Swept-Source OCT Angiography of Serpiginous Choroiditis

Wide Field Optical Coherence Tomography and Optical Coherence Tomography Angiography in Uveitis

BACKGROUND

We review the current literature on the use of wide-field optical coherence tomography (OCT) and wide-field optical coherence tomography angiography (OCTA) in different uveitic phenotypes as well as various sequelae of uveitis and discuss the limitations of this evolving technology.

MAIN BODY

Current consensus guidelines on nomenclature in wide-field OCT and OCTA are described. The specific utility of wide-field OCT and OCTA in assessment of the retina and choroid using different en-face and cross-sectional slabs in various inflammatory diseases is reviewed. Furthermore, we discuss widefield OCT and OCTA in assessment of retinal ischemia and its limitations in assessing retinal vascular leakage.

CONCLUSION

Wide-field OCT and OCTA deliver more sensitive measures of inflammation. With continued advancement in both hardware technology and software processing, these modalities will allow for more accurate assessment of uveitis, better understanding of disease mechanisms, and precise monitoring of treatment response.

[Acute posterior multifocal placoid pigment epitheliopathy, serpiginous choroiditis and related diseases]

Acute Posterior Multifocal Placoid Pigment Epitheliopathy (APMPPE) and serpiginous choroiditis are two diseases classified as "white spot syndromes." Both are inflammatory/autoimmune diseases with suspected primary involvement of the choriocapillaris. The former usually has an excellent prognosis, while the latter can rapidly induce legal blindness. Whereas these diseases are well defined and well known, other entities (such as persistent placoid maculopathy or ampiginous choroiditis) with features of both APMPPE and serpiginous choroiditis have been described more recently. This review aims to describe demographic characteristics and multimodal imaging features to help differentiate between these four diseases.

Outcome Measures for Disease Monitoring in Intraocular Inflammatory and Infectious Diseases (OCTOMERIA): Understanding the Choroid in Uveitis with Optical Coherence Tomography (OCT)

PURPOSE

To compare imaging modalities for the choroid of the eye, and evaluate various choroidal changes in uveitides entities.

METHODS

A comprehensive systematic literature review was conducted looking at current imaging modalities available to assess choroid architecture and commonly used parameters available to qualify and quantify choroidal changes, before looking at specific uveitides entities with choroidal involvement which have been broadly separated into non-infectious and infectious in etiology.

RESULTS

We describe the various modalities currently available to evaluate the choroid of the eye such as Ultrasound B Scan, ICGA, and OCT. Choroidal changes in various ocular and systemic diseases such as Behcet's Disease, Sarcoidosis, Syphillis, Tuberculosis, and many more have been reported and published.

CONCLUSION

Multiple choroidal tomographic and angiotomographic findings have been demonstrated for evaluation in uveitis. These findings can manifest in multiple ocular and systemic diseases, and can be illustrated using the various imaging modalities at present. Future advancements in choroidal imaging would help to adapt these findings into parameters for clinical practice to properly evaluate these ocular and systemic diseases.

Imaging-based Assessment of Choriocapillaris: A Comprehensive Review

PURPOSE

Over the past two decades, advancements in imaging modalities have significantly evolved the diagnosis and management of retinal diseases. Through these novel platforms, we have developed a deeper understanding of the anatomy of the choroidal vasculature and the choriocapillaris. The recently developed tools such as optical coherence tomography (OCT) and OCT angiography (OCTA) have helped elucidate the pathological mechanisms of several posterior segment diseases. In this review, we have explained the anatomy of the choriocapillaris and its close relationship to the outer retina and retinal pigment epithelium.

METHODS

A comprehensive search of medical literature was performed through the Medline/PubMed database using search terms: choriocapillaris, choroid, quantification, biomarkers, diabetic retinopathy, age-related macular degeneration, choroidal blood flow, mean blur rate, flow deficit, optical coherence tomography, optical coherence tomography angiography, fluorescein angiography, indocyanine green angiography, OCTA, Doppler imaging, uveitis, choroiditis, white dot syndrome, tubercular serpiginous-like choroiditis, choroidal granuloma, pachychoroid, toxoplasmosis, central serous chorioretinopathy, multifocal choroiditis, choroidal neovascularization, choroidal thickness, choroidal vascularity index, choroidal vascular density, and choroidal blood supply. The search terms were used either independently or combined with choriocapillaris/choroid.

RESULTS

The imaging techniques which are used to qualitatively and quantitatively analyze choriocapillaris are described. The pathological alterations in the choriocapillaris in an array of conditions such as diabetes mellitus, age-related macular degeneration, pachychoroid spectrum of diseases, and inflammatory disorders have been comprehensively reviewed. The future directions in the study of choriocapillaris have also been discussed.

CONCLUSION

The development of imaging tools such as OCT and OCTA has dramatically improved the assessment of choriocapillaris in health and disease. The choriocapillaris can be delineated from the stromal choroid using the OCT and quantified by manual or automated methods. However, these techniques have inherent limitations due to the lack of an anatomical distinction between the choriocapillaris and the stromal choroid, which can be overcome with the use of predefined segmentation slabs on OCT and OCTA. These segmentation slabs help in standardizing the choriocapillaris imaging and obtain repeatable measurements in various conditions such as diabetic retinopathy, age-related macular degeneration, pachychoroid spectrum, and ocular inflammations. Additionally, Doppler imaging has also been effectively used to evaluate the choroidal blood flow and quantifying the choriocapillaris and establishing its role in the pathogenesis of various retinochoroidal diseases. As tremendous technological advancements such as wide-field and ultra-wide field imaging take place, there will be a significant improvement in the ease and accuracy of quantifying the choriocapillaris.

Comparison of Indocyanine Green Angiography and Swept-Source Wide-Field Optical Coherence Tomography Angiography in Posterior Uveitis

Purpose

To compare indocyanine green angiography (ICGA) and swept-source wide-field optical coherence tomography angiography (SS-OCTA) for the assessment of patients with posterior uveitis.

Method

SS-OCTA montage images of 5 x 12 x 12 mm or 2 x 15 x 9 mm, covering ~70-90 degree of the retina of consecutive patients with posterior uveitis were acquired. The choriocapillaries and choroidal slabs were compared to findings on ICGA.

Results

Sixty-eight eyes of 41 patients were included (mean age 47.2 ± 20.4 years; 58.5% female). In 23 (34%) lesions were visible on OCTA, but not discernable on ICGA. In turn, out of the 45 eyes with clearly discernable lesions on ICGA, 22 (49%) and 21 (47%) eyes showed no corresponding areas of flow deficit on OCTA in the CC and choroidal slab, respectively. Lesion size strongly correlated among ICGA and OCTA choriocapillaries- (CC) (r = 0.99, p ≤ 0.0001) and choroidal slabs (r = 0.99, p ≤ 0.0001), respectively. The mean lesion size on the late frames of ICGA (8.45 ± 5.47 mm2) was larger compared to the lesion size on OCTA CC scan (7.98 ± 5.47 mm2, p ≤ 0.0001) and choroidal scan (7.69 ± 5.10 mm2, p = 0.002), respectively. The lesion size on OCTA CC scan was significantly larger than on the OCTA choroidal scan (p ≤ 0.0001).

Conclusion

SS-wide field OCTA may be a promising tool to assess posterior uveitis patients and may replace ICGA to a certain extent in the future.

Artificial Intelligence and Imaging Processing in Optical Coherence Tomography and Digital Images in Uveitis

INTRODUCTION

Computer vision, understood as the area of science that trains computers to interpret digital images through both artificial intelligence (AI) and classical algorithms, has significantly advanced the analysis and interpretation of optical coherence tomography (OCT) in retina research. The aim of this review is to summarise the recent advances of computer vision in imaging processing in uveitis, with a particular focus in optical coherence tomography images.

MATERIAL AND METHODS

Literature review.

RESULTS

The development of computer vision to assist uveitis diagnosis and prognosis is still undergoing, but important efforts have been made in the field.

CONCLUSION

The automatising of image processing in uveitis could be fundamental to establish objective and standardised outcomes for future clinical trials. In addition, it could help to better understand the disease and its progression.

Retino-choroidal evaluation of the macular region in eyes with tubercular serpiginous-like choroiditis using swept-source optical coherence tomography angiography

AIM

To analyse the alterations in retino-choroidal angioarchitecture in eyes with active tubercular serpiginous-like choroiditis (TB-SLC) using swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

This prospective cross-sectional study enrolled 34 eyes diagnosed with TB-SLC and 34 age-matched healthy controls. Data acquisition with SS-OCTA using the PLEX Elite 9000 (Carl Zeiss Meditec Inc., Dublin, CA, USA) with a 6 × 6 mm pattern centered on the foveal center was done. Automated retinal vessel length density (VLD) and perfusion density (PD) and foveal avascular zone architecture were obtained from the ARI hub. Choroidal vascularity index (CVI) and choriocapillaris flow deficits (CCFD) were obtained using Image J.

RESULTS

Eyes with TB-SLC showed significantly reduced vessel indices in all retinal layers (P < 0.05), decreased CVI (P = 0.001) and increased CCFD (P = 0.001) as compared to healthy eyes. CCFD was increased significantly in the involved quadrants in eyes with TB-SLC when compared with the uninvolved quadrants and corresponding healthy quadrants in control subjects. CCFD showed a significant negative correlation with visual acuity (r = - 0.46, P = 0.006).

CONCLUSION

Eyes with TB-SLC manifest reduced VLD and PD, decreased CVI and increased CCFD. The CCFD alterations are non-uniform in these eyes, mainly located under the regions with disease activity.

A Novel Method of Quantifying the Choriocapillaris in Normal and Post-inflammatory Eyes

OBJECTIVE

To assess the reliability and validity of gray level co-occurrence matrices (GLCM) in the quantification of choriocapillaris and describe GLCM features in normal and eyes with resolved acute posterior multifocal placoid pigment epitheliopathy (APMPPE) and serpiginous choroiditis (SC).

METHODS

In this, multicenter, reliability, validity and comparative study; OCTA was performed on eyes with resolved APMPPE and SC and normal individuals. CC texture classification, low flow area measurements and GLCM feature extraction were performed.

RESULTS

A total of 13 normal, 8 APMPPE and 15 SC eyes were analyzed. All GLCM parameters demonstrated an excellent reliability. GLCM parameters were differently distributed across the three groups. Decision-tree based on the random forest predictive model provided an overall accuracy of 86% in classifying the three groups using GLCM features.

CONCLUSION

These data demonstrated an excellent reliability and validity of GLCM features in quantifying the choriocapillaris in healthy and diseased eyes.

Automated Quantification of Choriocapillaris Lesion Area in Patients With Posterior Uveitis

PURPOSE

To validate a custom algorithm for automated identification and quantification of clinically relevant inflammatory choriocapillaris (CC) lesions from en face swept-source optical coherence tomography (SS-OCTA) images.

DESIGN

Observational case series.

METHODS

Twenty eyes of 14 patients with posterior uveitis were imaged. The machine-generated en face OCTA CC slabs were exported to a computing platform, where a custom algorithm performed unsupervised lesion boundary delineation and area quantification. Lesions identified by the algorithm (AG) were compared to those identified by 2 masked human graders (HG1 and HG2), using the Sørensen-Dice coefficient (DSC) and intraclass correlation coefficient (ICC). Intragrader and intravisit reliability were determined by coefficient of variation (CV) and DSC.

RESULTS

The AG demonstrated excellent agreement with both HGs in determination of lesion area (HG1 vs AG ICC 0.92, 95% CI 0.81-0.97, HG2 vs AG ICC 0.91, 95% CI 0.78-0.97). The AG demonstrated good spatial overlap (DSC ≥0.70) with both HGs in 14 of 20 (70%) eyes and at least 1 HG in 16 of 20 (80%) eyes. Poor spatial overlap (DSC between 0.31 and 0.69) was associated with the presence of a choroidal neovascular membrane and low-contrast lesion boundaries. Intravisit repeatability for the AG was superior to both HGs (CV 2.6% vs >5%).

CONCLUSION

This custom algorithm demonstrated a high degree of agreement with HGs in identification of inflammatory CC lesions and outperformed HGs in reproducibility. Automated CC lesion delineation will support the development of objective and quantitative biomarker of disease activity in patients with posterior uveitis.

Serpiginous Choroiditis Complicated with Choroidal Neovascular Membrane Detected using Optical Coherence Tomography Angiography: A Case Series and Literature Review

Serpiginous choroiditis (SC) is a rare, chronic, recurrent, progressive disease of unknown origin. The inflammatory process of SC can disrupt Bruch’s membrane, allowing occasional choroidal vascular growth, leading to significant visual loss even in the healed stages of the disease. Optical coherence tomography angiography (OCTA) can help in the detection of choroidal neovascular membrane (CNV), leading to a definitive diagnosis and thereby guide the initiation of intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment. We report herein two cases of SC complicated with a CNV detected with OCTA and treated with a series of anti-VEGF injections.

Multimodal imaging supporting the pathophysiology of white dot syndromes

White dot syndromes (WDS) represent a heterogeneous group of inflammatory diseases, primarily affecting the outer retina, choriocapillaris and choroid. Recent advances in the field of ocular imaging and development of new technologies, including optical coherence tomography angiography (OCT-A), have allowed a better characterization of the morphology of these conditions. This review will analyse the WDS from an imaging-based perspective, providing a better understanding of the pathophysiology underlying these disorders.

Longitudinal study of serpiginous choroiditis and serpiginous like choroiditis using wide field OCT angiography

PURPOSE

To assess the ability of wide field Swept Source OCTA (SS-OCTA) imaging to detect morphological variations in Serpiginous Choroiditis (SC) and Serpiginous Like Choroiditis (SLC) in response to treatment and also analyze these findings quantitatively using Image J software.

METHODS

Retrospective observational case series of nine eyes with clinical diagnosis of active SC and SLC, who underwent SS-OCTA and fundus autofluorescence (FAF) imaging at baseline and each follow up visit till 6 months. Morphological analysis was done by two independent graders and quantitative analysis to measure the size and intensity of lesion was done using publicly available Image J software at baseline and each follow up visit.

DESIGN

Retrospective observational case series.

RESULTS

Using SS-OCTA, all the active lesions followed a characteristic healing pattern. Active lesions appear well defined hypo flow void patches and as healing progressed, lesion became more ill-defined and iso-hyper- intense. Significant increase in mean intensity of the lesion could be apparent after 1 and 6 month of treatment. There was reduction in the size of lesions during follow up however this difference was not statistically significant.

CONCLUSION

SS-OCTA could be a useful noninvasive tool to study the treatment response in SC/SLC both morphologically as well as quantitatively. Quantitative parameters need to be designed in further research studies to aid in uniform management and follow up of uveitis cases.

Multimodal imaging in infectious and noninfectious intermediate, posterior and panuveitis

PURPOSE OF REVIEW

Given the heterogeneity of uveitis, markers of inflammation vary from patient to patient. Multimodal imaging has proven itself to be critical for accurate evaluation for disease activity and treatment response in uveitis.

RECENT FINDINGS

Ultra-widefield (UWF) fluorescein angiography and autofluorescence (AF) as well as optical coherence tomography angiography (OCTA) have provided insights into disease pathogenesis and monitoring not previously appreciated. In addition to structural retinal imaging, OCT can be used to assess the choroid, the posterior cortical vitreous and the retinal vasculature in eyes with uveitis.

SUMMARY

Multimodal ocular imaging in eyes with uveitis is critical for disease diagnosis and assessing response to treatment. UWF fluorescein angiography can detect retinal vasculitis even in the absence of overt vascular sheathing. UWF AF can help detect more chorioretinal lesions than clinically visible. OCT can be used to assess the posterior cortical vitreous, retina, large retinal vessels and choroid in uveitis. The use of multimodal imaging will likely be needed to determine clinical trial endpoints in studies evaluating therapeutics for uveitis.

Evaluation of change in the vascular density of choriocapillaris on optical coherence tomography angiography in eyes with serpiginous choroiditis

Purpose:

Serpiginous choroiditis (SC) is primarily an inflammation of choriocapillaris leading to nonperfusion. A quantitative assessment of choriocapillaris perfusion can be done by measuring the flow-density by OCT-Angiography (OCTA). This study measures a change in the flow-density of choriocapillaris with the resolution of inflammation.

Methods:

The OCTA images of a choriocapillaris slab of 30 eyes with active SC were subjected to binarization and vessel density was measured at baseline and final visits and compared.

Results:

Upon comparing the vessel density of the affected areas by OCTA of choriocapillaris-slab at baseline and final visits, there was statistically significant (P < 0.0001) improvement after the resolution of inflammation. The vessel density of a demarcated normal area was significantly higher when compared to that of lesions at baseline (P < 0.0001) and final visit (P < 0.0001).

Conclusion:

OCTA is a useful tool to assess reduction in the inflammatory activity on treatment in SC. This study shows that with treatment the perfusion of choriocapillaris improves; however, it remains lower than normal.

LONGITUDINAL FOLLOW-UP OF TUBERCULAR SERPIGINOUS-LIKE CHOROIDITIS USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To analyze and describe serial follow-up of choriocapillaris alterations in tubercular serpiginouslike choroiditis (SLC) using optical coherence tomography angiography (OCTA) and to compare it with multimodal imaging.

METHODS

In this prospective cohort study, patients with active tubercular SLC underwent OCTA using Optovue RTVue XR Avanti and other imaging techniques including enhanced-depth imaging OCT (EDI-OCT) (Heidelberg Spectralis; Heidelberg Engineering, Heidelberg, Germany), fundus autofluorescence, fluorescein angiography, and indocyanine green angiography. Serial imaging was performed for a total follow-up of 3 months. Choriocapillaris alterations at the site of lesions were analyzed on OCTA imaging, and their mean lesion areas were calculated.

RESULTS

Twenty-six eyes (26 patients; 20 males; mean age: 32.68 ± 10.56 years) were included. Fourteen eyes had active multifocal lesions (n = 39), whereas 12 eyes had active placoid lesions (n = 12). At baseline, OCTA showed hyporeflective flow deficit lesions corresponding to the hypofluorescent lesions on indocyanine green angiography in all eyes. In the multifocal type of SLC, the mean lesion area decreased in all eyes compared with baseline, and lesions with a lesion area less than 0.1 mm2 on OCTA showed near-complete resolution with minimal choriocapillaris atrophy. In comparison, all eyes with a placoid type of SLC showed no significant reduction in the lesion area and showed extensive choriocapillaris atrophy.

CONCLUSION

Optical coherence tomography angiography has the unique ability to demonstrate pathological flow impairment at the level of choriocapillaris in active tubercular SLC. Serial OCTA analysis reveals that large tubercular SLC lesions result in choriocapillaris atrophy as the lesions heal, whereas smaller multifocal lesions show resolution of choriocapillaris hypoperfusion with minimal atrophy.

Choriocapillaris Assessment In Patients Under Mek-Inhibitor Therapy For Cutaneous Melanoma: An Optical Coherence Tomography Angiography Study

PURPOSE

The present study investigates by optical coherence tomography angiography (OCTA) the retinal capillary plexus and choriocapillaris flow voids and their possible correlation with MEKAR.

METHODS

34 eyes of 17 patients (61.5 years [30.4-77.4]) with stage IV cutaneous melanoma were included prospectively. All patients showed disease progression under treatment with Nivolumab/Ipilimumab and were subsequently treated with the MEK-inhibitor Trametinib 2 mg once daily. At the start and every 6 weeks during follow-up of 4 months, patients underwent a complete ophthalmologic exam, OCTA and when needed fluorescein angiography.

RESULTS

Statistical analysis was performed on 17 eyes of 9 patients. Eight patients were excluded due to missing OCTA images or due to drop-out because of decease or change of treatment. Comparing vessel area density (P = .625 and 0.681, respectively), vessel skeleton density (P = .996 and 0.766, respectively) of the superficial and deep capillary plexus, flow void number and total flow void area (mm² and %) (P = .495; 0.197 and 0.298, respectively) of choriocapillaris slab, before and after treatment, revealed no significant difference. The evolution of choriocapillaris flow void parameter did not significantly differ in patients, who developed MEKAR compared to patients who did not.

CONCLUSION

In patients receiving MEK-inhibitor with and without MEKAR, no significant different characteristics of the retinal capillary plexus and choriocapillaris were found. These data suggest that the development of MEKAR, has no correlation with vascular alteration.

Review of the Current Literature and Our Experience on the Value of OCT-angiography in White Dot Syndromes

PURPOSE

To describe the application of OCT-A in various posterior uveitis disorders in our experience and to compare it with the available literature.

METHODS

Eighteen eyes with the diagnoses of multifocal choroiditis (MFC), multifocal placoid pigment epitheliopathy (APMPPE), multiple evanescent white dot syndrome (MEWDS), tuberculous serpiginous-like choroiditis (SLC), serpiginous choroiditis (SC), and birdshot chorioretinopathy (BSCR) were studied.

RESULTS

We found flow void of the choriocapillaris in patients with APMPPE, SC, MFC, BSCR, and in SLC. In contrast, perfusion of the choriocapillaris seemed normal in patients with MEWDS.

CONCLUSIONS

We confirmed that OCT-A contributes new information on the physiopathology of white dot syndromes and inflammatory chorioretinopathies, notably on whether or not the choriocapillaris is involved. Comparing the OCT-A features allowed us to suggest that both APMPPE and SLC might be part of the same spectrum of inflammatory disease with primary involvement at the level of the choriocapillaris and secondary RPE damage.

Swept source OCTA reveals a link between choriocapillaris blood flow and vision loss in a case of tubercular serpiginous-like choroiditis

Optical coherence tomography angiography (OCTA) is a non-invasive technique that is useful in the diagnosis and management of patients with posterior uveitis. Here we report the use of swept source OCTA (SS-OCTA) in a patient with tuberculosis (TB) associated serpiginous like choroiditis (TB-SLC) that made a full visual recovery following treatment with ATT, local and systemic corticosteroids, and systemic immune modulation. By comparing en face images of choriocapillaris (CC) blood flow before and after treatment, we conclude that the patient's visual recovery was associated with resolution of extensive CC flow deficits. This case highlights the utility of SS-OCTA in the multimodal evaluation of patients with choroidal inflammation, and the potential for good visual recovery in patients treated for TB-SLC.

Placoid lesions of the retina: progress in multimodal imaging and clinical perspective

Placoid lesions of the retina may be secondary to a wide spectrum of acquired inflammatory conditions that have been reported as single entities with different presentation and clinical course. These conditions include acute posterior multifocal placoid pigment epitheliopathy, persistent placoid maculopathy, serpiginous choroiditis, serpiginous-like choroiditis, relentless placoid chorioretinitis and acute syphilitic posterior placoid chorioretinitis. In this article, we will group these conditions under the name of 'placoids'. The recognition of the specific condition may be challenging in clinical practice, often resulting in diagnostic and therapeutic delay. Given the complex nature of placoids and their similarities, a systematic approach including differentiating between infectious and non-infectious aetiologies increases the chance of reaching the correct diagnosis. Detailed history and comprehensive clinical examination are the first steps to formulate a diagnostic hypothesis that should be corroborated by multimodal imaging and appropriate investigations. The advent of multimodal imaging has made it possible to extensively study placoids and revealed a constellation of specific findings that may help clinicians in the diagnostic process. The treatment of the conditions other than syphilis is complex and sometimes challenging. Our article is aimed at giving an overview of the individual entities associated with placoids and discussing the differential diagnosis. A practical and systematic approach is then proposed.

Comparison of wide-field swept source optical coherence tomography angiography and fundus autofluorescence in tubercular serpiginous-like choroiditis

Purpose:

To evaluate the potential clinical utility of wide-field swept source optical coherence tomography angiography (SS-OCTA) using a prototype device compared to a wide-field fundus autofluorescence (FAF) for analysis of the disease activity in eyes with tubercular serpiginous-like choroiditis (TBSLC).

Methods:

Using a prototype SS-OCTA device (PLEX Elite, Carl Zeiss Meditec, Dublin, CA), 17 eyes of 12 consecutive patients with TBSLC were imaged and multiple 12 mm × 12 mm OCTA scans were captured, which were montaged to create wide-field montage OCTA images scans. A wide- FAF (Eidon, CenterVue, Padova, Italy) was performed in the same sitting. Two masked graders independently analyzed OCTA and FAF images for the presence of choroidal lesions, recorded the number of lesions identifiable, and provided a subjective grading for the activity of individual lesion, which were then compared.

Results:

The total number of lesions identified on FAF were 282 (posterior pole lesions, n = 129 and peripheral lesions n = 153) and on wide-field SS-OCTA were 230 (posterior pole lesions, n = 108 and peripheral lesions n = 122). Active choroidal lesions were comparable on the two machines (n = 28 on FAF and n = 28 on SS-OCTA, respectively); whereas numerous healed lesions were identified on FAF (n = 219) as compared to SS-OCTA (n = 170). There was good correlation among the devices for healed lesions (Pearson correlation, r = 0.82) and active lesions (r = 0.88).

Conclusion:

There was good correlation between FAF and wide-field SS-OCTA for detection of disease activity in TBSLC; however, FAF depicted greater number of healed lesions compared to wide-field SS-OCTA.

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.

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.

OCT Angiography and En Face OCT Reflectance Aid in Monitoring Subclinical Inflammation in Serpiginous Choroidopathy

Introduction. We present a case of serpiginous choroidopathy (SC) with novel OCTA and en face OCT reflectance findings which help identify subclinical disease progression. Case Presentation. En face OCT reflectance images demonstrated outer retinal tubules (ORT) at the serpiginous lesion margins of affected and unaffected retina on multimodal imaging. OCTA findings demonstrate variable dropout of choriocapillaris in “normal” retina beyond lesion borders which was not visible on standard imaging and which demonstrated a clear transition zone beyond the ORT. Discussion. This is the first report of choriocapillaris atrophy identified on OCTA not identified on traditional multimodal imaging in serpiginous choroidopathy. Damage to vasculature only visible with OCTA may help characterize the distribution of inflammation, aiding in monitoring of suppression not illustrated by traditional imaging and which may threaten the central macula. ORT in SC suggest death and reorganization of outer segments from dysfunction of the choriocapillaris and RPE, as well as serve to demarcate the area of chronic or old inflammation, supporting the hypothesis that the choriocapillaris is the primary site of inflammation in SC. Based on these findings, we recommend OCTA on all patients with serpiginous choroidopathy to monitor underlying state of inflammation and help determine immunosuppressive threshold.

Swept-source optical coherence tomography imaging of the retinochoroid and beyond

Introduction: Swept-source optical coherence tomography (SS-OCT) imaging has ushered in an era of rapid and high-resolution imaging of the retinochoroid that provides detailed patho-anatomy of various layers.Areas covered: In this detailed review, the technology of swept-source imaging including its principles and working has been discussed. The applications of SS-OCT in various conditions including age-related macular degeneration, diabetic retinopathy, pachychoroid spectrum of diseases, and inflammatory vitreoretinal conditions have been elaborated. For each disease, a brief review of literature along with the utility of SS-OCT and optical coherence tomography angiography has been provided with supporting figures. The advantages of SS-OCT over spectral-domain have been discussed if there is sufficient evidence in the literature. Finally, the review summarizes the technological advantages in this field of retinal imaging.Expert opinion: The introduction of SS-OCT in our clinics has added newer devices in our armamentarium that can provide high-quality images of the deep retina and choroid. These advances in medical devices can help in improving our knowledge relating to the pathophysiology of diseases and their evolution. In the near future, rapid and high-resolution imaging may provide real-time volumetric information of the whole retina and the choroid that can be readily used for patient care.

[White dot syndromes : Principles, diagnostics, and treatment]

The white dot syndromes include a group of diseases which are characterized by multiple yellowish-white foci in the outer retina, retinal pigment epithelium, and choroid. For clinicians and researchers alike they present significant diagnostic and therapeutic challenges. White dot syndromes include primary inflammatory choriocapillaropathies, such as acute posterior multifocal placoid pigment epitheliopathy (APMPPE)/acute multifocal ischemic choriocapillaropathy (AMIC), multiple evanescent white dot syndrome (MEWDS)/acute idiopathic blind spot enlargement (AIBSE), multifocal choroiditis (MFC), punctate inner choroidopathy (PIC), serpiginous choroiditis (SC), acute zonal occult outer retinopathy (AZOOR), and acute macular neuroretinopathy (AMN). Among the primary stromal choroiditis is birdshot retinochoroidopathy (BSRC); however, the pathogenesis of these disorders is largely unknown. Immunological reactions to previous viral infections with a genetic disposition seem to be a common denominator.

Optical coherence tomography angiography (OCTA) as a new diagnostic tool in uveitis

Background

The broad spectrum of uveitis disorders requires a multimodal imaging approach in the daily practice of an ophthalmologist. As inflammatory conditions, they have in common an alteration in leukocyte migration. In this context, optical coherence tomography angiography (OCTA) might be of great value for diagnosing or following up patients with these disorders. To date, OCTA has rather been used as an additional tool besides the well-established diagnostic imaging tools, but its complementary diagnostic features become increasingly relevant, to follow disease activity and treatment response and for the understanding of pathomechanisms of various uveitis types.

This review summarizes the possible applications of OCTA and its advantages and disadvantages as opposed to dye-based angiographies in uveitic diseases.

Main body

Hitherto gold standards in the diagnostic workup of posterior or intermediate uveitis have been angiography on a dye-based method, which is fluorescein or indocyanine green. It gives information about the status of the blood-retinal barrier and the retinal and choroidal vasculature by visualizing diffuse leakage as a state of inflammation or complications as an ischemia or choroidal neovascularization. As noninvasive methods, fundus autofluorescence depicts the status of metabolic activity of the retinal pigment epithelium and OCT or enhanced depth imaging OCT, respectively, as a depth-resolving imaging method can supply additional information.

OCTA as a non-invasive, depth-resolution imaging tool of retinal and choroidal vessels adds detailed qualitative and quantitative information of the status of retinal and choroidal vessels and bridges the gap between the mentioned conventional diagnostic tools used in uveitis.

It is important, though, to be aware of its limitations, such as its susceptibility to motion artifacts, limited comparability among different devices, and restricted contribution of information regarding the grade of disease activity.

Conclusion

OCTA as a non-invasive, depth-resolution imaging tool can give qualitative and quantitative information about the status of retinal and choroidal vessels, but also has certain limitations. Employing OCTA as a complementary rather than exclusive tool, it can give important additional information about the macro- and microvasculature under inflammatory circumstances. Thereby, it also contributes to the understanding of the pathophysiology of various uveitis entities.

Quantifying choriocapillaris flow deficits using global and localized thresholding methods: a correlation study

BACKGROUND

To investigate the correlation and agreement of two previously published choriocapillaris (CC) quantification methods using a normal database with swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

Normal adult subjects from all age groups imaged by SS-OCTA were used in this study. Each subject was imaged with 3 mm × 3 mm and 6 mm × 6 mm scan patterns centered on fovea, upon which en face CC images were generated by segmenting volumetric OCTA data. After signal compensation and removal of projection artifacts and noise, CC images were analyzed to identify flow deficits (FD) using two published methods. The first method utilized standard deviation from a young normal database (SD method) as the global thresholding while the second method utilized fuzzy C-means algorithm (FCM method) with local thresholding. Both methods segmented FDs from CC images and quantified FD density (FDD) and mean FD size (MFDS). In each 3 mm × 3 mm scan, three regions were quantified: a 1 mm circle (C1), a 1.5 mm rim (R1.5) and a 2.5 mm circle (C2.5). In each 6 mm × 6 mm scan, five regions were quantified: C1, R1.5, C2.5, a 2.5 mm rim (R2.5) and a 5 mm circle (C5). Spearman correlation and Bland-Altman plot analyses were conducted to compare the two methods.

RESULTS

Data obtained from 164 normal subjects (age: 56±19, 59% females) were used in this study. Strong correlations were observed between the two methods in all comparisons (r: 0.78-0.94, all P<0.0001). Overall MFDS provided higher or comparable correlation coefficients (r) compared to FDD. We have also observed stronger correlations in the central macula compared to parafoveal and perifoveal regions for both FDD and MFDS. In regions of C1, R1.5 and C2.5, 6 mm × 6 mm scans resulted in better agreement (smaller mean bias, similar or tighter limit of agreement) between the two methods for both FDD and MFDS compared to 3 mm × 3 mm scans.

CONCLUSIONS

There are strong correlations and satisfactory agreement between SD method and FCM method. SD method requires the reference to a normal database for CC quantification while FCM does not. Both methods could be used for the analysis of CC FDs in clinical settings depending on specific study designs such as the availability of a normal database.