MICROVASCULAR FLOW ABNORMALITIES ASSOCIATED WITH RETINAL VASCULITIS: A Potential of Mechanism of Retinal Injury

Defining Retinal Vasculitis

PURPOSE

To assess the validity of retinal vasculitis as the preferred diagnostic term for multiple conditions.

DESIGN

Perspective METHODS: Expert opinion and review of literature focused on the current nosology and pathology of retinal vasculitis. Interpretation of the subset of intraocular inflammation named retinal vasculitis based on fundamental knowledge of the blood-retinal barrier, the neurovascular unit and pathological and functional responses to a variety of stimuli. Correlation with multimodal imaging and known mechanisms of immunologically mediated disease.

RESULTS

A search of Medline in early 2024 for the phrase "retinal vasculitis" resulted in 2041 citations encompassing immunologic, genetic, neoplastic, infectious, drug- and ischemia-related disorders. Classification schemes and angiographic grading systems are descriptive and do not address pathologic mechanisms adequately, in part due to lack of histologic confirmation. Although OCT angiography holds promise for better imaging of retinal vascular changes, it does not reveal the key feature of leakage and only partially improves understanding of pathophysiology. Diagnosing catastrophic retinal vascular occlusion after intravitreal injections as a retinal vasculitis is the most recent example of speculative application of the term to complex and rare disorders.

CONCLUSIONS

Retinal vasculitis is a diagnostic term that is over-used and imprecise. Revised nosology should limit the term to primary inflammation of the retinal vasculature itself that results in opening of the blood-retinal barrier with or without retinal vascular occlusions. Pending new histologic or mechanistic evidence, the provisional term of retinal vascular inflammation or retinal vasculopathy should be used for leakage or occlusion occurring in the context of intraocular inflammation.

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.

RECONSTITUTION OF THE CHORIOCAPILLARIS IN ACUTE POSTERIOR MULTIFOCAL PLACOID PIGMENT EPITHELIOPATHY

PURPOSE

The purpose of this study was to describe findings derived from extensions of optical coherence tomography, including volume rendering and frame-averaged optical coherence tomography angiography (OCT-A), in a case of acute posterior multifocal placoid pigment epitheliopathy (APMPPE).

METHODS

This is a case report of a patient with APMPPE imaged during the acute and convalescent stages.

RESULTS

A 20-year-old man presented with an acute change in vision. He had multiple yellow-white placoid lesions at the level of the retinal pigment epithelium in the macula and nasal to the optic nerve in both eyes. Within 2 weeks, his visual acuity worsened to 20/80 and 20/400 in the right and left eyes, respectively. Spectral domain OCT showed focal defects in the ellipsoid and retinal pigment epithelium layers. Volume-rendering OCT-A showed inflammatory cells in the outer nuclear layer above the APMPPE lesion. Frame-averaged OCT-A revealed significant loss of capillary flow signal within capillary segments of the choriocapillaris. Ten weeks after presentation, there was resolution of the placoid changes, discontinuance of the inflammatory infiltrate in the outer nuclear layer, and significant reconstitution of flow in the choriocapillaris. The visual acuity was 20/20 in both eyes.

CONCLUSION

Novel volume-rendered and frame-averaged OCT-A images in a patient with APMPPE allowed detection of inflammatory cell infiltrate in the outer nuclear layer and reversible capillary segment nonperfusion of associated APMPPE lesions. The findings suggest short-term insults to choriocapillaris function may be reversible and can be tracked with modern imaging techniques.

Subclinical alterations in retinal layers and microvascular structures with OCTA in ANCA-associated vasculitides

PURPOSE

Using OCTA, investigate the capillary network and retinal layers in granulomatosis with ANCA associated vasculitis (AAV) patients who did not manifest apparent ocular involvement and compare the findings with healthy subjects.

METHOD

The present study, which is designed as a prospective and case-control study, includes 22 AAV patients and 35 control participants. OCTA parameters were noted.

RESULTS

In most of the regions, AMT, RNFL and GC-IPL thicknesses were significantly lower in the AAV group than in the control group. While the vascular indices were lower in the AAV group, except for the center 1 mm region, the FAZ parameters were similar between the two groups.

CONCLUSION

In AAV patients, subclinical changes in the retinal layers and superficial vascular plexus have been shown. In the future maybe a non-invasive method such as OCTA will become available in scoring systems for prognosis determination in AAV.

Ocular microvascular alteration in Sjögren syndrome

BACKGROUND

Sjögren syndrome (SjS) is a systemic disease affecting exocrine, including ocular lacrimal, glands. It is uncertain whether ocular microvascular alterations are associated with this disease. In this study, we evaluated retinal and conjunctival microvascular changes in SjS patients using optical coherence tomography angiography (OCTA).

METHODS

Twelve SjS patients (24 eyes) and 12 normal controls (24 eyes) were recruited to this study. Three-dimensional conjunctival and retinal OCTA images of each eye were captured and microvascular density was calculated. Each image was analyzed by retinal area based on the early treatment of diabetic retinopathy study method (R, S, L, and I) hemisphere segmentation method (SR, SL, IL, and IR); and central wheel division method (C1-C6). Correlation analyses were used to look for associations between retinal and conjunctival microvascular densities.

RESULTS

Superficial and deep retinal layer microvascular density was decreased in SjS patients compared with normal controls (P<0.05). This significant difference was found in both superficial and deep layers in S, L, SL, IL and C1-C3 regions, and additionally in the I and SR regions in the superficial layer. Conversely, in the conjunctiva microvascular density was higher in SjS patients than in controls. In SjS patients, a significant negative correlation was found between conjunctival and both superficial (r=-0.641; P=0.025) and deep (r=-0.958; P<0.0001) microvascular densities.

CONCLUSIONS

The changed microvascular densities measured in deep and superficial retinal layers and in the conjunctiva demonstrate that OCTA is a promising method in differentiating the eyes from those with SjS.

Recent advances in wide field and ultrawide field optical coherence tomography angiography in retinochoroidal pathologies

Introduction: With the advent of wide field (WF) and ultra-wide field (UWF) imaging in color fundus photography and fluorescein angiography (FA), the importance of an expanded field-of-view (FOV) has been illustrated for early detection of several chorioretinal disorders. The need to bring similar utility to optical coherence tomography angiography (OCTA) is imperative.Areas covered: For this review, we explored all research items with WF or UWF on Pubmed Central and Google Scholar. Software-based methods included algorithms for motion correction, artifact reduction, image pre-processing, post-processing and montage protocols while hardware methods included swept-source OCTA, faster scanning sources, hardware-based motion tracking and image registration, scanning sources with faster speeds and lower resolution. For various disorders such as diabetic retinopathy, uveitis, vascular disorders, among others, the increased FOV showed demonstrably increased detection rates and diagnostic yield.Expert opinion: Increased FOV in OCTA imaging is a meaningful and impactful step in ophthalmic imaging. Overcoming the hardware-based limitations can potentially yield higher FOV without loss of important details. In addition to improvements in the hardware and available equipment, better software tools and image processing algorithms may greatly enhance the utility of UWF OCTA in care of patients with various retinochoroidal diseases.

Multimodal imaging in pediatric uveitis

Pediatric uveitis accounts for up to 10% of all uveitis cases, so special attention must be paid to ensure early diagnosis as well as treatment and follow-up of these young patients in order to decrease the risk of possible ocular complications and consequently vision loss. Multimodal imaging has been an effective and important adjunct in the diagnoses and management of uveitis, especially in children. Reviewed here are the currently utilized modalities, advances, as well as their applications in juvenile idiopathic arthritis-associated uveitis, pars planitis, retinal vasculitis, tubulointerstitial nephritis and uveitis syndrome, Behçet disease, Blau syndrome, and Vogt-Koyanagi-Harada syndrome.

Clinical and Optical Coherence Tomography Angiographic Features in Patients with Postcataract Stenotrophomonas maltophilia Endophthalmitis

Purpose

To report the clinical presentations and optical coherence tomography (OCT) angiographic features of patients with postcataract surgery endophthalmitis due to Stenotrophomonas maltophilia. Methods. A retrospective observational study of 4 patients who developed S. maltophilia endophthalmitis after cataract surgery. Pars plana vitrectomy (PPV) was performed to control the infection. Patients were followed up for six months. Complete ophthalmological examination results were collected before and after PPV.

Results

Patients' response to PPV therapy was excellent and the infection was cured in all cases. OCTA showed that, at the one-month follow-up, the vascular density (VD) and perfusion density (PD) in the superficial capillary plexus (SCP) were significantly lower than those in healthy collateral eyes. As time went on, the SCP-VD and SCP-PD values gradually improved.

Conclusions

With early PPV, the infection caused by S. maltophilia can be cured. OCTA provides a quantitative noninvasive assessment to evaluate the severity and prognosis of patients with S. maltophilia endophthalmitis.

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.

Evaluation of vascular changes in intermediate uveitis and retinal vasculitis using swept-source wide-field optical coherence tomography angiography

Purpose

To evaluate vascular changes in patients with intermediate uveitis with or without retinal vasculitis using swept-source wide-field optical coherence tomography angiography (OCTA).

Methods

This is a prospective cross-sectional study. Consecutive patients with intermediate uveitis were evaluated using wide-field OCTA. Wide-field OCTA and en-face OCT images were analysed for the presence of capillary non-perfusion and reduced perfusion, disruption of ellipsoid zone, and abnormalities on en-face wide-field retinal thickness maps, respectively, and compared with fluorescein angiography (FA) findings in a subcohort.

Results

164 eyes of 88 patients with intermediate uveitis were included. Areas of capillary non-perfusion and reduced perfusion were more frequently observed in the choroidal OCTA slab (33.3% and 49.4%), choriocapillaris (CC; 31.4% and 48%) and deep capillary plexus (DCP; 9.6% and 34.6%) than in the superficial capillary plexus (SCP; 5% and 26.3%), respectively. Intermediate uveitis with vasculitis presented more frequently with non-perfusion and hypoperfusion in the DCP (p=0.003 and p=0.05, respectively) and SCP (p=0.007 and p=0.005, respectively) than intermediate uveitis without vasculitis. Peripheral capillary leakage on FA correlated with the presence of perivascular, macular and generalised thickening on en-face wide-field thickness maps (p=0.007). Ischaemia on FA was significantly associated with non-perfusion on wide-field OCTA in SCP and DCP (p=0.019 and p=0.027, respectively).

Conclusion

Changes in the choroid, CC and DCP are more frequently found than in the SCP on wide-field OCTA in intermediate uveitis. While wide-field OCTA is a reliable tool to detect capillary non-perfusion in intermediate uveitis, it was not helpful in determining disease activity.

Trial registration number

NCT02811536.

Optical coherence tomography angiography

Optical coherence tomography (OCT) was one of the biggest advances in ophthalmic imaging. Building on that platform, OCT angiography (OCTA) provides depth resolved images of blood flow in the retina and choroid with levels of detail far exceeding that obtained with older forms of imaging. This new modality is challenging because of the need for new equipment and processing techniques, current limitations of imaging capability, and rapid advancements in both imaging and in our understanding of the imaging and applicable pathophysiology of the retina and choroid. These factors lead to a steep learning curve, even for those with a working understanding dye-based ocular angiography. All for a method of imaging that is a little more than 10 years old. This review begins with a historical account of the development of OCTA, and the methods used in OCTA, including signal processing, image generation, and display techniques. This forms the basis to understand what OCTA images show as well as how image artifacts arise. The anatomy and imaging of specific vascular layers of the eye are reviewed. The integration of OCTA in multimodal imaging in the evaluation of retinal vascular occlusive diseases, diabetic retinopathy, uveitis, inherited diseases, age-related macular degeneration, and disorders of the optic nerve is presented. OCTA is an exciting, disruptive technology. Its use is rapidly expanding in clinical practice as well as for research into the pathophysiology of diseases of the posterior pole.

New imaging techniques in retinal vasculitis

The term retinal vasculitis (RV) encompasses a heterogeneous group of sight-threatening conditions that are included in the intraocular inflammatory diseases that affect the posterior segment of the eye. Based on the nature of the inflammatory process, RV are classified into predominantly inflammatory or ischaemic (occlusive RV). The diagnosis is clinical and the aetiology can be infectious or non-infectious (immune-mediated). RV can be an isolated ocular syndrome or be associated with a systemic disease, of which they can represent the first manifestation. New retinal imaging techniques such as ultra-wide field fluorescein angiography and optical coherence tomography angiography will help us classify the RV and aid the diagnostic process, which can be challenging and require a multidisciplinary approach. Therefore, clinical knowledge of RV is essential for prompt diagnosis and to establish the appropriate treatment.