Latest advances in white spot syndromes: New findings and interpretations

White spot syndromes (WSS) pose challenges in the field of ophthalmology, particularly in terms of accurate diagnosis and effective management. However, recent advancements in multimodal imaging (MMI) have significantly contributed to our understanding of WSS, allowing for improved characterization of these inflammatory chorioretinopathies. By employing various imaging modalities, including fundus fluorescein angiography, indocyanine green angiography, fundus autofluorescence, optical coherence tomography (OCT), ultra-widefield imaging, and OCT angiography, researchers and clinicians have gained valuable insights into the underlying pathophysiological changes and clinical progression of WSS. Furthermore, MMI has unveiled novel and atypical variants within the spectrum of WSS, expanding our knowledge in this field. Notably, the identification of secondary forms of WSS occurring concurrently with unrelated chorioretinal disorders has suggested a potential autoimmune mechanism underlying these conditions. The introduction of MMI has also facilitated a more comprehensive evaluation of previously ill-defined entities, such as acute zonal occult outer retinopathy, leading to improved diagnostic criteria and enhanced recognition of distinct features. This review paper provides a comprehensive overview of the latest advances and interpretations in WSS. By integrating MMI into the diagnosis and management of these conditions, this review aims to enhance patient outcomes and provide valuable insights into the complexities surrounding WSS.

Exploring Imaging Characteristics Associated With Disease Activity in Idiopathic Multifocal Choroiditis: A Multimodal Imaging Approach

PURPOSE

To identify characteristics on multimodal imaging (MMI) in idiopathic multifocal choroiditis (MFC) that can identify inflammatory activity and distinguish choroidal neovascularization (CNV) activity from inflammatory activity.

DESIGN

Prospective cohort study.

METHODS

MMI consisted of spectral-domain optical coherence tomography (angiography) (SD-OCT(A)), fundus autofluorescence, fundus photography, infrared imaging, fluorescein angiography (FA), and indocyanine green angiography (ICGA). MMI characteristics obtained during active and inactive disease were compared within the same lesion. Secondly, MMI characteristics were compared between active inflammatory lesions with and without CNV activity.

RESULTS

Fifty patients (110 lesions) were included. In 96 lesions without CNV activity, the mean focal choroidal thickness was increased during the active disease (205 µm) compared to the inactive disease (180 µm) (P ≤ .001). Lesions with inflammatory activity typically demonstrated moderately reflective material located in the sub-retinal pigment epithelium (RPE) and/or in the outer retina with disruption of the ellipsoid zone. During the inactive stage of the disease, the material disappeared or became hyperreflective and indistinguishable from the RPE. During the active stage of the disease, the area of hypoperfusion in the choriocapillaris significantly increased as visualized on both ICGA and SD-OCTA. CNV activity in 14 lesions was associated with subretinal material with a mixed reflectivity and hypotransmission of light to the choroid on SD-OCT and leakage on FA. SD-OCTA identified vascular structures in all active CNV lesions and in 24% of lesions without CNV activity (showing old, quiescent CNV membranes).

CONCLUSION

Inflammatory activity in idiopathic MFC was associated with several MMI characteristics, including focally increased choroidal thickness. These characteristics can guide clinicians in the challenging process of the evaluation of disease activity in idiopathic MFC patients.

Optical Coherence Tomography Angiography (OCT-A) in Uveitis: A Literature Review and a Reassessment of Its Real Role

BACKGROUND

The global and precise follow-up of uveitis has become possible with the availability of dual fluorescein (FA) and indocyanine green angiography (ICGA) since the mid-1990s. Progressively, additional non-invasive imaging methods have emerged, bringing value-added precision to the imaging appraisal of uveitis, including, among others, optical coherence tomography (OCT), enhanced-depth imaging OCT (EDI-OCT) and blue light fundus autofluorescence (BAF). More recently, another complementary imaging method, OCT-angiography (OCT-A), further allowed retinal and choroidal circulation to be imaged without the need for dye injection.

PURPOSE

The purpose of this review was aimed at examining the evidence in published reports indicating whether OCT-A could possibly replace dye angiographic methods, as well as the real practical impact of OCT-A.

METHODS

A literature search in the PubMed database was performed using the terms OCT-angiography and uveitis, OCTA and uveitis and OCT-A and uveitis. Case reports were excluded. Articles were classified into technical reports, research reports and reviews. Articles in the two latter categories were analyzed in a more detailed, individual fashion. Special attention was paid to whether there were arguments in favor of an exclusive rather than complementary use of OCT-A. Furthermore, a synthesis of the main practical applications of OCT-A in the management of uveitis was attempted.

RESULTS

Between 2016 (the year of the first articles) and 2022, 144 articles containing the search terms were identified. After excluding case report articles, 114 articles were retained: 4 in 2016, 17 in 2017, 14 in 2018, 21 in 2019, 14 in 2020, 18 in 2021 and 26 in 2022. Seven articles contained technical information or consensus-based terminology. Ninety-two articles could be considered as clinical research articles. Of those, only two hinted in their conclusions that OCT-A could hypothetically replace dye methods. The terms mostly used to qualify the contribution of the articles in this group were "complementary to dye methods", "adjunct", "supplementing" and other similar terms. Fifteen articles were reviews, none of which hinted that OCT-A could replace dye methods. The situations where OCT-A represented a significant practical contribution to the practical appraisal of uveitis were identified.

CONCLUSION

To date, no evidence was found in the literature that OCT-A can replace the classic dye methods; however, it can complement them. Promoting the possibility that non-invasive OCT-A can substitute the invasive dye methods is deleterious, giving the elusive impression that dye methods are no longer inevitable for evaluating uveitis patients. Nevertheless, OCT-A is a precious tool in uveitis research.

Effects of Induced Astigmatism on Spectral Domain-OCT Angiography Quantitative Metrics

PURPOSE

To analyze the effect of induced astigmatism on en-face spectral-domain optical coherence tomography angiography quantitative metrics.

DESIGN

Prospective crossover study.

METHODS

Normal eyes without astigmatism and with 0.75, 1.75, and 2.75 diopters (D) of with-the-rule (WTR) astigmatism were imaged using a 3 × 3-mm scan pattern SD-OCTA CIRRUS 5000 HD-OCT with AngioPlex (Carl Zeiss Meditec, Dublin, CA, USA). Quantitative parameters, including foveal avascular zone metrics, parafoveal vessel length density (VD), and perfusion density (PD) were corrected for magnification secondary to axial length and analyzed. Univariate linear regressions were performed within each eye to correlate quantitative metrics to the level of an induced astigmatic cylinder.

RESULTS

Fifteen eyes from 15 patients were imaged. Every 1-D increase in induced WTR astigmatism was associated with a statistically significant decrease in VD and PD within all Early Treatment Diabetic Retinopathy Study inner ring quadrants; however, especially more so nasally (VD: 0.63; P < .001; PD: 0.0089; P = .001). For every 1-D increase in induced astigmatism, the resulting decrease in the inner ring superior quadrant was 12% greater for VD and 16% greater for PD versus that in the inferior quadrant. The resulting decrease in the inner ring nasal quadrant was 40% greater for VD and 48% greater for PD versus that in the temporal quadrant.

CONCLUSIONS

Increasing levels of induced WTR astigmatism correlated with globally diminishing VD and PD, was more symmetrical for vertical than horizontal quadrants, and was most pronounced nasally. This may be due to a high prevalence of horizontally oriented vessels nasally and the horizontal optical defocus induced by WTR astigmatism.

[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.

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.

Quantitative optical coherence tomography angiography biomarkers for neovascular age-related macular degeneration in remission

Purpose

To characterize quantitative optical coherence tomography angiography (OCT-A) parameters in active neovascular age-related macular degeneration (nAMD) patients under treatment and remission nAMD patients.

Design

Retrospective, cross-sectional study.

Participants

One hundred and four patients of whom 72 were in Group 1 (active nAMD) and 32 in Group 2 (remission nAMD) based on SD-OCT (Spectral Domain OCT) qualitative morphology.

Methods

This study was conducted at the Centre Ophtalmologique de l’Odeon between June 2016 and December 2017. Eyes were analyzed using SD-OCT and high-speed (100 000 A-scans/second) 1050-nm wavelength swept-source OCT-A. Speckle noise removal and choroidal neovascularization (CNV) blood flow delineation were automatically performed. Quantitative parameters analyzed included blood flow area (Area), vessel density, fractal dimension (FD) and lacunarity. OCT-A image algorithms and graphical user interfaces were built as a unified tool in Matlab coding language. Generalized Additive Models were used to study the association between OCT-A parameters and nAMD remission on structural OCT. The models’ performance was assessed by the Akaike Information Criterion (AIC), Brier Score and by the area under the receiver operating characteristic curve (AUC). A p value of ≤ 0.05 was considered as statistically significant.

Results

Area, vessel density and FD were different (p<0.001) in the two groups. Regarding the association with CNV activity, Area alone had the highest AUC (AUC = 0.85; 95%CI: 0.77–0.93) followed by FD (AUC = 0.80; 95%CI: 0.71–0.88). Again, Area obtained the best values followed by FD in the AIC and Brier Score evaluations. The multivariate model that included both these variables attained the best performance considering all assessment criteria.

Conclusions

Blood flow characteristics on OCT-A may be associated with exudative signs on structural OCT. In the future, analyses of OCT-A quantitative parameters could potentially help evaluate CNV activity status and to develop personalized treatment and follow-up cycles.