Imaging geographic atrophy: integrating structure and function to better understand the effects of new treatments.

Geographic atrophy (GA) is an advanced and irreversible form of age-related macular degeneration (AMD). Chronic low grade inflammation is thought to act as an initiator of this degenerative process, resulting in loss of photoreceptors (PRs), retinal pigment epithelium (RPE) and the underlying choriocapillaris. This review examined the challenges of clinical trials to date which have sought to treat GA, with particular reference to the successful outcome of C3 complement inhibition. Currently, optical coherence tomography (OCT) seems to be the most suitable method to detect GA and monitor the effect of treatment. In addition, the merits of using novel anatomical endpoints in detecting GA expansion are discussed. Although best-corrected visual acuity is commonly used to monitor disease in GA, other tests to determine visual function are explored. Although not widely available, microperimetry enables quantification of retinal sensitivity (RS) and macular fixation behaviour related to fundus characteristics. There is a spatial correlation between OCT/fundus autofluorescence evaluation of PR damage outside the area of RPE loss and RS on microperimetry, showing important associations with visual function. Standardisation of testing by microperimetry is necessary to enable this modality to detect AMD progression. Artificial intelligence (AI) analysis has shown PR layers integrity precedes and exceeds GA loss. Loss of the ellipsoid zone has been recognised as a primary outcome parameter in therapeutic trials for GA. The integrity of the PR layers imaged by OCT at baseline has been shown to be an important prognostic indicator. AI has the potential to be invaluable in personalising care and justifying treatment intervention.

Retinotopic cortical mapping in objective functional monitoring of macular therapy.

BACKGROUND/AIMS: To determine the suitability of functional MRI (fMRI) as an objective measure of macular function following therapeutic intervention; conventional psychophysical measures rely heavily on patient compliance. METHODS: Twenty patients with neovascular age-related macular degeneration (nAMD) were studied with high-resolution fMRI, visual acuity, reading accuracy and speed, contrast sensitivity (CS) and microperimetry (MP) before and after 3 monthly intravitreal injections of ranibizumab. Population-receptive field retinotopic maps calculated from fMRI data were compared with psychophysical measures and optical coherence tomography. RESULTS: Best-corrected visual acuity (BCVA) responders (≥5 letters) showed an increase of 29.5% in activated brain area, while non-responders showed a decrease of 0.8%. Radial histograms over eccentricity allowed quantification of the absolute number of significant voxels and thus differences before and after treatment. Responders showed increases in foveal (α<0.5°) activation, while non-responders did not. Absence of intraretinal fluid and preservation of outer retinal layers was associated with higher numbers of active V1 voxels and better BCVA. Higher voxel numbers were associated with improved reading performance and, less marked, with BCVA, CS and MP. CONCLUSION: The data show that retinotopic mapping using fMRI can successfully be applied objectively to evaluate the therapeutic response in nAMD patients treated with anti-vascular endothelial growth factor therapy. This demonstrates the ability of retinotopic mapping to provide an objective assessment of functional recovery at a cortical level; the technique can therefore be applied, in other degenerative macular diseases, to the assessment of potential therapeutic interventions such as gene therapy or cell replacement therapy.

Approved AI-based fluid monitoring to identify morphological and functional treatment outcomes in neovascular age-related macular degeneration in real-world routine (FRB!).

AIM: To predict antivascular endothelial growth factor (VEGF) treatment requirements, visual acuity and morphological outcomes in neovascular age-related macular degeneration (nAMD) using fluid quantification by artificial intelligence (AI) in a real-world cohort. METHODS: Spectral-domain optical coherence tomography data of 158 treatment-naïve patients with nAMD from the Fight Retinal Blindness! registry in Zurich were processed at baseline, and after initial treatment using intravitreal anti-VEGF to predict subsequent 1-year and 4-year outcomes. Intraretinal and subretinal fluid and pigment epithelial detachment volumes were segmented using a deep learning algorithm (Vienna Fluid Monitor, RetInSight, Vienna, Austria). A predictive machine learning model for future treatment requirements and morphological outcomes was built using the computed set of quantitative features. RESULTS: Two hundred and two eyes from 158 patients were evaluated. 107 eyes had a lower median (≤7) and 95 eyes had an upper median (≥8) number of injections in the first year, with a mean accuracy of prediction of 0.77 (95% CI 0.71 to 0.83) area under the curve (AUC). Best-corrected visual acuity at baseline was the most relevant predictive factor determining final visual outcomes after 1 year. Over 4 years, half of the eyes had progressed to macular atrophy (MA) with the model being able to distinguish MA from non-MA eyes with a mean AUC of 0.70 (95% CI 0.61 to 0.79). Prediction for subretinal fibrosis reached an AUC of 0.74 (95% CI 0.63 to 0.81). CONCLUSIONS: The regulatory approved AI-based fluid monitoring allows clinicians to use automated algorithms in prospectively guided patient treatment in AMD. Furthermore, retinal fluid localisation and quantification can predict long-term morphological outcomes.

Automated quantification of macular fluid in retinal diseases and their response to anti-VEGF therapy.

AIM: To objectively assess disease activity and treatment response in patients with retinal vein occlusion (RVO), neovascular age-related macular degeneration (nAMD) and centre-involved diabetic macular oedema (DME), using artificial intelligence-based fluid quantification. METHODS: Posthoc analysis of 2311 patients (11 151 spectral-domain optical coherence tomography volumes) from five clinical, multicentre trials, who received a flexible antivascular endothelial growth factor (anti-VEGF) therapy over a 12-month period. Fluid volumes were measured with a deep learning algorithm at baseline/months 1, 2, 3 and 12, for three concentric circles with diameters of 1, 3 and 6 mm (fovea, paracentral ring and pericentral ring), as well as four sectors surrounding the fovea (superior, nasal, inferior and temporal). RESULTS: In each disease, at every timepoint, most intraretinal fluid (IRF) per square millimetre was present at the fovea, followed by the paracentral ring and pericentral ring (p<0.0001). While this was also the case for subretinal fluid (SRF) in RVO/DME (p<0.0001), patients with nAMD showed more SRF in the paracentral ring than at the fovea up to month 3 (p<0.0001). Between sectors, patients with RVO/DME showed the highest IRF volumes temporally (p<0.001/p<0.0001). In each disease, more SRF was consistently found inferiorly than superiorly (p<0.02). At month 1/12, we measured the following median reductions of initial fluid volumes. For IRF: RVO, 95.9%/97.7%; nAMD, 91.3%/92.8%; DME, 37.3%/69.9%. For SRF: RVO, 94.7%/97.5%; nAMD, 98.4%/99.8%; DME, 86.3%/97.5%. CONCLUSION: Fully automated localisation and quantification of IRF/SRF over time shed light on the fluid dynamics in each disease. There is a specific anatomical response of IRF/SRF to anti-VEGF therapy in all diseases studied.

Microvascular abnormalities and long-term efficacy after stereotactic radiotherapy under continued intravitreal anti-VEGF treatment for neovascular AMD.

BACKGROUND: For treatment of neovascular age-related macular degeneration (nAMD), multiple intravitreal injections of drugs targeting vascular endothelial growth factors (VEGF) result in a high burden for patients and healthcare systems. Low-energy stereotactic radiotherapy (SRT) might reduce the anti-VEGF need. This study evaluated the long-term efficacy and safety of adjunct SRT to anti-VEGF injections in a treat-and-extend regimen in nAMD. METHODS: 50 consecutive patients were followed 3 years after single-session SRT, a safety analysis including standardised study imaging, and a reading centre based image analysis was performed after 2 years. RESULTS: After increase from baseline (4.24±0.66 weeks) to 12 months (7.52±3.05 weeks, p<0.001), mean recurrence-free anti-VEGF treatment interval remained stable at 24 (7.40±3.17, p=0.746) and 36 months (6.89±3.00, p=0.175). Mean visual acuity change was -5.8±15.9 and -11.0±20.1 letters at 24 and 36 months, respectively. 36% of eyes showed microvascular abnormalities (MVAs) on colour fundus photography and/or fluoresceine angiography most frequently located in parafoveal inferior and nasal regions. CONCLUSION: In real life, low-energy SRT was associated with a reduced anti-VEGF injection frequency through year 3. However, due to an observed visual acuity reduction and remarkable number of MVAs, a close follow-up of these patients is recommended. The real-life use, optimal treatment schedule and dose should be rediscussed critically.

Quality assessment of colour fundus and fluorescein angiography images using deep learning.

BACKGROUND/AIMS: Image quality assessment (IQA) is crucial for both reading centres in clinical studies and routine practice, as only adequate quality allows clinicians to correctly identify diseases and treat patients accordingly. Here we aim to develop a neural network for automated real-time IQA in colour fundus (CF) and fluorescein angiography (FA) images. METHODS: Training and evaluation of two neural networks were conducted using 2272 CF and 2492 FA images, with binary labels in four (contrast, focus, illumination, shadow and reflection) and three (contrast, focus, noise) modality specific categories plus an overall quality ranking. Performance was compared with a second human grader, evaluated on an external public dataset and in a clinical trial use-case. RESULTS: The networks achieved a F1-score/area under the receiving operator characteristic/precision recall curve of 0.907/0.963/0.966 for CF and 0.822/0.918/0.889 for FA in overall quality prediction with similar results in most categories. A clear relation between model uncertainty and prediction error was observed. In the clinical trial use-case evaluation, the networks achieved an accuracy of 0.930 for CF and 0.895 for FA. CONCLUSION: The presented method allows automated IQA in real time, demonstrating human-level performance for CF as well as FA. Such models can help to overcome the problem of human intergrader and intragrader variability by providing objective and reproducible IQA results. It has particular relevance for real-time feedback in multicentre clinical studies, when images are uploaded to central reading centre portals. Moreover, automated IQA as preprocessing step can support integrating automated approaches into clinical practice.

Longitudinal analysis of microvascular perfusion and neurodegenerative changes in early type 2 diabetic retinal disease.

AIM: To prospectively monitor subclinical changes in capillary perfusion and retinal layer thickness in patients with type 2 diabetes and early diabetic retinal disease over 2 years. METHODS: In this longitudinal study we performed biannual retinal vascular imaging using optical coherence tomography angiography (RTVue) to analyse the foveal avascular zone (FAZ) area, perimeter, acircularity index (AI) and parafoveal superficial/deep vessel density (VD). Spectral-domain optical coherence tomography (Spectralis) was used to measure the thickness of nine macular layers and the peripapillary nerve fibre layer. RESULTS: Among 117 eyes (58 left) of 59 patients (21 female), 105 had no diabetic retinopathy (DR), 6 mild and 6 moderate non-proliferative DR at baseline. We found DR progression in 13 eyes at year 2. The FAZ area (+0.008±0.002 mm2/year, p<0.0001), perimeter (+0.036±0.010 mm/year, p=0.006) and AI (+0.005±0.002/year, p=0.0280) increased significantly. A pronounced decrease was found in the superficial (-1.425±0.290%/year, p<0.0001) but not the deep VD. Inner neuroretinal loss was confined to the ganglion cell (-0.539±0.150 µm/year, p=0.0004) and the inner plexiform layer (-0.361±0.127 µm/year, p=0.0045). In the outer retina, we observed a statistically significant decrease in thickness in the outer plexiform, photoreceptor layer and pigment epithelium of -0.921±0.161 µm/year, -0.325±0.139 µm/year and -0.385±0.084 µm/year, respectively. CONCLUSION: Subclinical signs of microangiopathy and neurodegeneration appear in parallel and are highly progressive even in the earliest stages of diabetic retinal disease. Trial registration number EudraCT20156000239634.

Detection of diabetic neovascularisation using single-capture 65°-widefield optical coherence tomography angiography.

AIM: To assess the detection rate of retinal neovascularisation (NV) in eyes with proliferative diabetic retinopathy (PDR) using widefield optical coherence tomography angiography (WF-OCTA) in comparison to ultrawidefield fluorescein angiography (UWF-FA). METHODS: Single-capture 65°-WF-OCTA-imaging was performed in patients with NV at the disc or elsewhere (NVE) detected on UWF-FA using a modified PlexElite system and B-scans were examined for blood flow signals breaching the internal limiting membrane. Sensitivity of WF-OCTA and UWF colour fundus (UWF-CF) photography for correct diagnosis of PDR was determined and interdevice agreement (Fleiss' κ) between WF-OCTA and UWF-FA for detection of NV in the total gradable area and each retinal quadrant was evaluated. RESULTS: Fifty-nine eyes of 41 patients with PDR detected on UWF-FA were included. Sensitivity of detecting PDR on WF-OCTA scans was 0.95 in contrast to 0.78 on UWF-CF images. Agreement in detecting NVE between WF-OCTA and UWF-FA was high in the superotemporal (κ=0.98) and inferotemporal (κ=0.94) and weak in the superonasal (κ=0.24) and inferonasal quadrants (κ=0.42). On UWF-FA, 63% of NVEs (n=153) were located in the temporal quadrants with 93% (n=142) of them being detected on WF-OCTA scans. CONCLUSION: The high reliability of non-invasive WF-OCTA imaging in detecting PDR can improve clinical examination with the potential to replace FA as a single diagnostic tool.

RAP study, report 1: novel subtype of macular neovascularisation type III, cilioretinal MNV3.

PURPOSE: To report on patients with macular neovascularisation type III (MNV3) arising from cilioretinal arteries (CRAs) (cilioretinal macular neovascularisation type III (cMNV3)). METHODS: We reviewed baseline examinations of patients with neovascular age-related macular degeneration using multimodal imaging. We determined the type and distribution of MNV lesions in each cMNV3 case, the range of distances from the fovea, existence of exudative maculopathy, intraretinal haemorrhage and other morphological characteristics. 50 consecutive eyes with usual MNV3 without CRA were included as a control group. RESULTS: 102 eyes of 102 patients were identified with MNV3 lesions. Among these, we found 12 eyes (12%) with cMNV3, 84 eyes (82%) with usual MNV3 without CRA and 6 eyes (6%) with usual MNV3 with CRA. Ten cases of cMNV3 had one lesion, and two cases had two lesions. The lesions were distributed equally between the superior and inferior halves of the macula, whereas in the nasal and temporal halves, there were 8 (57%) and 6 (43%) lesions, respectively. All cMNV3 lesions were located between 500 and 1500 µm from the central fovea except one, which was located between 1500 and 3000 µm. None of the lesions had macular neovascularisation type I (MNV1) or macular neovascularisation type II (MNV2) elsewhere in both groups. Exudative maculopathy and intraretinal haemorrhage were found in seven (88%) and five (63%) of the eight pure cMNV3 cases, respectively. CONCLUSION: cMNV3 can be solitary or multiple, isolated or accompanied with usual MNV3 lesions, but not with concurrent MNV1 or MNV2. It is frequently associated with extensive exudative maculopathy, intraretinal haemorrhage and subretinal fluid.

Systematic ultrastructural comparison of swept-source and full-depth spectral domain optical coherence tomography imaging of diabetic macular oedema.

BACKGROUND/AIMS: Optical coherence tomography (OCT) is commonly used to diagnose and assess diabetic macular oedema (DME). Swept-source OCT (SS-OCT) promises improved imaging depth and more independence from media opacities. Heidelberg Spectralis full-depth imaging (FDI) combines details at different depths to one representation. The aim of this study was to determine the comparability of the imaging methods concerning DME ultrastructure. METHODS: Two graders assessed the presence of typical DME phenomena in eyes with centre-involving DME on Topcon Atlantis SS-OCT and Heidelberg Spectralis FDI spectral-domain OCT (SD-OCT) B-scans. Retinal layer segmentation was corrected and choroidal layers were manually segmented. Graders measured cyst and subretinal fluid (SRF) diameters and counted hyper-reflective foci (HRF). Findings were recorded and statistically analysed. RESULTS: Statistically significant systematic biases (Spectralis-Atlantis) were found for the HRF count (outside the central mm, -6.39, p=0.0338), chorioretinal thickness (central mm: -35.45 µm, p=0.00034), choroidal thickness (central mm: -60.97 µm, p=0.00004) and Sattler's layer thickness (-42.69 µm, p=0.0001). Intergrader agreement was excellent or very good for posterior vitreous detachment, vitreomacular attachment (central mm) and SRF presence in both devices. Manually delineated Sattler's layer thickness showed an intraclass correlation of 0.85 with FDI SD-OCT but 0.26 with SS-OCT (p=0.003). CONCLUSION: Prominent aspects such as cysts in the outer nuclear layer and SRF can be identified with comparable confidence, while a significant systematic bias underlies chorioretinal, choroidal and Sattler's layer thickness and HRF count. Specialists should use the same device at every examination during longitudinal clinical consideration or cross-sectional evaluation of these ultrastructural biomarkers.

Effect of posterior vitreous detachment on treat-and-extend versus monthly ranibizumab for neovascular age-related macular degeneration.

AIMS: To investigate the impact of posterior vitreous detachment (PVD) on the efficacy of treat-and-extend (T&E) ranibizumab in neovascular age-related macular degeneration. METHODS: In a post hoc analysis of a randomised controlled clinical trial, spectral-domain optical coherence tomography images of treatment-naïve patients randomised to receive T&E (n=265) or monthly (n=264) ranibizumab for 12 months were included. Certified, masked graders diagnosed the presence or the absence of complete PVD. The main outcome measures were the mean change in best-corrected visual acuity (BCVA) and central retinal thickness (CRT) at month 12, the number of administered ranibizumab injections and the proportion of patients extended to more than 8 weeks. RESULTS: At baseline, complete PVD was present in 51% and 56% of patients in the monthly and T&E arms, respectively. Mean change in BCVA at month 12 was +9.0 (PVD) vs +9.5 letters (no PVD, p=0.78) in monthly treated eyes, and +6.0 (PVD) vs +7.5 letters (no PVD, p=0.42) in T&E treated eyes. Conversely, mean change in CRT at month 12 was -174 (PVD) vs -173 µm (no PVD, p=0.98) in the monthly arm, and -175 (PVD) vs -164 µm (no PVD, p=0.58) in the T&E arm. In T&E treated patients, the median number of injections was eight vs nine (p=0.035). 71% of PVD eyes were extended successfully, compared with 55% of eyes without PVD (p=0.005). CONCLUSION: PVD was not found to impact functional and anatomical outcomes of T&E ranibizumab therapy. However, patients without a complete PVD required more retreatments and were significantly less likely to be successfully extended. TRIAL REGISTRATION NUMBER: NCT01948830.

Impact of drusen and drusenoid retinal pigment epithelium elevation size and structure on the integrity of the retinal pigment epithelium layer.

PURPOSE: To evaluate the impact of drusen size and structure on retinal pigment epithelium (RPE) and photoreceptor layers in eyes with early to intermediate age-related macular degeneration (AMD) using polarisation-sensitive optical coherence tomography (OCT). DESIGN: Retrospective investigation of an observational cross-sectional study. PARTICIPANTS: Patients with early to intermediate AMD. METHODS: Twenty-five eyes of 25 patients with drusen were imaged with polarisation-sensitive OCT using macular volume scans. Each scan was manually graded for six distinct drusen characteristics and the integrity of both the overlying RPE and photoreceptor layer. The central scan of each single druse, as well as its diameter and location, were selected for statistical calculations. RESULTS: A total number of 5933 individual drusen including their adjacent RPE and photoreceptor layer were evaluated. 41.3% of all drusen demonstrated an intact overlying RPE; in 28.1% the RPE layer was irregular, but continuous. In 30.6%, the RPE layer signal was discontinuous above the area of drusen. The level of RPE alteration was significantly related to shape (p<0.001), internal reflectivity (p<0.001) and homogeneity (p<0.001) of the drusen and their diameter, with a higher probability for larger drusen to have a discontinuous RPE (OR 3.2, p<0.001). The number of drusen showing overlying foci or an altered photoreceptor layer was too small to be conclusive, but showed a trend towards an altered RPE if present. CONCLUSIONS: Polarisation-sensitive OCT reveals a correlation between specific drusen characteristics and the integrity of the overlying RPE layer. Drusen diameter and configuration were significantly associated with RPE loss.

Predictive imaging biomarkers relevant for functional and anatomical outcomes during ranibizumab therapy of diabetic macular oedema.

BACKGROUND/AIMS: The objective is to identify imaging biomarkers in optical coherence tomography predicting functional/anatomical outcomes in diabetic macular oedema (DMO). METHODS: The presented study is a post hoc analysis of the RESTORE/RESTORE-extension studies. Best-corrected visual acuity (BCVA) was analysed using general estimating equation models using treatment group/morphological features as predictor variables. In addition, linear multiple regression models analysed BCVA gain up to 12 and 36 months with BCVA/morphological baseline characteristics as independent predictor variables. The correlations between central retinal thickness (CRT)/BCVA were calculated as Spearman's/Pearson's correlation coefficients. RESULTS: A weak negative linear correlation between CRT/BCVA was observed in all study arms at baseline (r=-0.34, p<0.001) and at month 36 (r=-0.26, p<0.001). Patients with baseline height of intraretinal cystoid fluid (IRC) ≤380 µm had better baseline BCVA compared with patients with IRC height >380 µm (64.84±10.63 vs 61.66±9.92 letters; p=0.0071, respectively), which was maintained until the end of month 12 (70.5±12.33 vs 67.0±14.09 letters; p=0.0252, respectively). With laser, there was a trend for patients with subretinal fluid (SRF) at baseline to lose BCVA letters at month 12 (-5.38±16.54 vs 2.49±9.72 letters; p=0.1038), whereas ranibizumab patients trended towards higher BCVA gains (10.28±7.14 vs 6.76±7.67; p=0.0563), compared with those without SRF. With combined therapy, all patients had similar BCVA gains regardless of SRF (p=0.3768). CONCLUSION: With ranibizumab treatment, the height of IRC spaces at baseline was a better predictor of functional/anatomical improvement than CRT alone. There was also a trend for SRF to show a positive impact on ranibizumab therapy response and a negative impact on laser therapy response.

Automatic and manual segmentation of healthy retinas using high-definition optical coherence tomography.

PURPOSE: This study compared automatic- and manual segmentation modalities in the retina of healthy eyes using high-definition optical coherence tomography (HD-OCT). METHODS: Twenty retinas in 20 healthy individuals were examined using an HD-OCT system (Carl Zeiss Meditec, Inc.). Three-dimensional imaging was performed with an axial resolution of 6 µm at a maximum scanning speed of 25,000 A-scans/second. Volumes of 6 × 6 × 2 mm were scanned. Scans were analysed using a matlab-based algorithm and a manual segmentation software system (3D-Doctor). The volume values calculated by the two methods were compared. RESULTS: Statistical analysis revealed a high correlation between automatic and manual modes of segmentation. The automatic mode of measuring retinal volume and the corresponding three-dimensional images provided similar results to the manual segmentation procedure. Both methods were able to visualize retinal and subretinal features accurately. CONCLUSIONS: This study compared two methods of assessing retinal volume using HD-OCT scans in healthy retinas. Both methods were able to provide realistic volumetric data when applied to raster scan sets. Manual segmentation methods represent an adequate tool with which to control automated processes and to identify clinically relevant structures, whereas automatic procedures will be needed to obtain data in larger patient populations.

Quantification of the therapeutic response of intraretinal, subretinal, and subpigment epithelial compartments in exudative AMD during anti-VEGF therapy.

PURPOSE: To analyze the functional and morphologic effects of different ranibizumab treatment regimens on retinal and subretinal as well as sub-RPE compartments in neovascular age-related macular degeneration (nAMD) using spectral-domain optical coherence tomography (SD-OCT) and manual segmentation software. METHODS: Twenty-seven eyes of 27 patients with nAMD were examined over a 12-month period. Two treatment arms received either monthly or quarterly administered intravitreal ranibizumab. Intraretinal, subretinal, and sub-RPE volume equivalents were delineated using manual segmentation software over a defined series of B-scans obtained by SD-OCT. The mean area in pixels was calculated for each compartment at each time interval. RESULTS: SD-OCT and manual segmentation allowed for exact identification of intraretinal, subretinal and sub-RPE compartments and their responses to different treatment regimens. The loading dose demonstrated a corresponding treatment effect on all anatomic parameters. In contrast to the sub-RPE compartment, intraretinal fluid accumulation and subretinal fluid accumulation (SRFA) demonstrated an immediate response to ranibizumab therapy. The overall plasticity of the morphologic response declined over time. In general, SRFA demonstrated greater sensitivity for therapeutic effects and was more frequently associated with recurrent disease. CONCLUSIONS: An exact quantification of fluid in different anatomic compartments based on SD-OCT imaging, using appropriate segmentation software systems, may be useful to determine optimal treatment and retreatment parameters and explains the lack of correlation of best-corrected visual acuity and conventional OCT values.

Three-dimensional angiographic imaging of leakage in branch retinal vein occlusion.

PURPOSE: Optical coherence tomography (OCT) is used to image branch retinal vein occlusion (BRVO) but lacks information about leakage dynamics and perfusion status. Topographical angiography (TAG) is capable of providing this information and has been described previously in age-related macular degeneration. This study evaluates TAG in BRVO. METHODS: We included 56 eyes of 40 consecutive patients with BRVO and a reduction in central vision. Two groups were established based on whether argon laser coagulation was performed or not. A standardized follow-up was performed. The chorioretinal fluorescence pattern was reconstructed following TAG. Quantitative measurements were also performed. RESULTS: TAG performed from indocyanine green angiography (ICGA) showed smaller lesion size (LS) compared to fluorescein angiography (FA) (mean difference: early phase = -1.6 mm(2), late phase = -1.8 mm(2)). The extent of mean LS from early to late phase increased by 0.8 mm(2) in FA and by 0.6 mm(2) in ICGA. TAG could visualize different degrees of leakage topographically. CONCLUSION: TAG gives new insights into the pathophysiology of BRVO: it enables the visualization of dynamics of leakage and the demonstration of the effects of intravasal stasis. Furthermore, TAG is less impaired by masking phenomena than FA. Functional retinal imaging shows distinct advantages over OCT: quantification of leakage activity is possible using TAG.