Macrophages coordinate immune response to laser-induced injury via extracellular traps.

BACKGROUND: Retinal degeneration results from disruptions in retinal homeostasis due to injury, disease, or aging and triggers peripheral leukocyte infiltration. Effective immune responses rely on coordinated actions of resident microglia and recruited macrophages, critical for tissue remodeling and repair. However, these phagocytes also contribute to chronic inflammation in degenerated retinas, yet the precise coordination of immune response to retinal damage remains elusive. Recent investigations have demonstrated that phagocytic cells can produce extracellular traps (ETs), which are a source of self-antigens that alter the immune response, which can potentially lead to tissue injury. METHODS: Innovations in experimental systems facilitate real-time exploration of immune cell interactions and dynamic responses. We integrated in vivo imaging with ultrastructural analysis, transcriptomics, pharmacological treatments, and knockout mice to elucidate the role of phagocytes and their modulation of the local inflammatory response through extracellular traps (ETs). Deciphering these mechanisms is essential for developing novel and enhanced immunotherapeutic approaches that can redirect a specific maladaptive immune response towards favorable wound healing in the retina. RESULTS: Our findings underscore the pivotal role of innate immune cells, especially macrophages/monocytes, in regulating retinal repair and inflammation. The absence of neutrophil and macrophage infiltration aids parenchymal integrity restoration, while their depletion, particularly macrophages/monocytes, impedes vascular recovery. We demonstrate that macrophages/monocytes, when recruited in the retina, release chromatin and granular proteins, forming ETs. Furthermore, the pharmacological inhibition of ETosis support retinal and vascular repair, surpassing the effects of blocking innate immune cell recruitment. Simultaneously, the absence of ETosis reshapes the inflammatory response, causing neutrophils, helper, and cytotoxic T-cells to be restricted primarily in the superficial capillary plexus instead of reaching the damaged photoreceptor layer. CONCLUSIONS: Our data offer novel insights into innate immunity's role in responding to retinal damage and potentially help developing innovative immunotherapeutic approaches that can shift the immune response from maladaptive to beneficial for retinal regeneration.

Microbiome and Retinal Vascular Diseases.

The gut microbiome consists of more than a thousand different microbes and their associated genes and microbial metabolites. It influences various host metabolic pathways and is therefore important for homeostasis. In recent years, its influence on health and disease has been extensively researched. Dysbiosis, or imbalance in the gut microbiome, is associated with several diseases. Consequent chronic inflammation may lead to or promote inflammatory bowel disease, obesity, diabetes mellitus, atherosclerosis, alcoholic and non-alcoholic liver disease, cirrhosis, hepatocellular carcinoma, and other diseases. The pathogenesis of the three most common retinal vascular diseases, diabetic retinopathy, retinal vein occlusion, and retinal artery occlusion, may also be influenced by an altered microbiome and associated risk factors such as diabetes mellitus, atherosclerosis, hypertension, and obesity. Direct cause-effect relationships remain less well understood. A potential prevention or treatment modality for these diseases could be targeting and modulating the individual's gut microbiome.

Dupilumab-associated ocular surface disease is characterized by a shift from Th2/Th17 toward Th1/Th17 inflammation.

BACKGROUND: Dupilumab is used for the treatment of atopic dermatitis (AD). Approximately one third of AD patients develop a dupilumab-associated ocular surface disease (DAOSD), of which the pathomechanism is poorly understood. This study aimed at investigating inflammatory markers in tear fluids of patients on dupilumab therapy. METHODS: Tear fluids were collected from AD patients with DAOSD (ADwDAOSD), AD patients without DAOSD (ADw/oDAOSD), and non-AD patients before and during dupilumab therapy, and analyzed using a specialized proteomic approach quantifying inflammatory markers. The ocular surface microbiome was determined by next generation sequencing technology. RESULTS: Upon dupilumab therapy, an upregulation of 31 inflammatory markers was observed in DAOSD tear fluids compared to baseline in AD patients. While IL-12B was upregulated in both ADwDAOSD and ADw/oDAOSD groups, the pattern of inflammatory markers significantly differed between groups and over time. In the ADwDAOSD group, a shift from a mixed Th2/Th17 pattern at baseline toward a Th1/Th17 profile under dupilumab was observed. Furthermore, an upregulation of remodeling and fibrosis markers was seen in DAOSD. Semantic map and hierarchical cluster analyses of baseline marker expression revealed four clusters distinguishing between AD and non-AD as well as ADwDAOSD and ADw/oDAOSD patient groups. In a pilot study, dupilumab therapy was associated with a decrease in richness of the ocular surface microbiome. CONCLUSIONS: DAOSD is characterized by a Th1/Th17 cytokine profile and an upregulation of markers known to promote remodeling and fibrosis. The expression pattern of inflammatory markers in tear fluids at baseline might serve as a prognostic factor for DAOSD.

Proliferative vitreoretinopathy: an update on the current and emerging treatment options.

Proliferative vitreoretinopathy (PVR) remains the main cause of failure in retinal detachment (RD) surgery and a demanding challenge for vitreoretinal surgeons. Despite the large improvements in surgical techniques and a better understanding of PVR pathogenesis in the last years, satisfactory anatomical and visual outcomes have not been provided yet. For this reason, several different adjunctive pharmacological agents have been investigated in combination with surgery. In this review, we analyze the current and emerging adjunctive treatment options for the management of PVR and we discuss their possible clinical application and beneficial role in this subgroup of patients.

BASELINE SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHIC RETINAL LAYER FEATURES IDENTIFIED BY ARTIFICIAL INTELLIGENCE PREDICT THE COURSE OF CENTRAL SEROUS CHORIORETINOPATHY.

PURPOSE: To identify optical coherence tomography (OCT) features to predict the course of central serous chorioretinopathy (CSC) with an artificial intelligence-based program. METHODS: Multicenter, observational study with a retrospective design. Treatment-naïve patients with acute CSC and chronic CSC were enrolled. Baseline OCTs were examined by an artificial intelligence-developed platform (Discovery OCT Fluid and Biomarker Detector, RetinAI AG, Switzerland). Through this platform, automated retinal layer thicknesses and volumes, including intaretinal and subretinal fluid, and pigment epithelium detachment were measured. Baseline OCT features were compared between acute CSC and chronic CSC patients. RESULTS: One hundred and sixty eyes of 144 patients with CSC were enrolled, of which 100 had chronic CSC and 60 acute CSC. Retinal layer analysis of baseline OCT scans showed that the inner nuclear layer, the outer nuclear layer, and the photoreceptor-retinal pigmented epithelium complex were significantly thicker at baseline in eyes with acute CSC in comparison with those with chronic CSC ( P < 0.001). Similarly, choriocapillaris and choroidal stroma and retinal thickness (RT) were thicker in acute CSC than chronic CSC eyes ( P = 0.001). Volume analysis revealed average greater subretinal fluid volumes in the acute CSC group in comparison with chronic CSC ( P = 0.041). CONCLUSION: Optical coherence tomography features may be helpful to predict the clinical course of CSC. The baseline presence of an increased thickness in the outer retinal layers, choriocapillaris and choroidal stroma, and subretinal fluid volume seems to be associated with acute course of the disease.

Exploring the Ocular Surface Microbiome and Tear Proteome in Glaucoma.

Although glaucoma is a leading cause of irreversible blindness worldwide, its pathogenesis is incompletely understood, and intraocular pressure (IOP) is the only modifiable risk factor to target the disease. Several associations between the gut microbiome and glaucoma, including the IOP, have been suggested. There is growing evidence that interactions between microbes on the ocular surface, termed the ocular surface microbiome (OSM), and tear proteins, collectively called the tear proteome, may also play a role in ocular diseases such as glaucoma. This study aimed to find characteristic features of the OSM and tear proteins in patients with glaucoma. The whole-metagenome shotgun sequencing of 32 conjunctival swabs identified Actinobacteria, Firmicutes, and Proteobacteria as the dominant phyla in the cohort. The species Corynebacterium mastitidis was only found in healthy controls, and their conjunctival microbiomes may be enriched in genes of the phospholipase pathway compared to glaucoma patients. Despite these minor differences in the OSM, patients showed an enrichment of many tear proteins associated with the immune system compared to controls. In contrast to the OSM, this emphasizes the role of the proteome, with a potential involvement of immunological processes in glaucoma. These findings may contribute to the design of new therapeutic approaches targeting glaucoma and other associated diseases.

Endothelial Toll-like receptor 4 is required for microglia activation in the murine retina after systemic lipopolysaccharide exposure.

BACKGROUND: Clustering of microglia around the vasculature has been reported in the retina and the brain after systemic administration of lipopolysaccharides (LPS) in mice. LPS acts via activation of Toll-like receptor 4 (TRL4), which is expressed in several cell types including microglia, monocytes and vascular endothelial cells. The purpose of this study was to investigate the effect of systemic LPS in the pigmented mouse retina and the involvement of endothelial TLR4 in LPS-induced retinal microglia activation. METHODS: C57BL/6J, conditional knockout mice that lack Tlr4 expression selectively on endothelial cells (TekCre-posTlr4loxP/loxP) and TekCre-negTlr4loxP/loxP mice were used. The mice were injected with 1 mg/kg LPS via the tail vein once per day for a total of 4 days. Prior to initiation of LPS injections and approximately 5 h after the last injection, in vivo imaging using fluorescein angiography and spectral-domain optical coherence tomography was performed. Immunohistochemistry, flow cytometry, electroretinography and transmission electron microscopy were utilized to investigate the role of endothelial TLR4 in LPS-induced microglia activation and retinal function. RESULTS: Activation of microglia, infiltration of monocyte-derived macrophages, impaired ribbon synapse organization and retinal dysfunction were observed after the LPS exposure in C57BL/6J and TekCre-negTlr4loxP/loxP mice. None of these effects were observed in the retinas of conditional Tlr4 knockout mice after the LPS challenge. CONCLUSIONS: The findings of the present study suggest that systemic LPS exposure can have detrimental effects in the healthy retina and that TLR4 expressed on endothelial cells is essential for retinal microglia activation and retinal dysfunction upon systemic LPS challenge. This important finding provides new insights into the role of microglia-endothelial cell interaction in inflammatory retinal disease.

Animal model of subretinal fibrosis without active choroidal neovascularization.

Subretinal fibrosis can occur during neovascular age-related macular degeneration (nAMD) and consequently provokes progressing deterioration of AMD patient's vision. Intravitreal anti-vascular endothelial growth factor (VEGF) injections decrease choroidal neovascularization (CNV), however, subretinal fibrosis remains principally unaffected. So far, no successful treatment nor established animal model for subretinal fibrosis exists. In order to investigate the impact of anti-fibrotic compounds on solely fibrosis, we refined a time-dependent animal model of subretinal fibrosis without active choroidal neovascularization (CNV). To induce CNV-related fibrosis, wild-type (WT) mice underwent laser photocoagulation of the retina with rupture of Bruch's membrane. The lesions volume was assessed with optical coherence tomography (OCT). CNV (Isolectin B4) and fibrosis (type 1 collagen) were separately quantified with confocal microscopy of choroidal whole-mounts at every time point post laser induction (day 7-49). In addition, OCT, autofluorescence and fluorescence angiography were carried out at designated timepoints (day 7, 14, 21, 28, 35, 42, 49) to monitor CNV and fibrosis transformation over time. From 21 to 49 days post laser lesion leakage in the fluorescence angiography decreased. Correspondingly, Isolectin B4 decreased in lesions of choroidal flat mounts and type 1 collagen increased. Fibrosis markers, namely vimentin, fibronectin, alpha-smooth muscle actin (α-SMA) and type 1 collagen were detected at different timepoints of tissue repair in choroids and retinas post laser. These results prove that the late phase of the CNV-related fibrosis model enables screening of anti-fibrotic compounds to accelerate the therapeutic advancement for the prevention, reduction, or inhibition of subretinal fibrosis.

The Human Ocular Surface Microbiome and Its Associations with the Tear Proteome in Dry Eye Disease.

Although dry eye disease (DED) is one of the most common ocular surface diseases worldwide, its pathogenesis is incompletely understood, and treatment options are limited. There is growing evidence that complex interactions between the ocular surface microbiome (OSM) and tear fluid constituents, potentially leading to inflammatory processes, are associated with ocular surface diseases such as DED. In this study, we aimed to find unique compositional and functional features of the OSM associated with human and microbial tear proteins in patients with DED. Applying whole-metagenome shotgun sequencing of forty lid and conjunctival swabs, we identified 229 taxa, with Actinobacteria and Proteobacteria being the most abundant phyla and Propionibacterium acnes the dominating species in the cohort. When DED patients were compared to controls, the species Corynebacterium tuberculostearicum was more abundant in conjunctival samples, whereas the family Propionibacteriaceae was more abundant in lid samples. Functional analysis showed that genes of L-lysine biosynthesis, tetrapyrrole biosynthesis, 5-aminoimidazole ribonucleotide biosynthesis, and the super pathway of L-threonine biosynthesis were enriched in conjunctival samples of controls. The relative abundances of Acinetobacter johnsonii correlated with seven human tear proteins, including mucin-16. The three most abundant microbial tear proteins were the chaperone protein DnaK, the arsenical resistance protein ArsH, and helicase. Compositional and functional features of the OSM and the tear proteome are altered in patients with DED. Ultimately, this may help to design novel interventional therapeutics to target DED.

Effect of Inhibition of Colony-Stimulating Factor 1 Receptor on Choroidal Neovascularization in Mice.

Neovascular age-related macular degeneration is one of the leading causes of blindness. Microglia and macrophages play a critical role in choroidal neovascularization (CNV) and may, therefore, be potential targets to modulate the disease course. This study evaluated the effect of the colony-stimulating factor-1 receptor inhibitor PLX5622 on experimental laser-induced CNV. A 98% reduction of retinal microglia cells was observed in the retina 1 week after initiation of PLX5622 treatment, preventing accumulation of macrophages within the laser site and leading to a reduction of leukocytes within the choroid after CNV induction. Mice treated with PLX5622 had a significantly faster decrease of the CNV lesion size, as revealed by in vivo imaging and immunohistochemistry from day 3 to day 14 compared with untreated mice. Several inflammatory modulators, such as chemokine (C-C motif) ligand 9, granulocyte-macrophage colony-stimulating factor, soluble tumor necrosis factor receptor-I, IL-1α, and matrix metallopeptidase-2, were elevated in the acute phase of the disease when microglia were ablated with PLX5622, whereas other cytokines (eg, interferon-γ, IL-4, and IL-10) were reduced. Our results suggest that colony-stimulating factor-1 receptor inhibition may be a novel therapeutic target in patients with neovascular age-related macular degeneration.

Ciliary body length revisited by anterior segment optical coherence tomography: implications for safe access to the pars plana for intravitreal injections.

PURPOSE: To investigate the dependence of the ciliary body length (CBL) on the axial length (AL) and to draw conclusions on implications regarding safe pars plana access for intravitreal injections and vitreoretinal surgery. METHODS: A total of 200 individuals (mean age 42 years, SD ± 15.4) were enrolled in the study. Objective refraction and AL were obtained. Spherical equivalent (SE) was calculated. Anterior segment optical coherence tomography (ASOCT) was used to image and measure the CBL. RESULTS: The mean SE was - 1.64 diopters (SD ± 3.15, range - 14.5 to + 9 diopters) and the mean AL was 24.19 mm (SD ± 1.65, range 19.8-32.2 mm). There was a significant correlation between SE and AL (r2 = 0.62, p < 0.0001). Mean CBL correlated significantly with age (r2 = 0.11, p < 0.0001), AL (r2 = 0.23, p < 0.0001) and SE (r2 = 0.25, p < 0.0001). The mean CBL was 3351 µm (SD ± 459, range 2184-4451 µm). Three separate groups were defined by their AL with a normal AL group (AL 22.5 to 25 mm), a short AL group (AL < 22.5 mm) and a long AL group (AL > 25 mm). The mean CBL in the normal AL group was 3311 µm (SD ± 427), in the short AL group 2936 µm (SD ± 335) and in the long AL group 3715 µm (SD ± 365), and differed significantly (p < 0.0001) when compared. CONCLUSION: For interventions requiring pars plana access (as an intravitreal injection or vitreoretinal surgery), an incision distance of 3.5-4.0 mm posterior to the limbus is recommended. In our research, however, a difference of 0.77 mm in mean CBL between the group with short AL and the group with long AL is demonstrated, implying that the mean CBL in very short and very long eyes differs significantly. These findings suggest that the AL should be taken into account for pars plana access and that it would be advisable to prefer the shorter or longer recommended distance (3.5 and 4.0 mm, respectively) from the limbus, which correlates with the AL. If AL is > 25 mm, a distance of 4.0 mm from the limbus should be chosen; and if AL is < 22.5 mm, a distance of 3.5 mm seems adequate. TRIAL REGISTRATION NUMBER AND DATE: NCT00564291, 27 Nov 2007.

IMAGING ARTIFACTS IN FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY.

PURPOSE: To investigate and quantify the influence of imaging artifacts on retinal fluorescence lifetime (FLIO) values and to provide helpful hints and tricks to avoid imaging artifacts and to improve FLIO image acquisition quality. METHODS: A systematic analysis of potential parameters influencing FLIO quality and/or fluorescence lifetime values was performed in a prospective systematic experimental imaging study in five eyes of five healthy subjects. For image acquisition, a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering) was used. Quantitative analysis of FLIO lifetime changes due to imaging artifacts was performed. RESULTS: Imaging artifacts with significant influence on fluorescence lifetimes included too short image acquisition time, insufficient illumination, ocular surface problems, and image defocus. Prior use of systemic or topical fluorescein makes analysis of retinal fluorescence lifetimes impossible. CONCLUSION: Awareness of possible sources of imaging artifacts is important for FLIO image acquisition and analysis. Therefore, standardized imaging and analysis procedure in FLIO is crucial for high-quality image acquisition and the possibility for systematic quantitative fluorescence lifetime analysis.

LONGITUDINAL FOVEAL FLUORESCENCE LIFETIME CHARACTERISTICS IN GEOGRAPHIC ATROPHY USING FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY.

PURPOSE: Short foveal fluorescence lifetimes (fFLT) in geographic atrophy are typically found in eyes with foveal sparing (FS) but may also occur in eyes without FS. We investigated whether short fFLT could serve as a functional biomarker for disease progression in geographic atrophy. METHODS: Thirty three eyes were followed over the course of 4 to 6 years. Foveal sparing was assessed using fluorescence lifetime imaging ophthalmoscopy, optical coherence tomography, fundus Autofluorescence, and macular pigment optical density. RESULTS: Eyes with FS exhibited shorter fFLT compared with eyes without FS. Short fFLT (<600 ps) were measured in all eyes with FS and half of the eyes without FS. Eyes with FS showed a bigger increase in fFLT per year (+39/+30 ps (short spectral channel/long spectral channel) in FS versus +29/+22 ps (short spectral channel/long spectral channel) in non FS). The best-corrected distance visual acuity correlated significantly with fFLT (P = 0.018 and P = 0.005 for short spectral channel/long spectral channel). Macular pigment optical density measurements correlated significantly with fFLT but not in all spectral channels (P ranging from 0.018 to 0.077). CONCLUSION: In geographic atrophy, shorter fFLT are associated with FS but they can also be observed in eyes without FS. Our longitudinal data suggest that shorter fFLT features in eyes with loss of FS represent an earlier stage of disease and may be more prone to loss of the visual acuity.

Inhibition of inflammatory cells delays retinal degeneration in experimental retinal vein occlusion in mice.

The role of microglia in retinal inflammation is still ambiguous. Branch retinal vein occlusion initiates an inflammatory response whereby resident microglia cells are activated. They trigger infiltration of neutrophils that exacerbate blood-retina barrier damage, regulate postischemic inflammation and irreversible loss of neuroretina. Suppression of microglia-mediated inflammation might bear potential for mitigating functional impairment after retinal vein occlusion (RVO). To test this hypothesis, we depleted microglia by PLX5622 (a selective tyrosine kinase inhibitor that targets the colony-stimulating factor-1 receptor) in fractalkine receptor reporter mice (Cx3cr1gfp/+ ) subjected to various regimens of PLX5622 treatment and experimental RVO. Effectiveness of microglia suppression and retinal outcomes including retinal thickness as well as ganglion cell survival were compared to a control group of mice with experimental vein occlusion only. PLX5622 caused dramatic suppression of microglia. Despite vein occlusion, reappearance of green fluorescent protein positive cells was strongly impeded with continuous PLX5622 treatment and significantly delayed after its cessation. In depleted mice, retinal proinflammatory cytokine signaling was diminished and retinal ganglion cell survival improved by almost 50% compared to nondepleted animals 3 weeks after vein occlusion. Optical coherence tomography suggested delayed retinal degeneration in depleted mice. In summary, findings indicate that suppression of cells bearing the colony-stimulating factor-1 receptor, mainly microglia and monocytes, mitigates ischemic damage and salvages retinal ganglion cells. Blood-retina barrier breakdown seems central in the disease mechanism, and complex interactions between different cell types composing the blood-retina barrier as well as sustained hypoxia might explain why the protective effect was only partial.

FLUORESCENCE LIFETIME PATTERNS IN MACULAR TELANGIECTASIA TYPE 2.

PURPOSE: Type 2 idiopathic macular telangiectasia (MacTel) is a rare bilateral neurodegenerative disease characterized by alterations in the macular capillary network leading to central vision loss. The purpose of this study was to quantify disease-specific retinal fluorescence lifetime patterns in patients with MacTel using fluorescence lifetime imaging ophthalmoscopy. PARTICIPANTS: Both eyes of 14 patients (mean age ± SEM, 67.8 ± 6.4 years) with a clinical diagnosis of MacTel Type 2 and 14 healthy age-matched controls (age 69.8 ± 6.4 years) were included in this study. METHODS: All participants were imaged with a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering, Germany). Mean retinal fluorescence lifetimes (Tm) were obtained in the short spectral channels (498-560 nm) and long spectral channels (560-720 nm). Clinical features, fundus images, fundus autofluorescence intensity images, spectral domain optical coherence tomography, and corresponding macular pigment optical density measurements using a modified confocal scanning laser ophthalmoscope (mpHRA) were further analyzed. Patients were classified into five phenotypic subgroups using the Gass and Blodi classification. RESULTS: Mean fluorescence lifetimes were significantly prolonged temporal to the fovea in patients with MacTel compared with healthy controls (mean ± SEM: short spectral channels 543 ± 61 ps vs. 304 ± 9 ps; P < 0.0001; long spectral channels: 447 ± 26 ps vs. 348 ± 11 ps; P < 0.0001), and appeared as a crescent or ring-shaped pattern. Prolonged lifetime patterns correlated with decreased macular pigment density on macular pigment optical density measurements. Follow-up examinations were performed in four MacTel patients, which revealed an increase of short spectral channel Tm of 22% over 2.1 years in the temporal fovea. CONCLUSION: This study confirms that fundus autofluorescence lifetimes display characteristic patterns in patients with MacTel Type 2 disease and provide information about macular pigment and possibly photoreceptor loss. Fluorescence lifetime prolongation correlates with disease severity and may therefore be a useful addition to other imaging modalities for assessing disease progression in MacTel Type 2.

FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY: Findings After Surgical Reattachment of Macula-Off Rhegmatogenous Retinal Detachment.

PURPOSE: The purpose of this study was to investigate fluorescence lifetime imaging ophthalmoscopy lifetimes after macula-off rhegmatogenous retinal detachment (RRD) repair. METHODS: Fifty-eight patients with successful macula-off RRD reattachment surgery were included. Retinal autofluorescence was excited with 470 nm, and amplitude-weighted mean fluorescence lifetimes (Tm) were measured in a short spectral channel (SSC, 498-560 nm) and a long spectral channel (LSC, 560-720 nm). Tm were obtained within a standardized Early Treatment Diabetic Retinopathy Study grid and correlated with Tm. The unaffected fellow eye served as control. RESULTS: Fifty-eight patients (age: 65 ± 1.6 years, 11 women) were imaged at median 1.5 months postoperatively. Tm were significantly prolongxxxed within areas of previously detached retina in the long spectral channel and particularly in the central subfield in the short spectral channel. Short lifetimes in the center of the Early Treatment Diabetic Retinopathy Study grid correlated with better visual acuity (short spectral channel; r = 0.18, P = 0.001, long spectral channel; r = 0.08, P = 0.03). Areas of residual subretinal fluid pockets in four RRD eyes displayed short fluorescence lifetimes. CONCLUSION: Areas of previously detached retina exhibit significant fluorescence lifetime changes. We found a significant correlation of fluorescence lifetimes within the fovea with visual acuity after successful RRD repair. Our data suggests that the prolongation of fluorescence lifetimes in the fovea is mainly driven by loss of macular pigment. Therefore, fluorescence lifetime imaging ophthalmoscopy may be useful in the prediction of long-term functional outcomes after macula-off RRD surgery.

Fluorescence Lifetime Patterns of Retinal Pigment Epithelium Atrophy in Patients with Stargardt Disease and Age-Related Macular Degeneration.

PURPOSE: To investigate whether autofluorescence lifetime patterns within retinal pigment epithelium (RPE) atrophy differ between age-related macular degeneration (AMD) and Stargardt disease (STGD). METHODS: Mean retinal autofluorescence lifetimes were measured in a short and a long spectral channel (SSC: 498-560 nm; LSC: 560-720 nm). Mean retinal fluorescence lifetimes were analyzed with corresponding clinical features, fundus images, fundus autofluorescence intensity images, and optical coherence tomography. Mean fluorescence lifetime values of atrophic areas were compared between the two cohorts and within the same patient to adjacent nonatrophic regions. RESULTS: Mean fluorescence lifetimes within areas with RPE atrophy of 13 patients with STGD (mean age ± SEM 43.7 ± 5 years) and 30 patients with geographic atrophy (mean age: 78 ± 2 years) were analyzed and compared to age-matched healthy participants. The mean area of RPE atrophy in STGD and AMD was 6.6 ± 2.3 mm2 (range: 0.66-33.17 mm2) and 17.5 ± 3.8 mm2 (range: 0.58-50.02 mm2), respectively. In patients with AMD, atrophic areas revealed significantly longer mean fluorescence lifetime values as compared with patients with STGD (SSC: 997 ± 60 vs. 363 ± 26 ps; LSC: 880 ± 46 vs. 393 ± 23 ps; p < 0.0001). CONCLUSIONS: This study established that RPE atrophy in patients secondary to STGD and AMD display distinctive mean fluorescence lifetime characteristics. As retinal fluorescence lifetimes within areas of RPE atrophy were significantly longer in AMD patients, the analysis of specific lifetime patterns may provide additional insight into the disease processes and the pathogenetic mechanisms in the development of atrophic patches in AMD and STGD.

EXIT STRATEGY IN A TREAT-AND-EXTEND REGIMEN FOR EXUDATIVE AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To evaluate the outcome of an exit strategy in a treat-and-extend regimen for neovascular age-related macular degeneration. METHODS: Five hundred and ninety-eight eyes of 488 patients with neovascular age-related macular degeneration receiving intravitreal anti-vascular endothelial growth factor injections according to a treat-and-extend regimen were included in this retrospective study. A treat-and-extend regimen with either interval extension by 2 weeks or shortening by 1 week was used. "Exit criteria" were defined as 3 consecutive injections 16 weeks apart with stable findings after which the patient was exited from treatment and followed up at 3 to 4 monthly intervals without therapy. Best-corrected visual acuity, central retinal thickness at treatment initiation and termination, incidence of recurrence after treatment termination, presence of characteristics in the optical coherence tomography, duration of therapy, number and intervals of injections were analyzed. RESULTS: Seventeen percent of all included eyes met the exit criteria. The mean number of anti-vascular endothelial growth factor injections was 23.7 ± 14.7 with a mean treatment duration of 4.5 ± 2.5 years. Twelve percent reached exit with the minimal number of injections. Thirteen percent had recurrent disease after a mean of 37 ± 16 weeks. In the subgroup with recurrent disease, rate of pigment epithelial detachment at treatment termination was significantly higher than without recurrence (77% vs. 30%, P = 0.0018) with a significant higher proportion of serous pigment epithelial detachment (31% vs. 7%, P = 0.0247). CONCLUSION: The high percentage of patients meeting the exit criteria and the relatively low incidence of recurrences underline the usefulness of a predefined exit strategy. However, in a subgroup of patients, continuation of therapy may be advisable.

RETINAL FLECKS IN STARGARDT DISEASE REVEAL CHARACTERISTIC FLUORESCENCE LIFETIME TRANSITION OVER TIME.

PURPOSE: Stargardt disease is the most common inherited juvenile macular dystrophy and is characterized by yellowish flecks across the posterior pole. The purpose of this study was to investigate fluorescence lifetime changes of retinal flecks over time using fluorescence lifetime imaging ophthalmoscopy. METHODS: Longitudinal fluorescence lifetime data of 12 patients with Stargardt disease (mean age ± SEM, 42.25 ± 2.1 years; range, 28-58 years) were acquired using a fluorescence lifetime imaging ophthalmoscope based on a Heidelberg Engineering Spectralis system. Retinal autofluorescence was excited with a 470-nm laser. The emitted fluorescence was detected in two wavelength channels: a short spectral channel (498-560 nm) and a long spectral channel (560-720 nm). The mean retinal autofluorescence lifetimes were calculated and further analyzed with corresponding color fundus images, autofluorescence intensity images, and spectral domain optical coherence tomography. Patients were classified into three subtypes. RESULTS: All patients with Stargardt disease displayed characteristic autofluorescence lifetime patterns. Mean fluorescence lifetime values within areas of yellow flecks were significantly prolonged (long spectral channel 484 ps) compared with the surrounding tissue (long spectral channel 297 ps). In 91.6% of the eyes, flecks with short fluorescence lifetimes (long spectral channel 255 ps) were identified. Short lifetime flecks progressed to flecks with characteristic long lifetimes in 75.1% of eyes within a mean interval of 29.2 months (range 3-45 months). Between baseline and follow-up, the rate of newly developed short lifetime flecks (number/per year) based on subtypes was 2.62 in Group 1, 1.43 in Group 2, and 0.81 in Group 3. CONCLUSION: Recent onset flecks in Stargardt disease display short fluorescence lifetimes and convert into longer fluorescence lifetime flecks over time. This transition may represent a change in the composition of retinal deposits with accumulation of lipofuscin and retinoid by-products from the visual cycle. With emerging treatment options, these findings may prove useful to monitor disease progression and therapeutic effects.

VASCULAR ABNORMALITIES IN DIABETIC RETINOPATHY ASSESSED WITH SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY WIDEFIELD IMAGING.

PURPOSE: To detect vascular abnormalities in diabetic retinopathy using swept-source optical coherence tomography angiography (SS-OCTA) widefield images, and to compare the findings with color fundus photographs (CFPs) using Early Treatment Diabetic Retinopathy Study severity grading. METHODS: 3 mm × 3 mm and 12 mm × 12 mm scans were acquired to cover 70° to 80° of the posterior pole using a 100-kHz SS-OCTA instrument. Two masked graders assessed the presence of vascular abnormalities on SS-OCTA and the Early Treatment Diabetic Retinopathy Study level on CFP. The grading results were then compared. RESULTS: A total of 120 diabetic eyes (60 patients) were imaged with the SS-OCTA instrument. Cohort 1 (91 eyes; SS-OCTA grading only) showed microaneurysms in 91% (n = 83), intraretinal microvascular abnormalities in 79% (n = 72), and neovascularization in 21% (n = 19) of cases. Cohort 2 (52 eyes; CFP grading compared with SS-OCTA) showed microaneurysms on CFP in 90% (n = 47) and on SS-OCTA in 96% (n = 50) of cases. Agreement in intraretinal microvascular abnormality detection was fair (k = 0.2). Swept-source optical coherence tomography angiography detected 50% of intraretinal microvascular abnormality cases (n = 26), which were missed on CFP. Agreement in detecting neovascularization was moderate (k = 0.5). CONCLUSION: Agreement in detection of diabetic retinopathy features on CFP and SS-OCTA varies depending on the vascular changes examined. Swept-source optical coherence tomography angiography shows a higher detection rate of intraretinal microvascular abnormalities (P = 0.039), compared with Early Treatment Diabetic Retinopathy Study grading.