The role of OCT-A in retinal disease management

Investigation of the effects of single and two-muscle horizontal rectus surgeries on macular microvasculature

PURPOSE

To investigate the changes in posterior segment hemodynamics caused by horizontal rectus muscle surgeries using the optic coherence tomography angiography (OCTA).

METHODS

Patients who underwent at least one horizontal rectus recession, resection, or combination surgery were included. The patients were evaluated with an OCTA preoperatively and 30 days postoperatively. Postoperative changes in superficial capillary plexus (SCP)-vessel density (VD), deep capillary plexus (DCP)-VD, foveal avascular zone (FAZ) area and choriocapillaris (CC)-flow area parameters were examined. The mean differences (Δ) for the parameters in which significant changes were detected in the whole operated eyes group were compared between the single- and two-muscle surgery groups.

RESULTS

Twenty-five eyes of 24 patients with an average age of 16.40 ± 6.75 years (5-29) were included. Of the eyes, 10 underwent single muscle recession surgery. Two-muscle surgeries were performed in 15 eyes. SCP-VD in the superior parafoveal region increased significantly postoperatively (53.23 ± 4.11% vs. 54.54 ± 3.67%, p = 0.032). For DCP-VD, there was a statistically significant increase in all zones, except the superior hemisphere and fovea regions (p < 0.05 for all). FAZ area did not change significantly (p = 0.207). There was a significant increase in the CC-flow area (2.171 ± 0.146 mm2 vs. 2.232 ± 0.115 mm2, p = 0.013). There was a significant difference between the two groups only for the Δ SCP-VD/parafovea superior value (-0.62 ± 0.98 vs. 1.57 ± 3.07, p = 0.019).

CONCLUSIONS

Conventional horizontal rectus muscle surgeries may cause alterations in posterior segment hemodynamics. The number of muscles incised does not seem to greatly affect the magnitude of changes that occur.

KEY MESSAGES

What is known • After conventional horizontal rectus muscle surgeries, the anterior ciliary arteries are not recanalized, instead, anterior segment blood flow is maintained by increasing the flow in the long posterior ciliary arteries. • Previous studies using Doppler ultrasonography have shown increased flow in the ophthalmic artery, central retinal artery and long posterior ciliary arteries. What is new • In this study, significant increases were observed in superficial and deep capillary plexus-vessel density and choriocapillaris-flow area parameters in the first postoperative month with optic coherence tomography angiography device. • Hemodynamic increases in both retinal and choroidal vasculature were detected in the early period after conventional horizontal rectus muscle surgeries. • The number of muscles incised does not seem to greatly affect the magnitude of changes that occur.

Vascular imaging findings in retinopathy of prematurity

Retinopathy of prematurity (ROP) is a vascular disease among preterm infants involving incomplete or abnormal retinal vascularization and is a leading cause of preventable blindness globally. Measurements of ocular blood flow originating from a variety of imaging modalities, including colour Doppler imaging (CDI), fluorescein angiography (FA) and ocular coherence tomography angiography (OCTA), have been associated with changes in ROP patients. Herein, we discuss and summarize the relevant current literature on vascular imaging and ROP reviewed through December 2022. Differences in vascular imaging parameters between ROP patients and healthy controls are reviewed and summarized. The available data identify significantly increased peak systolic velocity (PSV) in the central retinal artery and ophthalmic artery as measured by CDI, increased vascular tortuosity as measured by FA, smaller foveal avascular zone (FAZ) as measured by FA and OCTA, and increased foveal vessel density (VD) and reduced parafoveal VD as measured by OCTA in ROP patients compared with controls. None of the above findings appear to reliably correlate with visual acuity. The studies currently available, however, are inconclusive and lack robust longitudinal data. Vascular imaging demonstrates the potential to aid in the diagnosis, management and monitoring of ROP, alongside retinal examination via indirect ophthalmoscopy and fundus photography.

Bessel Beams in Ophthalmology: A Review

The achievable resolution of a conventional imaging system is inevitably limited due to diffraction. Dealing with precise imaging in scattering media, such as in the case of biomedical imaging, is even more difficult owing to the weak signal-to-noise ratios. Recent developments in non-diffractive beams such as Bessel beams, Airy beams, vortex beams, and Mathieu beams have paved the way to tackle some of these challenges. This review specifically focuses on non-diffractive Bessel beams for ophthalmological applications. The theoretical foundation of the non-diffractive Bessel beam is discussed first followed by a review of various ophthalmological applications utilizing Bessel beams. The advantages and disadvantages of these techniques in comparison to those of existing state-of-the-art ophthalmological systems are discussed. The review concludes with an overview of the current developments and the future perspectives of non-diffractive beams in ophthalmology.

Macular vascularisation changes analysed using OCT angiography after successful rhegmatogenous retinal detachment repair

AIM

To analyse the macular vascularisation changes analysed using optical coherence tomography angiography (OCTA) after successful rhegmatogenous retinal detachment (RRD) repair by comparing gas vs silicone oil and macula-on vs macula-off.

METHODS

This retrospective data collection included 77 eyes with RRD that underwent pars plana vitrectomy (PPV) and gas or silicone oil tamponade. We performed an OCTA during the postoperative control between 6 and 24mo after the last surgery and evaluated the main parameters measured by OCTA: foveal avascular zone (FAZ) and parafoveolar vascular density (PVD) in the superficial capillary plexus. The patients were divided into four groups: RRD with macular involvement treated with gas tamponade, RRD without macular involvement treated with gas tamponade, RRD with macular involvement treated with silicone oil tamponade and RRD without macular involvement treated with silicone oil tamponade. A one-way ANOVA test combined with post hoc Bonferroni corrections compared FAZ sizes and PVD in all four groups.

RESULTS

The FAZ size was statistically significantly larger in eyes with RRD involving the macula than in those not involving it (P=0.005). There was no statistically significant difference in the FAZ sizes of the eyes treated with silicone oil tamponade compared to those treated with gas tamponade (P=0.54). There was no statistically significant difference in the PVD comparing all four groups.

CONCLUSION

Despite the known risks associated with silicone oil, our findings suggest that the type of tamponade used during PPV to treat an RRD has no significant effect on the future integrity of the PVD or the size of the FAZ in the superficial capillary plexus as measured by OCTA.

Benefits and Limitations of OCT-A in the Diagnosis and Follow-Up of Posterior Intraocular Inflammation in Current Clinical Practice: A Valuable Tool or a Deceiver?

Purpose: Optical coherence tomography angiography (OCT-A) has been applied to uveitis and intraocular inflammation since its availability after 2014. The imaging of retinal and choroidal vascularization without the use of dyes was a major development and represented a potentially valuable tool in ocular research. In addition to such use, OCT-A is often put forward as being able to potentially replace invasive methods needing dye injection, such as fluorescein angiography (FA) and indocyanine green angiography (ICGA). The aim of this review was to establish whether OCT-A was sufficiently useful in everyday routine clinical practice to monitor disease evolution and to perform treatment adjustments to the extent that it could reliably replace the standard dye methods. Methods: Selective literature review and analysis of own data and experience. Results: OCT-A is a technologically high-grade imaging modality allowing to analyze retinal circulation in inflammatory diseases of the posterior pole with a high sensitivity useful for research purposes. However, there is no evidence that it reaches equal effectiveness in the routine management of posterior uveitis involving the retina. OCT-A is unable to show leakage. In choriocapillaritis involving pre-capillary vessels, it shows capillary drop-out but does not seem to have an advantage over ICGA except that it can be repeated easily, not being invasive, and so allows a closer follow-up. It is, however, less useful in end-choriocapillary non-perfusion, such as in MEWDS. For choroidal stromal inflammation, OCT-A is ill-suited as it only shows inconsistent secondary circulatory changes produced by choroidal foci. OCT-A seems to be useful in the diagnosis and follow-up of inflammatory chorioneovascularisation (iCNV), although dye exams are more precise in showing the activity of the iCNV. Conclusion: In summary, OCT-A is a very sensitive modality for the retinal circulation in uveitis for research purposes; it is sometimes useful for close follow of choriocapillary drop-out but not in end-capillary non-perfusion. Its use for monitoring purposes in stromal choroiditis, however, is questionable. Its claim to possibly replace classical angiographic work-up for the practical management of posterior uveitis is largely overrated.

Optical Coherence Tomography Angiography: Clinical Utility and Future Directions

Purpose

This work aims to review the principles of optical coherence tomography angiography (OCTA), to survey its clinical utility, and to highlight the strengths of this technology as well as barriers to adoption.

Methods

A literature review with editorial discussion of the current applications for OCTA is presented.

Results

There have been recent advances in multiple domains in OCTA imaging, including devices, algorithms, and new observations pertaining to a range of pathologies. New devices have improved the scanning speed, signal-to-noise ratio, and spatial resolution and offer an increased field of view. New algorithms have been proposed to optimize image processing and reduce artifacts. Numerous studies employing OCTA have been published describing changes to the microvasculature in diabetic retinopathy, age-related macular degeneration, central serous chorioretinopathy, retinal vein occlusion, and uveitis.

Conclusions

OCTA provides noninvasive, high-resolution volumetric scans of the retinal and choroidal vasculature. OCTA can provide valuable data to augment traditional dye-based angiography in a range of chorioretinal diseases.

Evaluation of macular vessel density changes after strabismus surgery using optical coherence tomography angiography

PURPOSE

To compare retinal vessel density before and after strabismus surgery using swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

In this longitudinal, single-arm pilot study, vascular density in the deep capillary plexus (DCP), superficial retinal capillary plexus (SCP) and choriocapillaris layer (CCL) in consecutive subjects undergoing strabismus surgery was assessed using SS-OCTA preoperatively (T0), on the first day postoperatively (POD1), and 30 days postoperatively (POD30).

RESULTS

A total of 92 eyes of 56 patients (54% males) were included. Mean patient age was 41.1 ± 22.7. OCT vascular density of the DCP was 50.20 ± 5.57 at T0, 52.74 ± 4.77 at POD1, and 50.92 ± 4.58 at POD30. The differences were statistically significant for T0 versus POD1 (P < 0.05). Vascular density of the CCL was 50.72 ± 4.80 at T0, 53.59 ± 3.65 at POD1, and 51.39 ± 4.64 at POD30. The differences were statistically significant for T0 versus POD1 (P < 0.05). No significant differences were found in SCP (P > 0.05).

CONCLUSIONS

Transitory hemodynamic changes can occur in the DCP and in the CCL following muscle recession procedures.

Vascular biomarkers from optical coherence tomography angiography and glaucoma: where do we stand in 2021?

Biomarkers of ocular blood flow originating from a wide variety of imaging modalities have been associated with glaucoma onset and progression for many decades. Advancements in imaging platforms including optical coherence tomography angiography (OCTA) have provided the ability to quantify vascular changes in glaucoma patients, alongside traditional measures such as retinal nerve fibre layer thickness and optic nerve head structure. Current literature on vascular biomarkers, as measured by OCTA, indicates significant relationships between glaucoma and blood flow and capillary density in the retina and ONH. The data currently available, however, are highly diverse and lack robust longitudinal data on OCTA vascular outcomes and glaucoma progression. Herein we discuss and summarize the relevant current literature on OCTA vascular biomarkers and glaucoma reviewed through March 1, 2021. Associations between OCTA vascular biomarkers and clinical structural and functional glaucoma outcomes as well as differences between glaucoma patients and healthy controls are reviewed and summarized. The available data identify significantly decreased flow density, flow index and vessel density in the ONH, peripapillary vascular layer and macula of glaucoma patients compared with controls. Whole image vessel density is also significantly decreased in glaucoma patients compared with controls, and this outcome has been found to correspond to severity of visual field loss. OCTA vascular biomarkers alongside clinical structural outcomes may aid in assessing overall risk for glaucoma in patients.

Optical coherence tomography angiography in healthy children: normative data and age-related changes in microvascular structure of the optic disk and macula

PURPOSE

To determine normative data and reference ranges according to age groups by measuring the foveal avascular zone (FAZ), superficial capillary plexus vascular density (SCP-VD), deep capillary plexus vascular density (DVP-VD), radial peripapillary capillary plexus vessel density (RPC-VD), and peripapillary retinal nerve fiber layer (ppRNFL) in healthy children and to determine the age and sex-related changes of these values.

METHODS

This prospective study included data from 370 eyes of 370 healthy children (202 girls, 168 boys) aged 7-18 years. Participants were divided into four groups according to their age. Optical coherence tomography angiography (OCTA) measurements were taken using AngioVue (Avanti; Optivue).

RESULTS

No statistically significant difference was observed in terms of FAZ, SCP-VD, DCP-VD, RPC-VD, and ppRNFL thickness values according to the age groups (except the RPC-VD superior) (p > 0.05 for all). VDs in all deep parafoveal regions in groups 1 and 2 were higher in girls. While FAZ values were higher in girls in all age groups (statistically significant in groups 1, 3, and 4), ad SPD and DPD values were higher in boys in all age groups (statistically significant in group 1 and 2 for SPD, and group 1 and 3 for DPD).

CONCLUSIONS

We report normal reference ranges for macula and disk vessel density and ppRNFL parameters in healthy children aged 7-18 years using OCTA. These normative values could be useful in diagnosing retina and optic disk disease early in childhood.

Assessment of the retinal vasculature in healthy Chinese preschool children aged 4-6 years old using optical coherence tomography angiography

PURPOSE

To establish normal parameters of macular and optic disc vasculature by optical coherence tomography angiography (OCTA) in healthy preschool children aged 4-6 years old in China. OCTA reflects retinal metabolism and development in children at these ages and could be used clinically and in future studies to aid diagnosis and prediction of retinal abnormalities and developmental stagnation.

METHODS

In this cross-sectional study, we measured foveal, parafoveal, and perifoveal vessel density in the superficial capillary plexus (SCP); the deep capillary plexus (DCP), the foveal avascular zone (FAZ), and the radial capillary peripapillary (RPC) in the optic disc using investigational spectral-domain OCTA. The magnification effect of the FAZ area and microvasculature measurements was corrected by Littman and the modified Bennett formula.

RESULTS

A total of 242 eyes (116 males and 126 females, 5.31 ± 0.73 years) were recruited for the analysis. The mean macular vessel density was 48.10 ± 2.92% and 48.74 ± 6.51% in the SCP and the DCP, respectively. The RPC vessel density was 47.17 ± 2.52%, 47.99 ± 4.48%, and 48.41 ± 3.07% in the whole image, inside disc, and peripapillary, respectively; and the mean FAZ area was 0.28 ± 0.11 mm². A significant difference between male and female participants was found in the retinal vasculature (DCP, SCP, and RPC). None of these parameters were significantly different in age (P > 0.05), except that DCP slightly increased with aging. The right and left eyes had good consistency in the parameters of the macula and optic disc.

CONCLUSIONS

Our study establishes the macular and optic disc OCTA reference values in 4- to 6-year-old healthy preschool children. They may be used in longitudinal OCTA studies and clinical applications.

Imaging Biomarkers and Their Impact on Therapeutic Decision-Making in the Management of Neovascular Age-Related Macular Degeneration

These recommendations, produced by a group of Canadian retina experts, have been developed to assist both retina specialists and general ophthalmologists in the management of vision-threatening neovascular age-related macular degeneration (nAMD). The recommendations are based on published evidence as well as collective experience and expertise in routine clinical practice. We provide an update on practice principles for optimal patient care, focusing on identified imaging biomarkers, in particular retinal fluid, as well as current and emerging therapeutic approaches. Algorithms for delivering high-quality care and improving long-term patient outcomes are provided, with an emphasis on timely and appropriate treatment to preserve and maintain vision. In the context of nAMD, increasing macular fluid or leakage on fluorescein angiography (FA) may indicate disease activity regardless of its location. Early elimination of intraretinal fluid (IRF) is of particular relevance as it is a prognostic indicator of worse visual outcomes. Robust referral pathways for second opinion and peer-to-peer consultations must be in place for cases not responding to intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy.

High body weight-related retinal vasculopathy in children with obesity

PURPOSE

To investigate the foveal avascular zone (FAZ) and the microvascular alterations in both macula and peripapillary region in obese children.

METHODS

We included a total of 222 eyes of 111 children (54 obese children and 57 healthy subjects). Capillary vessel density (VD) of superficial (SCP) and deep (DCP) retinal capillary plexuses were measured in macular slabs. Peripapillary region was also evaluated. The FAZ parameters were measured based on the whole retinal slab. A commercial optical coherence tomography-angiography system was used.

RESULTS

The mean ages were 13.33 ± 2.55 years (range, 8-17) and 13.41 ± 2.90 years (range, 7-18) in patients with obesity and healthy controls, respectively (p = 0.84). The mean area of the FAZ were 0.278 ± 0.10 mm2 and 0.272 ± 0.11 mm2 in children with obesity and in control participants, respectively (p = 0.68). There were significant increases in the superior region of the parafoveal VD of SCP (p = 0.008 for superior hemisphere and p = 0.003 for superior quadrant). There was no significant difference in any measure of the macular DCP and peripapillary region (p > 0.05, for all).

CONCLUSION

Increased vascular density measurements were found in the superior part of the parafoveal region of SCP in children with obesity. The results of the study should be taken into consideration during the course of the disease to define whole systemic response to obesity in childhood and will be of interest for pediatrician's clinical practice.

Clinical Utility of Artificial Intelligence Algorithms to Enhance Wide-Field Optical Coherence Tomography Angiography Images

The aim of this paper is to investigate the clinical utility of the application of deep learning denoise algorithms on standard wide-field Optical Coherence Tomography Angiography (OCT-A) images. This was a retrospective case-series assessing forty-nine 10 × 10 mm OCT-A1 macula scans of 49 consecutive patients attending a medical retina clinic over a 6-month period. Thirty-seven patients had pathology; 13 had none. Retinal vascular layers were categorised into superficial or deep capillary plexus. For each category, the retinal experts compared the original standard image with the same image that had intelligent denoise applied. When analysing the Superficial Capillary Plexus (SCP), the denoised image was selected as "best for clinical assessment" in 98% of comparisons. No difference was established in the remaining 2%. On evaluating the Deep Capillary Plexus (DCP), the denoised image was preferred in 35% of comparisons. No difference was found in 65%. There was no evidence of new artefactual features nor loss of anatomical detail in denoised compared to the standard images. The wide-field denoise feature of the Canon Xephilio OCT-A1 produced scans that were clinically preferable over their original OCT-A images, especially for SCP assessment, without evidence for causing a new artefactual error.

Gastric Bypass Improves Microvascular Perfusion in Patients with Obesity

PURPOSE

Basic science research has shown that obesity is associated with microvascular endothelial dysfunction. However, whether bariatric surgery impacts the microvascular networks has yet to be explored. This study sought to evaluate the impact of gastric bypass in the retinal microvasculature.

METHODS

Patients with obesity (BMI ≥ 35 kg/m²) scheduled to gastric bypass were consecutively recruited and included in the study. Patients were evaluated before surgery and 6-12 months after the intervention. Macular microvascular properties were evaluated using optical coherence tomography (OCT) angiography. Foveal avascular zone area, perimeter, circularity, and foveal and perifoveal vascular density (in both superficial and deep vascular plexus) were computed.

RESULTS

In total, 40 eyes from 20 patients were included (30% male, mean BMI 43.4 ± 4.5 kg/m² (range 35.7-51.4). From these, 45% were diabetic before bariatric surgery. After surgery, there was a significant increase in foveal avascular zone circularity (from 0.85 ± 0.09 to 0.92 ± 0.07, p = 0.001) and vascular density in perifoveal deep vascular plexus (from 0.69 ± 0.12 to 0.73 ± 0.12; p = 0.04), whereas foveal avascular zone perimeter decreased (from 2.34 ± 0.37 to 2.20 ± 0.35 mm, p = 0.007). Preoperative diabetic status was not a predictor of microvascular retinal changes after bariatric surgery. However, after multivariate adjustments, the increased drop in HbA1c after the surgery remained associated with the increase in perifoveal vascular density in the deep vascular plexus (B = 0.05; 95% CI 0.05-0.10; p = 0.03).

CONCLUSIONS

Gastric bypass improves retinal microvascular perfusion as demonstrated by the increased parafoveal vascular density in the deep vascular plexus, increased foveal avascular zone circularity, and decreased foveal avascular zone perimeter.

Normative Data Assessment of Peripapillary and Macular Vessel Density and Foveal Avascular Zone Metrics Using Optical Coherence Tomography Angiography in Children

PURPOSE

To quantify the vessel density of the macula and optic disc and foveal avascular zone (FAZ) in healthy children and to evaluate the effects of age, gender, axial length, body mass index (BMI), and refractive errors on vessel density and FAZ.

METHODS

This study enrolled 92 eyes of 92 participants (42 boys and 50 girls). Optical coherence tomography angiography (OCTA) was performed using AngioVue (Avanti; Optivue). FAZ area, nonflow area, superficial and deep vessel density, FAZ perimeter, acircularity index of FAZ, foveal density, and radial peripapillary capillary vessel density were analyzed by gender. Correlations between the investigated OCTA parameters and age, axial length, and BMI were evaluated.

RESULTS

Girls had significantly larger nonflow and FAZ area than boys (P = .01 and .02). Superficial and deep vessel density at the fovea was significantly higher in boys compared to girls (P = .01 and .03). Inferior temporal and superior temporal Radial peripapillary capillary vessel densities were significantly higher in girls than boys (P = .01 and .03). No significant difference was found in the macular and optic disc vessel density measurements within refractive groups (P > .05, for all). Regarding the correlation of age with FAZ and vessel density parameters, only nonflow area was positively correlated with age (r = 0.22, P = .03).

CONCLUSIONS

This study provides normative data for children. Although boys had greater foveal vessel density, girls had greater FAZ area and nonflow area. Refractive status of the eye and BMI did not influence the OCTA parameters. Although nonflow area was positively correlated with age, other parameters were steady within the ages of 7 to 18 years. [J Pediatr Ophthalmol Strabismus. 2020;57(6):388-398.].

Peripapillary Retinal Vascular Involvement in Early Post-COVID-19 Patients

The ability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2's) to cause multi-organ ischemia and coronavirus-induced posterior segment eye diseases in mammals gave concern about potential sight-threatening ischemia in post coronavirus disease 2019 patients. The radial peripapillary capillary plexus (RPCP) is a sensitive target due to the important role in the vascular supply of the peripapillary retinal nerve fiber layer (RNFL). Eighty patients one month after SARS-CoV-2 infection and 30 healthy patients were selected to undergo structural OCT (optical coherence tomography) and OCTA (optical coherence tomography angiography) exams. Primary outcome was a difference in RPCP perfusion density (RPCP-PD) and RPCP flow index (RPCP-FI). No significant difference was observed in age, sex, intraocular pressure (IOP) and prevalence of myopia. RPCP-PD was lower in post SARS-CoV-2 patients compared to controls. Within the post-COVID-19 group, patients with systemic arterial hypertension had lower RPCP-FI and age was inversely correlated to both RPCP-FI and RPCP-PD. Patients treated with lopinavir + ritonavir or antiplatelet therapy during admission had lower RPCP-FI and RPCP-PD. RNFL average thickness was linearly correlated to RPCP-FI and RPCP-PD within post-COVID-19 group. Future studies will be needed to address the hypothesis of a microvascular retinal impairment in individuals who recovered from SARS-CoV-2 infection.

Providing a Safe and Effective Intravitreal Treatment Service: Strategies for Service Delivery

An aging population leads to increasing demand for medical retina services with chronic diseases being managed in long-term care pathways. Many hospital services struggle to deliver efficient and effective MR care due, at least in part, to infrastructure that does not expand responsively enough to meet the increased demand. A steering committee of retinal specialists from a variety of UK NHS hospital ophthalmology departments with experience of leading and managing NHS retinal services in the intravitreal era came together for the generation of this document to review and compile key aspects that should be considered when optimising intravitreal treatment capacity within MR services. This article aims to provide a useful collation and signposting of key published evidence, consensus and insights on aspects of delivering an intravitreal service, including treatment regimens, virtual clinics, staff training and governance, telemedicine and information technology, and data collection and key performance indicators. The objective is to equip ophthalmologic healthcare professionals with the necessary tools to develop and adapt their local service in the face of current and projected increased demand.

[Indications for fluorescein angiography and optical coherence tomography angiography (OCTA) in medical retina: Changes from 2015 and 2018]

INTRODUCTION

Non-invasive multimodal imaging, including optical coherence tomography angiography (OCTA), has demonstrated high sensitivity and specificity for the management of retinal diseases. Since the availability of OCTA in 2015, we have developed a policy of "as little fluorescein angiography as possible". In this study, we describe the rate of OCTA and fluorescein angiography (FA) performed and their indications.

METHODS

Retrospective descriptive single-centre study. Chart review of patients examined for retinal disorders by one medical retina specialist between January 2015 and June 2018.

RESULTS

3487 patients were examined for a retinal disease. The charts of 651 of these patients (1170 eyes) were randomly selected for analysis (study group). The mean age in the study group was 72 years (60% female). Overall, OCTA and FA were performed in 49.4% and 6.5% of the studied eyes respectively. After the first year, the rate of FA decreased to 2%. The main indications for OCTA were age-related macular degeneration (AMD): 50%, central serous chorioretinopathy (CSC): 12% and retinal vascular occlusion: 10%. The most frequent indications for FA were AMD: 49%, diabetic retinopathy (DR): 18% and CSC: 14%. FA was performed in 16%, 11% and 10% of eyes diagnosed with DR, CSC and AMD respectively (P<0.05).

CONCLUSION

In routine practice, OCTA was performed in half of the eyes examined for a retinal disorder. The overall rate of FA was 6.5% and dropped to 2% after the first year of OCTA use. DR was the main disorder still requiring FA.

Foveal avascular zone and vessel density in children with attention deficit hyperactivity disorder

PURPOSE

To compare the retinal and choroidal microvasculature quantitatively via optical coherence angiography (OCTA) in children with attention deficit hyperactivity disorder (ADHD) who were under methylphenidate (MFD) treatment or newly diagnosed as ADHD and were not taking any medication.

METHODS

This was a cross-sectional, comparative, and observational study. The children who were between 6 and 17 years old and previously diagnosed as ADHD and were under MFD treatment or who were newly diagnosed as ADHD were included in the study. Optical coherence tomography angiography imaging was performed via OCT RT XR Avanti with AngioVue software (Optivue Inc, Freemont, CA). The main outcome measure of the study was OCTA parameters of the children with ADHD.

RESULTS

A total of 186 eyes of 186 patients were included in the study. There were 80 eyes in the control group (newly diagnosed) and 106 eyes in the treatment group (under MFD treatment). The mean duration of methylphenidate use in the treatment group was 33.9 ± 20.1 months (between 6 and 84 months). The choriocapillary flow area (p = 0.03), superficial parafoveal thickness (p = 0.01), and deep parafoveal thickness (p = 0.01) were statistically greater in the treatment group than the control group.

CONCLUSION

Most of the important OCTA parameters especially foveal avascular zone (FAZ) area and FAZ perimeter were similar in the two groups. There was a significant difference between the two groups in parafoveal thickness values which might point to a slight effect of MFD on retinal circulation.

Associations between Macular OCT Angiography and Nonproliferative Diabetic Retinopathy in Young Patients with Type 1 Diabetes Mellitus

METHODS

OCTA of both eyes was performed in a cross-sectional study of 14 to 30-year-old individuals with at least 10-year duration of T1D and controls recruited from the Norwegian Atherosclerosis and Childhood Diabetes (ACD) study. Vessel density (VD) and foveal avascular zone (FAZ) area in the superficial and deep capillary plexus (SCP and DCP), total retinal volume (TRV), and central macular thickness (CMT) were calculated using automated software. Univariate and multivariate ordered logistic regression (OLR) models were used accordingly.

RESULTS

We included 168 control eyes and 315 T1D eyes. Lower VD in DCP (OR 0.65, 95% CI 0.51-0.83), longer diabetes duration (OR 1.51, 95% CI 1.22-1.87), and higher waist circumference (OR 1.08, 95% CI 1.02-1.14) were significantly associated with progression of NPDR. VD in SCP and DCP were significantly lower in T1D patients without diabetic retinopathy than in controls.

CONCLUSIONS

Sparser VD in DCP is significantly associated with severity of NPDR, supporting that OCTA might detect the earliest signs of NPDR before it is visible by ophthalmoscopy.

The vascular densities of the macula and optic disc in normal eyes from children by optical coherence tomography angiography

PURPOSE

This study aims to describe the variation and characteristics of vessel density (VD) of the macula and optic disc in the normal eyes of children.

METHODS

This was a retrospective study where subjects aged 5-18 years with normal eyes were enrolled. The macula and optic disc were scanned by optical coherence tomography angiography (OCTA). The influences of age, gender, and axial length (AL) on VD were analyzed.

RESULTS

A total of 71 normal eyes from 71 subjects were enrolled. For the macula, the mean VD of fovea, parafovea, and perifovea at superficial retina and deep retina were 20.1%, 50.2%, 49.4%, 36.1%, 53.9%, and 48.1%, respectively. The mean foveal avascular zone (FAZ) was 0.277 mm². For optic disc, the mean VD of radial peripapillary capillary (RPC) and inside-disc areas were 51.8% and 51.7%, respectively. Significant differences were found between the superior-hemi and inferior-hemi VD of the superficial retinal parafovea, deep retinal perifovea, and perifovea. The fovea VD of the superficial and deep retina and FAZ areas were different between genders. The inside-disc VD was positively correlated with AL, while other VDs had no significant correlation with age and AL.

CONCLUSIONS

The parafovea VD of the superficial retina, parafovea, and perifovea of the deep retina had superior-hemi VD; boys had a higher fovea VD and smaller FAZ area than those of girls, the macular VD and peripapillary RPC density were steady for 5-18 year-olds. This study provided useful information for furthering the understanding of the development mode of vessel in children and the OCTA clinical applications in children.

Anterior Segment Applications of Optical Coherence Tomography Angiography

Purpose: To review the current literature regarding optical coherence tomography angiography (OCT-A) applications in the anterior segment. Methods: A literature search was performed for terms including OCT-Angiography, anterior segment, cornea, conjunctiva, iris, applications and use in ophthalmology. Results: Fifteen studies were identified, 14 in human subjects. Studies with OCT-A of the conjunctiva, episclera, cornea, and iris were identified, some with normal eyes imaged and others with various pathologies. Most of these studies imaged corneal neovascularization. Three studies described protocols used for image acquisition, one of which was referenced by two later papers. Conclusions: OCT-A is a noninvasive technology with recent applications in the anterior segment. Several pilot studies have been performed on various anterior segment structures and disease states however standardization of image acquisition techniques is still needed. Future imaging could allow noninvasive and serial monitoring of pathology as well as recurrence after therapeutic intervention.

Quantification and Repeatability of Vessel Density and Flux as Assessed by Optical Coherence Tomography Angiography

Purpose

To determine the intrasession repeatability (test-retest variability) of parafoveal and peripapillary perfused capillary density (PCD) and normalized flux index (NFI) as assessed with Canon OCT-HS100 angiography.

Methods

Pairs of optical coherence tomography angiography (OCT-A) images were obtained from the parafoveal and peripapillary region of 30 eyes of 30 healthy subjects. PCD and NFI were calculated using generic image-processing software. Macular ganglion-cell complex thickness (GCC) and peripapillary retinal nerve fiber layer thickness (RNFLT) were also recorded. Bland-Altman analysis was performed and the coefficient of repeatability (CoR) and intraclass correlation coefficient (ICC) were calculated. Correlations of parafoveal PCD/NFI with GCC and of peripapillary PCD/NFI with RNFLT were also computed.

Results

Mean (standard deviation) parafoveal and peripapillary PCD were 40.0% (1.8%) and 44.5% (1.3%), respectively. Corresponding values for NFI were 151.2 (6.8) and 164.2 (3.9). For PCD, ICC was 0.76 for parafoveal and 0.79 for peripapillary measurements; corresponding CoRs were 2.7% and 1.8%. Corresponding values for NFI were 0.62 and 0.67 for ICC and 13.3 and 7.0 for CoR. Average measures ICC was 0.87/0.88 and 0.76/0.80 for the parafoveal/peripapillary PCD and NFI, respectively. PCD and NFI were weakly correlated with GCC (r = 0.39, P = 0.035; r = 0.33, P = 0.077) and moderately correlated with RNFLT (r = 0.43, P = 0.017; r = 0.55, P = 0.002).

Conclusions

Repeatability of a commercially available OCT-A with generic image-processing software was good (NFI) to excellent (PCD). Our results indicate that changes surpassing the variability in healthy subjects should be easily detectable in a clinical setting.

Translational Relevance

Repeatability estimates provide information regarding the relevance of changes in retinal perfusion.

Vessel density and En-face segmentation of optical coherence tomography angiography to analyse corneal vascularisation in an animal model

Background

Optical coherence tomography angiography (OCTA) is a novel non-invasive angiography technology that has recently been extensively studied for its utility in anterior segment imaging. In this study, we compared a split-spectrum amplitude decorrelation angiography (SSADA) OCTA and an Complex OCT signal difference angiography [corrected] (CODAA SD) [corrected] OCTA system to current angiographic technique, indocyanine green angiography (ICGA), to assess corneal vascularisation in an animal model.

Methods

We imaged 16 rabbits, (one eye per animal) with corneal vascularisation using SSADA OCTA (AngioVue; Optovue Inc., USA), CODAA OCTA [corrected] (Angioscan; RS-3000 Nidek Co. Ltd., Japan) and ICGA in the same region of interest of the cornea at successive time-points. We then analysed all scanned images for vessel density measurements and used paired t-tests and Bland-Altman plots to examine for significant differences. The en-face segmentation images from each of the OCTA scans were also extracted and were matched at every 50 μm segmentation to be compared for vessel density at the respective depths.

Results

Bland-Altman plots revealed a good agreement between all three imaging techniques (P > 0.05) for all vessel density measurements computed, and the ranges of 95% limit of agreement were acceptable from a clinical perspective. No significant difference was reported, with ICGA (μ = 16.52 ± 8.94%) being more comparable to the CODAA [corrected] OCTA (μ = 16.23 ± 9.51%; p = 0.50) than the SSADA OCTA (μ = 17.09 ± 7.34%; p = 0.33) system. Also, a good correlation value (r > 0.9) was obtained when comparing the vessel density measurements of the en-face segmentations between the OCTA systems.

Conclusions

Comparable vessel density quantification between the two OCTA systems, and with ICGA was obtained. Segmentation analysis of the vasculature at different depths showed varied performance in the two OCTA systems relative to each other. The implications of the study may help to aid in the development of better OCTA algorithms for the anterior segment and its use in clinical translational research.

Optical Coherence Tomography Angiography in Eyes with Non-infectious Posterior Uveitis; Some Practical Aspects

Optical coherence tomography angiography (OCTA) is an innovative imaging technology enabling clinicians to learn more about the pathophysiology of disease processes as it facilitates visualization of the retinal and choroidal circulation without injection of a dye. Also it provides ample qualitative and quantitative data on the vascular supply. OCTA has become an important tool nowadays in the diagnosis and follow-up of patients with age-related macular degeneration, inherited chorioretinal diseases, diabetic retinopathy, retinal vascular occlusive diseases and optic nerve disorders. However, its place is relatively less known in non-infectious posterior uveitis (NIPU). OCTA may help mainly in assessing macular and peripheric retinal perfusion status, detection of retinal and/or disc neovascularization, diagnose of inflammatory choroidal neovascularization and visualizing the uveitic white-dot lesions. This mini-review describes the use of OCTA in patients with NIPU and summarizes some practical points in several uveitic entities.