Relevance of wide-field autofluorescence imaging in Birdshot retinochoroidopathy: descriptive analysis of 76 eyes

Stepwise approach for fundus imaging in the diagnosis and management of posterior uveitis

An array of retinochoroid imaging modalities aid in comprehensive evaluation of the immunopathological changes in the retina and choroid, forming the core component for the diagnosis and management of inflammatory disorders such as uveitis. The recent technological breakthroughs have led to the development of imaging platforms that can evaluate the layers of retina and choroid and the structural and functional alteration in these tissues. Ophthalmologists heavily rely on imaging modalities such as dye-based angiographies (fluorescein angiography and indocyanine green angiography), optical coherence tomography, fundus autofluorescence, as well as dye-less angiography such as optical coherence tomography angiograph,y for establishing a precise diagnosis and understanding the pathophysiology of the diseases. Furthermore, these tools are now being deployed with a 'multimodal' approach for swift and accurate diagnosis. In this comprehensive review, we outline the imaging platforms used for evaluation of posterior uveitis and discuss the organized, algorithmic approach for the assessment of the disorders. Additionally, we provide an insight into disease-specific characteristic pathological changes and the established strategies to rule out disorders with overlapping features on imaging.

Birdshot Chorioretinopathy: A Review

Birdshot chorioretinopathy (BSCR) is a bilateral chronic inflammation of the eye with no extraocular manifestations. BSCR affects middle-aged individuals from European descent and is strongly associated with the human leucocyte antigen (HLA)-A29 allele. The immune mechanisms involved are not fully understood, but recent advances have shown the role of Endoplasmic Reticulum Aminopeptidase 2 (ERAP2) in disease pathogenesis. Multimodal imaging, including fluorescein angiography, indocyanine angiography, fundus autofluorescence, and optical coherence tomography, are useful in confirming the diagnosis and monitoring disease activity. Visual field testing is also important to assess the disease progression. To date, there is no consensus for optimal treatment regimen and duration. Local and systemic corticosteroids can be used for short periods, but immunosuppressive or biological therapies are usually needed for the long-term management of the disease. Here, we will review publications focused on birdshot chorioretinopathy to give an update on the pathophysiology, the multimodal imaging, and the treatment of the disease.

HLA-A29 Birdshot Retinochoroiditis in Its 5th Decade: Selected Glimpses into the Intellectual Meanderings and Progresses in the Knowledge of a Long-Time Misunderstood Disease

The appraisal of HLA-A29 birdshot retinochoroiditis (BRC) was fraught with pitfalls and misunderstandings. Progress in investigational methods has led to better knowledge and management of the disease. Our aim was to assess some of the steps that have led to better characterisation of the clinical entity of BRC. We performed a literature search analysing the relevant progress in disease origin, investigational and imaging methods, clinicopathology and classification, diagnostic criteria and management. Following developments were judged essential in the better appraisal and understanding of the disease: (1) new immunopathological hypotheses regarding the role of endoplasmic reticulum peptidases, (2) the essential importance of HLA testing, (3) relevant imaging modalities among which indocyanine green angiography is crucial, (4) diagnostic criteria that allow early diagnosis and (5) need of an early prolonged, as well as aggressive treatment combining more than one immunosuppressive agent. Based on these findings it is now possible to better define BRC, an indolent however severe disease, unlike thought before, involving the choroidal stroma and the retina independently and concomitantly that can be diagnosed early thanks to indocyanine green angiography and should be treated early and relentlessly.

[Anatomic-functional correlations in birdshot chorioretinopathy: An observational single-center prospective study]

INTRODUCTION

The purpose of this study was to identify anatomic-functional correlations in patients with Birdshot chorioretinopathy in order to better understand the mechanisms of visual loss.

MATERIALS AND METHODS

We conducted a single-center observational prospective study at the Nantes University Medical Center including all patients followed for Birdshot chorioretinopathy between January 2019 and July 2019. The parameters studied were visual acuity, microperimetry, standard automated perimetry, SD-OCT, EDI-OCT, OCT-A, RNFL-OCT, wide-field fundus photographs, and fluorescein and ICG angiography.

RESULTS

Forty-four eyes were studied. A significant correlation was found between visual acuity and retinal thickness (P=0.002, r=0.44), but not choroidal thickness (P=0.16). A significant correlation was also observed between retinal sensitivity and total macular thickness (P<0.001, r=0.68) as well as inner retinal thickness (P<0.001, r=0.65), while the correlation was weaker with choroidal thickness (P=0.03, r=0.32). There was a weak correlation between retinal sensitivity and superficial capillary density (P=0.02, r=0.42) as well as deep capillary density (P=0.02, r=0.41). The peripheral hypo-autofluorescent zones correspond to the visual field defects, but these defects are larger than the hypo-autofluorescent zones. Patients with paracentral or peripheral field defects had a history of vasculitis more often than hypo-ICG spots.

DISCUSSION

We found significant correlations between functional parameters such as visual acuity and retinal sensitivity and retinal anatomic parameters, particularly the inner retina, while there was no correlation shown with choroidal anatomic parameters.

CONCLUSION

The main results of our study suggest a retinal rather than choroidal origin of the degradation of visual function in birdshot chorioretinopathy.

Association of Fundus Autofluorescence Findings and Outer Retinal Lesions on Optical Coherence Tomography With Visual Acuity in Birdshot Chorioretinopathy

Purpose

This article investigates the optical coherence tomography (OCT) and fundus autofluorescence imaging findings in birdshot chorioretinopathy (BSCR) and their association with visual acuity (VA).

Methods

In a retrospective, cross-sectional study, we evaluated OCT images for changes in retinal structure including cystoid macular edema (CME), epiretinal membrane, and outer retinal lesions. We assessed autofluorescence images for hypoautofluorescent and hyperautofluorescent changes and noted the distribution of the lesions. Demographic data and VA at the time of imaging were also collected. Associations between OCT and autofluorescence findings and logarithm of the minimum angle of resolution VA were tested using linear regression.

Results

We conducted a chart review of 80 eyes from 40 patients with BSCR. Outer retinal lesions were found on OCT in 28 of 80 eyes (35%) and disruption of the outer segment ellipsoid zone (EZ) occurred in 23 eyes (28.7%). Macular hypoautofluorescent lesions were more common than hyperautofluorescent lesions, present in 58.8% and 13% of eyes, respectively. The presence of outer retinal lesions on OCT was significantly associated with reduced VA (P = .006) as was EZ disruption (P = .003). These associations remained significant after accounting for the presence of macular edema. There was a trend toward association of macular hypoautofluorescent lesions with decreased vision, although it was not statistically significant (P = .17).

Conclusions

The association of outer retinal lesions with decreased VA suggests a mechanism of central vision loss that is distinct from CME and may provide an additional objective finding to monitor disease activity in BSCR patients.

Five-Year Trends in Multifocal Electroretinogram for Patients With Birdshot Chorioretinopathy

PURPOSE

The aim of this study is to investigate temporal trends in multifocal ERG (mfERG) parameters and analyze their relationships with anatomic and functional markers in patients with birdshot chorioretinopathy (BSCR).

DESIGN

Prospective observational case series.

METHODS

Sixteen BSCR patients were include and underwent 2 standardized follow-up (FU) visits within 5 years following a baseline examination, including mfERG, visual acuity (VA), visual field (VF), Lanthony desaturated panel D-15 test for color vision, quality of life (QoL), fluorescein and indocyanine green angiography, and optical coherence tomography (OCT).

RESULTS

A significant trend toward a decrease in absolute N1 amplitude values was observed over the follow-up period (P < .001) while N1 implicit time remained unchanged. In contrast, P1 amplitude decreased (P < .001) and P1 implicit time increased (P < .001) over the same period. No significant temporal change was found for VA, color vision score, foveal threshold, mean deviation of VF, and QoL. After adjusting for time to FU, increasing N1 and P1 IT were both associated with decreasing values of logMAR, foveal threshold, and QoL and with increasing color vision score and mean deviation of VF. A significant relationship was observed between decreasing P1 amplitude values and increasing mean deviation of VF. Lower absolute values of N1 amplitude were associated with venous vasculitis, whereas lower P1 amplitude values correlated with alteration of the outer retina in OCT.

CONCLUSIONS

Progressive deterioration in mfERG during a 5-year period is detected in BSCR, whereas classical functional test results were unchanged. This study suggests a better sensitivity of mfERG in monitoring the retinal function of BSCR patients.

The clinical relevance of visualising the peripheral retina

Recent developments in imaging technologies now allow the documentation, qualitative and quantitative evaluation of peripheral retinal lesions. As wide field retinal imaging, capturing both the central and peripheral retina up to 200° eccentricity, is becoming readily available the question is: what is it that we gain by imaging the periphery? Based on accumulating evidence it is clear that findings in the periphery do not always associate to those observed in the posterior pole. However, the newly acquired information may provide useful clues to previously unrecognised disease features and may facilitate more accurate disease prognostication. In this review, we explore the anatomy and physiology of the peripheral retina, focusing on how it differs from the posterior pole, recount the history of peripheral retinal imaging, describe various peripheral retinal lesions and evaluate the overall relevance of peripheral retinal findings to different diseases.

Analysis of autofluorescence pattern in birdshot chorioretinopathy

PURPOSE

To characterize and correlate the different patterns of fundus autofluorescence (FAF) in patients with birdshot chorioretinopathy (BSCR), with functional and anatomical parameters.

METHODS

Twenty-one BSCR patients were prospectively studied in 2013 and 2014. Each patient underwent visual acuity (VA) and visual field (SITA standard 30.2) testing as well as fluorescein and indocyanine green angiography, spectral-domain optical coherence tomography (SD-OCT) B scan, enhanced depth imaging (EDI), and fundus autofluorescence (FAF) imaging. The disease was classified as active, chronic, or quiescent.

RESULTS

The patients' mean age was 60.3 ± 9.2 years and 60% were female. Disease duration was 5.7 ± 3.7 years. Autofluorescence imaging showed punctiform hyper-FAF spots in 23 out of the 29 eyes (79%), which was significantly associated with a greater visual field mean deviation (-7 ± 7 versus -3 ± 2 dB, p = 0.04). Hypo-FAF was defined as peripapillary (n = 25; 86.2%), macular (n = 10; 34.5%), lichenoid (n = 17; 58.6%), and/or diffuse (n = 13; 44.8%). Lichenoid hypo-FAF was significantly associated with worse VA (0.18 ± 0.24 vs. 0.05 ± 0.07 LogMAR, p = 0.04). Macular hypo-FAF was associated with a history of macular edema (62.5%; p = 0.06). Diffuse hypo-FAF was observed more frequently (p = 0.01) in chronic disease (66.7%) than in active (0%) or quiescent disease (27.3%).

CONCLUSIONS

Autofluorescence analysis in BRSC patients contributes to evaluating disease activity and could be useful to guide follow-up and treatment.

Assessment of retinal vascular calibres as a biomarker of disease activity in birdshot chorioretinopathy

PURPOSE

Birdshot chorioretinopathy (BCR) is a potentially blinding ocular disorder involving the retinal vasculature and choroid without any systemic manifestations. The objective of the study was to describe vascular calibre changes in BCR and analyse the possibility of this optical biomarker for staging and monitoring disease activity in BCR.

METHODS

This retrospective case-control study at a tertiary referral eye centre in the UK included 33 eyes from 21 patients with BCR and equal number of eyes from control subjects. Diagnosis of BCR was confirmed on fundus fluorescein and indocyanine green angiography. Vascular calibres were measured using validated semiautomated software.

RESULTS

Patients with BCR had smaller retinal venular calibres central retinal venular equivalent (CRVE) than controls (211.3 versus 227.9 μm, p = 0.008). After adjusting for variables, the difference between the two groups for CRVE at baseline was statistically significant based on two different analysis methods. Central retinal venular equivalent (CRVE) was lower at the 6-month follow-up visit (206.2 versus 213.8 μm, p-value = 0.03), and arteriole-to-venule ratio was larger (0.74 versus 0.71, p = 0.04) in subjects with BCR. Arteriolar calibre (CRAE) remained the same.

CONCLUSION

This study provides novel insight into the pattern of vascular involvement in BCR. There was significant difference in the CRVE in patients with BCR. More studies are needed to correlate this data with visual function and treatment outcome and to validate the findings.

Multimodal imaging of the disease progression of birdshot chorioretinopathy

PURPOSE

To study outer retinal deterioration in relation to clinical disease activity in patients with birdshot chorioretinopathy using fundus autofluorescence and spectral-domain optical coherence tomography (OCT).

METHODS

A single-centre retrospective cohort study was carried out on 42 eyes of 21 patients with birdshot disease, using a multimodal imaging approach including fundus autofluorescence, OCT, fluorescein angiography and indocyanine green angiography in combination with a patient chart review. The patients' overall clinical activity of retinal vasculitis during the follow-up period was determined by periods of clinical activity as indicated by fluorescein angiography and associated treatment decisions. Image analysis was performed to examine the spatial correspondence between autofluorescence changes and disruption of the photoreceptor inner segment ellipsoid zone on OCT.

RESULTS

Three common types of outer retinal lesions were observed in fovea-centred images of 43% of patients: circular patches of chorioretinal atrophy, ellipsoid zone disruption on OCT, and outer retinal atrophy on autofluorescence and OCT. There was good spatial correspondence between ellipsoid zone disruption and areas of diffuse hyper-autofluorescence outside the fovea. Interestingly, the ellipsoid zone disruption recovered in four out of seven patients upon intensified therapeutic immunosuppression.

CONCLUSION

Most patients only developed peripapillary atrophy and occasional perivascular hypo-autofluorescence. A multimodal imaging approach with autofluorescence imaging and OCT may help to detect ellipsoid zone disruption in the central retina of patients with birdshot disease. Our results suggest that ellipsoid zone disruption may be related to both the activity and duration of retinal vasculitis, and could help to determine therapeutic success in birdshot disease.

ULTRA-WIDEFIELD FUNDUS IMAGING: A Review of Clinical Applications and Future Trends

PURPOSE

To review the basic principles of ultra-widefield fundus imaging and discuss its clinical utility for a variety of retinal and choroidal disorders.

METHODS

A systematic review of the PubMed database was performed using the search terms Optos, optomap, panoramic, ultra-widefield, wide-angle, and ellipsoid mirror. This yielded 158 publications of which 128 were selected based on content and relevance.

RESULTS

A total of 128 articles pertaining to ultra-widefield imaging were cited in this review.

CONCLUSION

Optos ultra-widefield imaging has become an essential tool for the identification of peripheral retinal and vascular pathology. The high resolution and multimodal capabilities of this device are also providing new insights into a variety of disorders, even those that primarily involve the posterior pole. Although the presence of artifact and the need for clinical validation are significant hurdles to more widespread use, ultra-widefield is evolving to become the standard-of-care imaging modality for many diseases and is finding new clinical and research applications such as for screening and telemedicine.

Spatial agreement between Goldmann visual field defects and fundus autofluorescence in patients with birdshot chorioretinopathy

BACKGROUND

The purpose of this paper is to study the spatial agreement between visual field defects and ultra-wide field (UWF) fundus autofluorescence (FAF) in patients with birdshot chorioretinopathy (BSCR). The study is a retrospective, cross-sectional analysis of a university uveitis practice. Eight (8) eyes of five (5) patients with BSCR were included. Inclusion criteria were ability to fixate reliably. Goldmann visual fields (GVF) and UWF FAF were obtained, digitalized, and standardized. Analysis was performed by measuring areas of overlap of hypo-autofluorescent FAF lesions and GVF scotomas within the central 60°. Overlap was calculated as a percentage of the total area of FAF and GVF, respectively. Average areas were also calculated.

RESULTS

The mean age of the subjects was 51 ± 12.28 years (range 38-69 years). 14 ± 23 % of the total lesion area identified as hypo-autofluorescent on FAF overlapped with scotoma. 28 ± 41 % of the GVF scotomas overlapped with hypo-autofluorescent FAF lesions. Average area of FAF hypo-autofluorescence was much larger (15.19 disc areas) than GVF (3.45 disc areas).

CONCLUSIONS

There appear to be larger total areas of hypo-autofluorescence on FAF than scotoma evidenced by GVF and only a small amount of overlap. The finding suggests that GVF is relatively insensitive to anatomic loss, which can be detected using FAF. Further studies are required to assess whether this finding holds true for automated white-on-white perimetry. In addition, more selective psychophysical stimuli may have higher sensitivity in detecting early functional loss that accompanies anatomic damage.