Evolution of Choroidal Neovascularization due to Presumed Ocular Histoplasmosis Syndrome on Multimodal Imaging including Optical Coherence Tomography Angiography

Differentiation of Features of Inflammatory Neovascular Membrane Versus Active Posterior Uveitis by SS-OCTA

BACKGROUND AND OBJECTIVE

Neovascularization is a sight-threatening, uncommon complication of posterior uveitis that often goes undetected until persistent clinical findings appear, or in light of treatment failure. This could be attributed to the relative similarity of activity signs in inflammatory neovascular membranes (NVM) and active posterior uveitis. The purpose of the present study is to recognize imaging features that distinguish uveitic neovascularization from active uveitis using swept-source optical coherence tomography angiography (SS-OCTA).

PATIENTS AND METHODS

Cross-sectional study. Patients with posterior uveitis with visual acuity (VA) decrease and at least one of the following findings were assessed by SS-OCTA: retinal thickening, subretinal or intraretinal fluid, and retinal hyperreflective areas. The change of VA and imaging features after treatment with anti-vascular endothelial growth factor (VEGF) therapy were analyzed in cases with inflammatory NVM.

RESULTS

Forty-five eyes of 40 patients were evaluated. Twenty-four eyes (53.3%) showed signs of activity, of which eight (33.3%) presented inflammatory NVM. Imaging features that differentiate inflammatory neovascularization from active posterior uveitis included: vitreous cellularity (P = .003), outer retinal infiltration (P = .08), choroidal thickness (P = .003), posterior shadowing (P = .013), subretinal fluid (P = .04), and neovascular network (P ≤ .001). According to NVM characteristics by OCTA, multiple anastomoses and peripheral arcades were visualized at baseline in 85.7% of cases. Mean pre-operative best-corrected VA of inflammatory NVM was 20/150 (logMAR: 0.88 ± 0.60) with significant improvement to 20/40 (logMAR: 0.32 ± 0.22) after anti-VEGF treatment (P = .027).

CONCLUSIONS

SS-OCTA achieves the distinction of inflammatory NVM from active posterior uveitis through specific imaging features. Inflammatory neovascularization presents a suitable response after anti-VEGF therapy. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:129-137.].

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.

Comparison of choroidal neovascularization secondary to white dot syndromes and age-related macular degeneration by using optical coherence tomography angiography

Purpose

To characterize and compare choroidal neovascularization (CNV) secondary to white dot syndromes (WDS) and age-related macular degeneration (AMD) using optical coherence tomography angiography (OCT-A).

Methods

This is a cross-sectional study in which we imaged patients with CNV secondary to WDS and AMD with either the Zeiss Angioplex OCT-A or Optovue AngioVue OCT-A. Relevant demographic and clinical characteristics were collected and analyzed. CNV area and vessel density (VD) were measured by three independent graders, and linear regression analysis was subsequently performed.

Results

Three patients with multifocal choroiditis and panuveitis, one patient each with birdshot chorioretinopathy, presumed ocular histoplasmosis syndrome, and persistent placoid maculopathy, and eleven patients with AMD with sufficient image quality were included. CNV associated with WDS was significantly smaller than that secondary to AMD (0.56±0.32 vs 2.79±1.80 mm², β=-2.22, P=0.01), while no difference in VD was detected (0.46±0.09 vs 0.44±0.09, β=0.02, P=0.71).

Conclusion

CNV networks secondary to WDS appear to be smaller than those secondary to AMD but have similar VD. OCT-A is a powerful tool to investigate properties of CNV from various etiologies. Larger studies are needed for further characterization and understanding of CNV pathogenesis in inflammatory conditions.