospective, observational study that included 56 eyes with varying levels of diabetic retinopathy. All participants underwent best corrected visual acuity evaluation, swept-source OCTA and microperimetry at baseline and repeated at one year. Parafoveal vessel densities (VD) and foveal avascular zone (FAZ) areas were generated from OCTA in the superficial and deep vascular plexuses. The influence of baseline and change in OCTA parameters on change in visual acuity and retinal sensitivity over one year was evaluated.

Results

Over the one-year follow-up period, 16% (9) of eyes had at least one line worsening in BCVA and 7% (4) of eyes had at least 5% decrease in retinal sensitivity compared to baseline. Diabetic retinopathy progressed in 12.5%. Mean superficial vascular plexus (SVP) FAZ area increased (0.32 ± 0.15 to 0.39 ± 0.18 mm2, P = 0.003) and parafoveal VD in deep vascular plexus (DVP) decreased (49.8 ± 3.7% to 48.8 ± 2.9%, P = 0.040) at one year compared to baseline. In the multivariate regression analysis, larger baseline DVP FAZ area was associated with worsening of BCVA over one year (β = 0.16 logMAR per mm2, 95% CI 0.02 to 0.31, P = 0.032). In addition, larger decreases in SVP VD (β = -4.18 db per 10% decrease, 95% CI -6.55 to -1.80, P = 0.002) was associated with worsening of retinal sensitivity over one year.

Conclusions

Progression of parafoveal microvasculature changes over one year can be detected using OCTA. Larger baseline DVP FAZ area on OCTA is predictive of worsening in visual outcomes, and larger decreases in SVP VD were associated with worsening of retinal sensitivity over a course of one year in diabetic individuals.

Advances and potential new developments in imaging techniques for posterior uveitis. Part 1: noninvasive imaging methods

The aim of this review was to identify the imaging methods at our disposal to optimally manage posterior uveitis at the present time. The focus was put on methods that have become available since the 1990s, some 30 years after fluorescein angiography had revolutionized imaging of posterior uveitis in particular imaging of the retinal vascular structures in the 1960s. We have focussed our review on precise imaging methods that have been standardized and validated and can be used universally thanks to commercially produced and available instruments for the diagnosis and follow-up of posterior uveitis. The first part of this imaging review will deal with noninvasive imaging methods, focusing on fundus autofluorescence and optical coherence tomography as well as recent developments in imaging of the posterior segment.

FRACTAL DIMENSION AND OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FEATURES OF THE CENTRAL MACULA AFTER REPAIR OF RHEGMATOGENOUS RETINAL DETACHMENTS

PURPOSE

Patients with macula-off rhegmatogenous retinal detachments (RRDs) may have suboptimal visual recovery, despite successful reattachment due to various reasons. This study was performed to evaluate the retinal microvasculature in subjects undergoing surgery for RRD using optical coherence tomography angiography.

METHODS

In this case-control study, the analysis of optical coherence tomography angiography findings of 19 eyes of 19 patients (15 men) who underwent RRD surgery at a tertiary institute were compared with 19 eyes of 19 age- and sex-matched healthy subjects with no known ocular disease. 3 × 3-mm optical coherence tomography angiography scans were obtained at 3 months postoperatively and analyzed. Optical coherence tomography angiography images of patients with RRD and control subjects were analyzed for capillary density index and fractal dimensions.

RESULTS

Mean age of the patients was 40.21 years, and the mean age of controls was 43.73 years. Eight eyes underwent scleral buckling alone, and 11 eyes underwent primary vitrectomy with gas tamponade (C3F8 gas) for macula-off RRD. None of the eyes had redetachment during the follow-up at 3 months. Mean capillary density index among patients was 33.28% ± 0.99% and 34.06% ± 2.22% in the superficial and deep retinal plexuses, respectively, compared with 36.11% ± 1.29% and 37.52% ± 1.24% among controls (P < 0.001). The mean fractal dimension was lower among subjects compared with controls (1.46 vs. 1.61 in the superficial plexus, P < 0.001; 1.58 vs. 1.64 in the deep plexus, P < 0.001).

CONCLUSION

Optical coherence tomography angiography demonstrates significant reduction in mean capillary density index and fractal dimension in patients after surgery for RRD in our patients. Thus, reduction in vascular perfusion and branching pattern identified using novel analysis techniques on optical coherence tomography angiography images may provide an insight into the reasons for suboptimal visual gain after RRD surgery.

Imaging in Tubercular Choroiditis: Current Concepts

PURPOSE

Ocular tuberculosis has protean clinical manifestations. Because of its varied clinical presentation, multimodal imaging is very important to characterize the disease activity, presence of inflammation, determining therapeutic response, and detection of complications.

METHODS

Narrative review.

RESULTS

In this review, various imaging modalities employed in the management of ocular tuberculosis including fluorescein angiography (FA), indocyanine green angiography (ICGA), optical coherence tomography (OCT), and optical coherence tomography angiography (OCTA) have been reviewed. Not only do these imaging tools complement each other in providing a comprehensive assessment of the pathology, they also help in gaining valuable insights regarding the evolution of the disease.

CONCLUSIONS

Fundus imaging plays a vital role in the diagnosis and management of patients with posterior uveitis due to tuberculosis. Fundus imaging may have a useful role in defining clinical endpoints for ocular tuberculosis in the future.

Ocular tuberculosis: Where are we today?

Diagnosis and management of ocular tuberculosis (OTB) poses a significant challenge. Mixed ocular tissue involvement and lack of agreement on best practice diagnostic tests together with the global variations in therapeutic management contributed to the existing uncertainties regarding the outcome of the disease. The current review aims to update recent progress on OTB. In particular, the Collaborative Ocular Tuberculosis Study (COTS) group recently standardized a nomenclature system for defining clinical phenotypes, and also proposed consensus guidelines and an algorithmic approach for management of different clinical phenotypes of OTB. Recent developments in experimental research and innovations in molecular diagnostics and imaging technology have provided a new understanding in the pathogenesis and natural history of the disease.

Assessment of macular capillary perfusion in patients with inactive Vogt-Koyanagi-Harada disease: an optical coherence tomography angiography study

PURPOSE

To assess macular capillary perfusion in patients with inactive Vogt-Koyanagi-Harada (VKH) disease by using optical coherence tomography angiography (OCTA).

METHODS

A total of 51 eyes of 51 patients with inactive VKH (group 1, n = 23) and healthy volunteers (group 2, n = 28) underwent detailed eye examination including OCTA (RTVue-XR Avanti) scanning. OCTA images (6 × 6 mm) were assessed for central retinal thickness (CRT), subfoveal choroidal thickness (SFCT), vessel densities (VD) in superficial capillary plexus (SCP) and deep capillary plexus (DCP), choriocapillaris (CC) flow area and vessel flow density (VFD), foveal avascular zone (FAZ) area and acircularity index (AI).

RESULTS

The mean ages of group 1 (13 female, 10 male) and group 2 (15 female, 13 male) were 39.9 ± 11.8 (range, 24-58) and 38.9 ± 8.5 (range, 29-51) years, respectively (p = 0.773). CRT and SFCT were 218.2 ± 39.4 μm and 195.6 ± 28.6 μm in group 1, while 243.5 ± 9.7 μm and 316.7 ± 20.1 μm in group 2, respectively (p < 0.05). VD in SCP and DCP were significantly lower in group 1 (50.6 ± 4.7% vs. 54.3 ± 3.4% and 53.9 ± 3.6% vs. 61.1 ± 2.7% respectively; p < 0.05). FAZ areas were 0.32 ± 0.11 mm² in group 1 and 0.25 ± 0.06 mm² in group 2 (p = 0.046). There was no statistically significant difference between groups regarding AI, CC flow area, and VFD (p > 0.05). There was weak negative correlation between BCVA (logMAR) and parafoveal and perifoveal VD in SCP and DCP of group 1 (p < 0.05).

CONCLUSION

Macular capillary perfusion was significantly reduced both in SCP and DCP in patients with inactive VKH disease.

Comparison of optical coherence tomography angiography results of adult patients with Familial Mediterranean fever and healthy individuals

Purpose

The aim of this study is to assess the macular ultrastructure measuring by optical coherence tomography angiography in adult patients with Familial Mediterranean fever.

Methods

Participants were 62 Familial Mediterranean fever patients and 54 healthy individuals in control group with similar age and sex. The superficial and deep vascular plexus structures covering the central fovea in an area of 6 mm × 6 mm were measured using AngioVue images taken with optical coherence tomography angiography. Vasculature structure, foveal avascular zone, acircularity index of foveal avascular zone (the ratio of the perimeter of foveal avascular zone and the perimeter of a circle with the equal area), and superficial and deep retinal plexus densities were measured.

Results

The inferior deep vascular density was measured: 49.17% ± 8.59% in Familial Mediterranean fever patients, 55.56% ± 5.92% in the control group. The deep inferior-hemi vascular density was measured: 48.59% ± 10.34% in Familial Mediterranean fever patients, 56.54% ± 8.05% in the control group. Deep inferior and deep inferior-hemi vascular density was significantly reduced in Familial Mediterranean fever patients compared with healthy controls (p = 0.04 and p = 0.03, respectively).

Conclusion

The vascular abnormalities in optical coherence tomography angiography show subclinical signs of microangiopathy in Familial Mediterranean fever patients. This observation, which can be obtained only through optical coherence tomography angiography, may be an ocular hallmark for Familial Mediterranean fever disease.

Choroidal vascular changes in internal carotid artery stenosis: a retrospective cohort study in Chinese population

Background

To evaluate choroidal vascularity index (CVI) in eyes with internal carotid artery (ICA) stenosis using binarization tool in enhanced depth images scanned by spectral domain optical coherence tomography.

Methods

A retrospective cohort study was conducted in 142 patients with ICA stenosis, and 20 normal control subjects matched with the age, sex, etc. According to the diagnostic criteria, the participants are divided into a normal control group (20 cases), a mild stenosis group (64 cases), a moderate stenosis group (61 cases), and a severe stenosis group (17 cases). Enhanced depth imaging optical coherence tomography (EDIOCT) was performed to scan macular fovea, which was separated into a luminal area and a stromal area using image binarization. The choroidal vascularity index (CVI) is luminal area divided by total choroidal area.

Results

There was no statistical difference in age or sex among groups. Subfoveal choroidal thickness (SFCT) in the severe stenosis group was significantly lower than that in the normal group (P < 0.05). Moreover, the CVI in moderate stenosis group and severe stenosis group were significantly lower compared with the normal control group (P < 0.001). When CVI = 65.16% was set as the cut-off value, all 162 subjects could be divided into two groups, CVI ≤ 65.16 (n = 83) and CVI > 65.16% (n = 79). The proportions of mild stenosis, moderate stenosis, and severe stenosis in CVI ≤ 65 .16 group and CVI > 65.16% group were statistically significant (P < 0.001).

Conclusion

CVI may be a useful indicator for early diagnosis and monitoring of choroidal vascular changes in ICA stenosis.

Global Assessment of Retinal Arteriolar, Venular and Capillary Microcirculations Using Fundus Photographs and Optical Coherence Tomography Angiography in Diabetic Retinopathy

Retinal arterioles, venules and capillaries are differentially affected in diabetes, and studying vascular alterations may provide information on pathogenesis of diabetic retinopathy (DR). We conducted a cross-sectional study on 49 diabetic patients, who underwent fundus photography and optical coherence tomographic angiography (OCT-A). Fundus photographs were analysed using semi-automated software for arteriolar and venular parameters, including central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE) and fractal dimension (FD). Capillary parameters were measured using OCT-A, including capillary density index (CDI) and capillary FD of superficial (SVP) and deep (DVP) vascular plexuses. Severe DR was defined as severe non-proliferative DR and proliferative DR. We found that eyes with severe DR had narrower CRAE and sparser SVP CDI than eyes without. In logistic regression analysis, capillary parameters were more associated with severe DR than arteriolar or venular parameters. However, combining arteriolar, venular and capillary parameters provided the strongest association with severe DR. In linear regression analysis, eyes with poorer visual acuity had lower CRAE and FD of arterioles, venules, and DVP capillaries. We concluded that the retinal microvasculature is globally affected in severe DR, reflecting widespread microvascular impairment in perfusion. Arteriolar, venular and capillary parameters provide complementary information in assessment of DR.

Optical coherence tomography angiography analysis of the choriocapillary layer in treatment-naïve diabetic eyes

PURPOSE

To evaluate the capillary flow density (CFD) of choriocapillary (CC) microvasculature using optical coherence tomography angiography (OCT-A) in diabetic eyes and the association of CFD and systemic and metabolic factors.

METHODS

Cross-sectional study. This study enrolled 282 eyes of 146 subjects, including 43 healthy control eyes, 56 diabetic eyes without diabetic retinopathy (DR), 43 eyes with mild nonproliferative DR (NPDR), 54 eyes with moderate NPDR, 38 eyes with severe NPDR, and 48 eyes with proliferative DR (PDR). CFD was measured in the CC layer. Clinical data were collected. Multiple linear regression analyses were performed to identify associated clinical variables.

RESULTS

CFD in the CC layer presented a downward trend with DR progression. Comparisons of CFD in the CC layer between adjacent stages of DR revealed significant differences between severe NPDR and PDR using both 3-mm and 6-mm scan patterns (P = 0.003, P = 0.001). CFD in the CC layer in DR with diabetic macular edema (DME) was less than that in DR without DME using both 3-mm and 6-mm scan patterns (P < 0.001, P < 0.001). Coronary artery disease and atherosclerosis in other locations, estimated glomerular filtration rate, and increased HbA1c were associated with CFD in the CC layer using both 3-mm and 6-mm scan patterns (all P values < 0.05).

CONCLUSIONS

OCT-A revealed decreased CFD in the CC layer in the PDR stage and the presence of DME. Diabetic patients with apparently decreased CFD should be assessed carefully under general conditions.

An update on inflammatory choroidal neovascularization: epidemiology, multimodal imaging, and management

Inflammatory choroidal neovascular membranes are challenging to diagnose and manage. A number of uveitic entities may be complicated by the development of choroidal neovascularization leading to a decrease in central visual acuity. In conditions such as punctate inner choroidopathy, development of choroidal neovascularization is extremely common and must be suspected in all cases. On the other hand, in patients with conditions such as serpiginous choroiditis, and multifocal choroiditis, it may be difficult to differentiate between inflammatory choroiditis lesions and choroidal neovascularization. Multimodal imaging analysis, including the recently introduced technology of optical coherence tomography angiography, greatly aid in the diagnosis and management of inflammatory choroidal neovascularization. Management of these neovascular membranes consists of anti-vascular growth factor agents, with or without concomitant anti-inflammatory and/or corticosteroid therapy.

Optical coherence tomography angiography features of bilateral retinopathy associated with Chikungunya fever

A 66-year-old male patient presented with decreased vision in both eyes following episode of Chikungunya fever. Examination revealed bilateral retinal lesions with stippled pigmentary changes at the level of the choriocapillaris, involving the macula in the left eye. The retinopathy consisted of outer retinal disruption and retinochoroidal flow abnormalities detected using with additional imaging, including spectral-domain optical coherence tomography (OCT), autofluorescence, and OCT angiography (OCTA). The index case report describes unique OCTA findings in both eyes of an elderly male secondary to Chikungunya fever. Using the technique of OCTA, insights into the mechanisms of visual damage in viral retinopathies such as Chikungunya fever can be understood.

Multimodal imaging characteristics of quiescent type 1 neovascularization in an eye with angioid streaks

Purpose

To present the multimodal imaging characteristics including optical coherence tomography angiography (OCTA) as well as indocyanine green angiography (ICGA) of quiescent type 1 neovascularization (NV) in an asymptomatic eye with angioid streaks (AS).

Observations

A 67-year-old male patient was admitted to our clinic for routine eye examination. The presence of a quiescent type 1 NV was detected on both ICGA and OCTA in juxtafoveal localization under the retinal pigment epitheliumin the right eye. At the end of the one year of follow-up, the patient was asymptomatic and the type 1 NV was still quiescent.

Conclusions and Importance

In comparison to ICGA, OCTA seems to be an easily repeatable non-invasive imaging tool which enables us early detection and monitoring of type 1 NV lesions even in asymptomatic patients with AS.

Optical coherence tomography angiography features of acute macular neuroretinopathy in dengue fever

A 39-year-old female with dengue fever presented with decreased vision in both eyes. Visual acuity was 20/200 and 20/80 in the right eye (OD) and left eye (OS), respectively. Fundus showed granular, grayish-white lesions in the parafoveal region in OD. Multimodal imaging including optical coherence tomography angiography (OCTA), optical coherence tomography (OCT), and fluorescein angiography (FA) was performed. FA showed late hyperfluorescence with few microaneurysms in OS. OCT showed hyperreflectivity in various layers, suggestive of acute macular neuroretinopathy (AMN). OCTA showed disruption of retinal capillary plexuses. This case shows how OCTA provides newer insights into the pathogenesis of AMN lesions in dengue fever.

Influence of scanning area on choroidal vascularity index measurement using optical coherence tomography

PURPOSE

Recently, choroidal vascularity index (CVI) is proposed as a novel tool to evaluate the choroidal vasculature. In this study, we investigate the impact of scanning area on CVI measurement using spectral-domain optical coherence tomography (SD-OCT).

METHODS

Spectral-domain optical coherence tomography (SD-OCT) using enhanced depth imaging mode was performed in 30 eyes from 15 normal subjects. Three scanning areas were compared: dingle foveal scan; central macular scans [scan passing through central 1000 microns circle on Early Treatment Diabetic Retinopathy Study (ETDRS) grid, inner circle]; and total macular cube scans. Binarization of OCT B-scans and segmentation of the binarized choroid layer were achieved using a previously reported validated automated software. Choroidal vascularity index (CVI) percentage was calculated. Degree of agreement among foveal, central macular and total macular CVI was assessed using intraclass correlation coefficient (ICC) and was plotted using Bland-Altman plot.

RESULTS

The mean CVI in subfoveal, central macular and total macular scans was 49.95 ± 4.84%, 50.00 ± 4.68% and 51.10 ± 4.63%, respectively. Intraclass correlation coefficient (ICC) was more than 0.8 for all three comparisons [subfoveal versus central macular CVI, ICC = 0.92 (95% CI: 0.84-0.96); central macular versus total macular CVI, ICC = 0.90 (95% CI: 0.82-0.96); subfoveal versus total macular CVI, ICC = 0.92 (95% CI: 0.85-0.95)]. No significant differences in variance (all p > 0.05) were noted among CVI measured from the three scanning areas.

CONCLUSION

Choroidal vascularity index (CVI) measurements were highly reproducible using subfoveal, central and total macular scans in healthy individuals. Single foveal scan choroidal vascularity represents total macular choroidal vascularity in healthy population.

Assessment of Vascular Change Using Swept-Source Optical Coherence Tomography Angiography: A New Theory Explains Central Visual Loss in Behcet's Disease

OBJECTIVE

To evaluate retinal vascular structural change in ocular Behcet's using optical coherence tomography angiography (OCTA) and fluorescein angiography (FA).

METHODS

An analytic cross-sectional study of 37 eyes of 21 Behcet's uveitic patients was performed. Foveal retinal thickness (FRT), perifoveal hypoperfusion areas in superficial capillary plexus (SCP), and deep capillary plexus (DCP) were measured with swept-source optical coherence tomography and OCTA. FA images were used for assessing the vascular features and correlation.

RESULTS

Twenty-one patients were enrolled (52.4% males). The average age at onset was 36.7 ± 12.93 years. The median of disease duration was 5 years (1-25). FRT was 118.1 ± 52.35 μm, which correlated with visual acuity (95% CI -60.47, -13.92). Using OCTA, the area of hypoperfusion in SCP (0.47 ± 0.17 mm²) was smaller than that in DCP (1.94 ± 3.87 mm²) (p < 0.001). Superficial to deep capillary plexus nonperfusion (SCP : DCP) ratio was 0.57 ± 0.27 which had the positive coefficient correlation with visual acuity (95% CI -0.644, -0.015).

CONCLUSIONS

OCTA is an alternative noninvasive method to monitor macular ischemia in Behcet. Behcet's uveitis affects DCP more than SCP. Decreasing SCP : DCP ratio and decrease FRT correlates with poor visual acuity. Macular ischemia and DCP loss can be found early and can explain vision loss in Behcet.

Distinguishing features of acute Vogt-Koyanagi-Harada disease and acute central serous chorioretinopathy on optical coherence tomography angiography and en face optical coherence tomography imaging

Background

The aim of this study is to determine the differences in optical coherence tomography angiography (OCTA) features of acute Vogt-Koyanagi-Harada disease (VKH) and acute central serous chorioretinopathy (CSC). Clinical and imaging data of patients with acute CSC and VKH in a tertiary-care institute were analyzed. Multimodal imaging including fluorescein angiography, indocyanine green angiography (ICGA), and enhanced-depth imaging OCT were performed. OCTA images were analyzed for alterations in retinochoroidal microvasculature.

Results

Thirty-four eyes (24 patients; 10 with VKH and 14 with CSC) were included. OCTA en face images showed apparent areas of choriocapillaris flow void due to shadowing effect from overlying subretinal fluid and pigment epithelial detachment in CSC. However, eyes with VKH showed presence of true choriocapillaris flow void on OCTA that corresponded to choriocapillaris ischemia on ICGA.

Conclusions

OCTA is a useful tool to assess choriocapillaris ischemia in VKH and is helpful to differentiate it from CSC in the acute stage.

Morphological differences between optic disc collaterals and neovascularization on optical coherence tomography angiography

BACKGROUND

To study morphological features of optic disc venous collaterals (OVCs) and neovascularization of optic disc (NVD) on optical coherence tomography angiography (OCTA).

METHODS

Patients with OVCs and NVDs secondary to ischemic retinal diseases were prospectively enrolled. Multimodal imaging was performed using color fundus photography, fluorescein angiography (FA), and OCTA. Morphological evaluation of en-face structural OCT, cross-sectional and en-face OCTA was performed.

RESULTS

Twenty eyes (20 patients; OVCs: n = 10 and NVD: n = 10) were included. OVCs appeared as small, loopy vessels distinct from surrounding peripapillary capillaries on OCTA in the radial peripapillary capillary frame. NVDs appeared as a mesh of fine caliber, raised vessels best seen in the vitreous slab of OCTA. Flow signals in these vascular alterations correlated well with hyperfluorescence on FA.

CONCLUSIONS

OCTA provides improved visualization of NVDs and OVCs in ischemic retinal diseases such as diabetic retinopathy and retinal vein occlusions compared to conventional FA.

Optical methods for quantitative and label-free sensing in living human tissues: principles, techniques, and applications

We present an overview of quantitative and label-free optical methods used to characterize living biological tissues, with an emphasis on emerging applications in clinical tissue diagnostics. Specifically, this review focuses on diffuse optical spectroscopy, imaging, and tomography, optical coherence-based techniques, and non-linear optical methods for molecular imaging. The potential for non- or minimally-invasive assessment, quantitative diagnostics, and continuous monitoring enabled by these tissue-optics technologies provides significant promise for continued clinical translation.