The Role of Optical Coherence Tomography Angiography in the Management of Uveitis

Evaluation of Optical Coherence Tomography Angiography Findings in Pars Planitis and Multiple Sclerosis Associated Intermediate Uveitis in Remission

PURPOSE

To evaluate the microvasculature during remission in patients with pars planitis (PP-IU) and multiple sclerosis-associated intermediate uveitis (MS-IU) using optical coherence tomography angiography (OCT-A).

METHODS

Single-center, descriptive, case-control study was conducted. Adult patients (≥16 years) with IU in remission (PP-IU and MS-IU) and healthy age-sex matched healthy controls (HC) were enrolled to the study. Demographic/clinical features, best-corrected visual acuity (BCVA), ocular findings, neurological symptoms and preferred treatments were recorded. The presence of cystoid macular edema (CME) during follow-up was recorded. All IU patients in remission and HC subjects were scanned with OCT-A. Foveal avascular zone (FAZ) areas of superficial and deep capillary plexus (SCP/DCP) and vascular densities of SCP, DCP and choriocapillaris were obtained from OCT-A and compared between the groups.

RESULTS

Sixty-nine eyes of 37 IU patients in remission and 20 HC were included (44 eyes/23 patients in PP-IU, 25/14 in MS-IU, 40/20 in HC). No statistically significant differences were observed in terms of demographic or clinical characteristics of the patients. The vascular density in the SCP was significantly reduced in the PP-IU and MS-IU groups compared to the HC group (p < .05). Nevertheless, there were no significant changes in any of the OCTA parameters between the IU groups. Uveitis duration was found to be correlated with enlargement of the FAZ area in PP-IU (p = .039).

CONCLUSION

OCTA may not be useful in differentiating between PP-IU and MS-IU. Nevertheless, the primary implication in SCP potentially elucidates the pathogenesis of these two subtypes of IU, which are characterized by a shared pathogenesis. The monitoring of the FAZ area in the PP-IU group is valuable in terms of chronicity.

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.

Quantitative Analysis of the Choriocapillaris in Uveitis Using En Face Swept-Source Optical Coherence Tomography Angiography

PURPOSE

To perform a quantitative analysis of choriocapillaris (CC) flow deficits (FDs) in patients with uveitis.

DESIGN

Retrospective cross-sectional study.

METHODS

Swept-source optical coherence tomography based angiography (SS-OCTA) macular volume scans (3 × 3 mm and 6 × 6 mm) were obtained using the Plex Elite 9000. En face CC images were generated and analyzed using an automated FD identification algorithm. Three quantitative metrics were determined for each eye: FD number (FDN), mean FD size (MFDS), and FD density (FDD). Quantitative metrics were compared between uveitis and control eyes. The uveitis cohort was further subdivided by the presence or absence of choroidal involvement, and quantitative metrics were compared between subgroups and normal control subjects.

RESULTS

A total of 38 eyes from 38 control subjects and 73 eyes from 73 uveitis subjects were included in this study. Eyes with uveitis have significantly larger CC MFDS (3- × 3-mm scans; P < .0001; 6- × 6-mm scans; P < .0001) and higher FDD (P = .0002; P = .0076, respectively) compared to control eyes. Additional analysis determined that these differences were due to the choroidal disease subgroup, which demonstrates significantly larger MFDS (3 × 3 = 1,108 μm²; 6 × 6 = 1,104 μm²) compared to both normal control eyes (752 μm²; P < .0001; 802 μm²; P < .0001, respectively) and uveitis patients without choroidal involvement (785 μm²; P < .0001; 821 μm²; P < .0001, respectively). No significant differences were found between the quantitative metrics of control subjects and patients without choroidal involvement.

CONCLUSIONS

Automated quantification of CC can identify pathological FDs and provide quantitative metrics describing such lesions in patients with uveitis. Posterior uveitis patients have significantly larger CC FDs than patients with other forms of uveitis.

Advances in imaging of uveitis

Advances in multimodal imaging have significantly contributed to the management of many uveitis diseases in recent years. The most significant developments include the use of optical coherence tomography to obtain a more accurate and reproducible assessment of ocular inflammation, the application of optical coherence tomography angiography in choroiditis and retinal vasculitis, new possibilities for studying vitritis with ultrawide field imaging, and the most recent applications of fundus autofluorescence in uveitis. In this review, we provide an overview of the most significant advances in multimodal imaging of uveitis achieved in recent years.

The challenging management of Rift Valley Fever in humans: literature review of the clinical disease and algorithm proposal

Rift Valley Fever (RVF) is an emerging zoonotic arbovirus with a complex cycle of transmission that makes difficult the prediction of its expansion. Recent outbreaks outside Africa have led to rediscover the human disease but it remains poorly known. The wide spectrum of acute and delayed manifestations with potential unfavorable outcome much complicate the management of suspected cases and prediction of morbidity and mortality during an outbreak. We reviewed literature data on bio-clinical characteristics and treatments of RVF human illness. We identified gaps in the field and provided a practical algorithm to assist clinicians in the cases assessment, determination of setting of care and prolonged follow-up.

Optical coherence tomography angiography in uveitis

Before the introduction of optical coherence tomography angiography (OCTA) in the early 2000s, dye-based angiography was considered the “gold standard” for the diagnosis and monitoring of ocular inflammation. OCTA is a novel technique, which demonstrates capillary networks based on the amount of light returned from moving blood cells, providing further information on pathophysiological changes in uveitis.

The aim of this review is to describe the basic principles of OCTA and its application to ocular inflammatory disorders. It particularly emphasizes on its contribution not only in the diagnosis and management of the disease but also in the identification of possible complications, comparing it with fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA). Although the advent of OCTA has remarkably enhanced the assessment of uveitic entities, we highlight the need for further investigation in order to better understand its application to these conditions.

OCT Angiography: A Technique for the Assessment of Retinal and Optic Nerve Diseases in the Pediatric Population

Optical coherence tomography angiography (OCT-A) is a novel, rapidly evolving, non-invasive imaging technique that allows images of the retinal vasculature to be obtained in a few seconds. Blood vessels of different retinal vascular plexuses and the foveal avascular zone (FAZ) can be examined without the administration of any contrast or dye. Due to these characteristics, OCT-A could be an excellent complementary test to study retinal vascularization in children. Until now, most of the studies with OCT-A have been conducted in adults and only a few have been carried out in children. In this review, we describe the principles and advantages of OCT-A over traditional imaging methods and provide a summary of the OCT-A findings in retinopathy of prematurity and other retinal and optic disc pathologies in children. In view of the promising results from studies, the advantages of a relatively rapid and non-invasive method to assess the retinal vasculature makes OCT-A a tool of which applications in the field of pediatric ophthalmology will be expanded in the near future for patient diagnosis and follow-up in every day clinical practice.

Optical Coherence Tomography Angiography in Intermediate Uveitis

PURPOSE

To investigate the involvement of the retinal and choriocapillaris microvasculature in intermediate uveitis on optical coherence tomography angiography (OCT-A).

DESIGN

Case-control study.

METHODS

Patients and age-matched controls were imaged with swept-source OCT-A. Using ImageJ, superficial and deep retinal vasculature were semi-automatically analyzed for vessel (VD) and skeleton density (SD), vessel diameter index (VDI), and fractal dimension (FD). Choriocapillaris layer was automatically graded for mean signal intensity, signal intensity standard deviation, kurtosis of signal intensity distribution, and flow signal voids.

RESULTS

Twenty-nine intermediate uveitis eyes and 30 control eyes were included. Both superficial and deep retinal layers showed significant reduction in all OCT-A parameters (eg, superficial retinal layer: 0.31 vs 0.40 VD, 5.6e^-8 vs 6.4e^-8 SD, 5.4e⁶ vs 6.1e⁶ VDI, and 1.78 vs 1.79 FD, respectively, all P < .05). At the choriocapillaris layer a greater heterogeneity of perfusion with a shift toward a higher proportion of large confluent flow signal voids was present. Also in the absence of macular edema OCT-A parameters were reduced when compared with healthy controls (all parameters except for VDI in the superficial retinal layer and the choriocapillaris kurtosis and flow signal void analyses).

CONCLUSIONS

In intermediate uveitis, reduced vascular density and complexity in superficial as well as deep retinal layers and altered choriocapillaris perfusion are present. Moreover, these findings indicate impairment of the macular microvasculature even in the absence of macular edema. The results of our study may aid in the diagnosis as well as the monitoring of intermediate uveitis.

Optical coherence tomography angiography: A comprehensive review of current methods and clinical applications

OCT has revolutionized the practice of ophthalmology over the past 10-20 years. Advances in OCT technology have allowed for the creation of novel OCT-based methods. OCT-Angiography (OCTA) is one such method that has rapidly gained clinical acceptance since it was approved by the FDA in late 2016. OCTA images are based on the variable backscattering of light from the vascular and neurosensory tissue in the retina. Since the intensity and phase of backscattered light from retinal tissue varies based on the intrinsic movement of the tissue (e.g. red blood cells are moving, but neurosensory tissue is static), OCTA images are essentially motion-contrast images. This motion-contrast imaging provides reliable, high resolution, and non-invasive images of the retinal vasculature in an efficient manner. In many cases, these images are approaching histology level resolution. This unprecedented resolution coupled with the simple, fast and non-invasive imaging platform have allowed a host of basic and clinical research applications. OCTA demonstrates many important clinical findings including areas of macular telangiectasia, impaired perfusion, microaneurysms, capillary remodeling, some types of intraretinal fluid, and neovascularization among many others. More importantly, OCTA provides depth-resolved information that has never before been available. Correspondingly, OCTA has been used to evaluate a spectrum of retinal vascular diseases including diabetic retinopathy (DR), retinal venous occlusion (RVO), uveitis, retinal arterial occlusion, and age-related macular degeneration among others. In this review, we will discuss the methods used to create OCTA images, the practical applications of OCTA in light of invasive dye-imaging studies (e.g. fluorescein angiography) and review clinical studies demonstrating the utility of OCTA for research and clinical practice.