Soluble vascular endothelial growth factor receptor-2 and inflammatory factors in macular edema with branch retinal vein occlusion

Visual Acuity and Retinal Thickness and Sensitivity after Intravitreal Ranibizumab Injection for Macular Edema in Branch Retinal Vein Occlusion

Background/Objectives: To investigate changes in visual acuity and retinal sensitivity and thickness after intravitreal ranibizumab injection (IRI) for macular edema in branch retinal vein occlusion (BRVO) patients. Methods: This study evaluated 34 patients with treatment-naïve BRVO and at least 6 months' follow-up after pro re nata IRI. Best-corrected visual acuity (BCVA) was determined as the logarithm of the minimum angle of resolution (logMAR). In nine retinal regions, retinal sensitivity was calculated by MP-3 microperimetry; and in nine macular subfields, retinal thickness was measured by optical coherence tomography (OCT); evaluations were performed before IRI and then monthly for 6 months. Results: IRI significantly improved visual acuity and retinal sensitivity and thickness. In patients with good improvement in BCVA (change in logMAR > 0.2), IRI significantly improved retinal sensitivity in eight of nine regions, i.e., in all except the outer non-occluded region, and in patients with poor improvement in BCVA (change in logMAR < 0.2), in six of nine regions, i.e., not in the inner, outer non-occluded, and outer temporal regions. We found significant differences in the trend profile in the foveal, outer occluded, and inner nasal regions between patients with good and poor improvement in BCVA. Conclusions: The findings suggest that IRI improves visual acuity and retinal sensitivity and thickness and that retinal effects may vary between patients with good and poor visual improvement.

Role of Novel Inflammatory Factors in Central Retinal Vein Occlusion with Macular Edema

Background and Objectives: To investigate associations among the aqueous humor levels of novel inflammatory factors, including FMS-related tyrosine kinase 3 ligand (Flt-3L), fractalkine, CXC chemokine ligand 16 (CXCL-16), and endocan-1; the severity of macular edema in central retinal vein occlusion (CRVO); and the prognosis of CRVO with macular edema after antivascular endothelial growth factor (VEGF) therapy. Materials and Methods: Aqueous humor was obtained during anti-VEGF treatment with intravitreal ranibizumab injection (IRI) in patients with CRVO and macular edema (n = 19) and during cataract surgery in patients with cataracts (controls, n = 20), and the levels of VEGF and novel inflammatory factors were measured. Macular edema was evaluated by central macular thickness (CMT) and neurosensory retinal thickness (TNeuro), and improvement was evaluated by calculating the percentage change in CMT and TNeuro from before to 1 month after IRI. Results: The levels of VEGF and the novel inflammatory factors were significantly higher in the CRVO group, and the levels of Flt-3L, CXCL-16, and endocan-1 were significantly correlated with each other and with the aqueous flare value. Baseline levels of Flt-3L, CXCL-16, and endocan-1 had a significantly negative correlation with the change in CMT, and the baseline level of CXCL-16 was significantly negatively correlated with the change in TNeuro. Conclusions: Relations among novel inflammatory factors should be further investigated. These findings may help improve understanding of macular edema in CRVO patients and aid the development of new treatments targeting novel inflammatory factors.

Anti-Vascular Endothelial Growth Factor Therapy with or Without Initial Steroid Therapy for Macular Edema in Branch Retinal Vein Occlusion

Purpose

In branch retinal vein occlusion (BRVO), administering steroid injections to inhibit expression of inflammatory factors in the first phase of macular edema may reduce recurrence of the edema. The purpose of our study was to investigate the functional and morphological prognosis and frequency of recurrence after injection of an anti-vascular endothelial growth factor (VEGF) with and without initial steroid therapy to treat macular edema with BRVO.

Patients and Methods

Patients with BRVO and macular edema (41 eyes) received intravitreal ranibizumab injection (IRI) alone (IRI group, 21 eyes) or subtenon triamcinolone (STTA) injection and IRI (combination group, 20 eyes). Patients in both groups with recurrent macular edema received further IRI as appropriate. A laser flare meter was used to assess aqueous flare values, and an optical coherence tomography device was used to measure central macular thickness (CMT). Before the first treatment, we obtained samples of aqueous humor and analyzed them by the suspension array method to evaluate VEGF, placental growth factor (PlGF), platelet-derived growth factor (PDGF)-AA, soluble intercellular adhesion molecule (sICAM)-1, monocyte chemoattractant protein 1 (MCP-1), interleukin (IL)-6, IL-8, and interferon-inducible 10-kDa protein (IP-10).

Results

The two groups were not significantly different with regard to levels of VEGF, PlGF, PDGF-AA, sICAM-1, MCP-1, IL-6, IL-8, or IP-10. Best-corrected visual acuity, CMT, and aqueous flare value (IRI group, baseline 8.69 ± 4.55 photon counts/ms; combination group, baseline 9.21 ± 3.72 photon counts/ms) improved significantly in both groups without significant intergroup differences. Analyses showed no significant intergroup differences in the mean number of IRIs during the 12-month follow-up, but the proportion of patients without recurrence (ie, who received only one IRI) was significantly higher in the combination group than in the IRI group (P = 0.032). Furthermore, the time to initial recurrence was significantly longer in the combination group than in the IRI group (P = 0.003).

Conclusion

These findings suggest that initial STTA injection and IRI may have a synergistic effect in patients with BRVO and macular edema in that they increase the time between anti-VEGF treatments.

Effects of Intravitreal Ranibizumab Injection on Peripheral Retinal Microcirculation and Cytokines in Branch Retinal Vein Occlusion with Macular Edema

Background and Objectives: To investigate peripheral blood flow in retinal vessels and vessel diameters after intravitreal ranibizumab injection (IRI) and the relationship between these parameters and cytokines in branch retinal vein occlusion (BRVO) with macular edema. Materials and Methods: We assessed relative flow volume (RFV) and the width of the main and branch retinal arteries and veins in the occluded and non-occluded regions before and after IRI in 37 patients with BRVO and macular edema. Measurements were made using laser speckle flowgraphy (LSFG). When performing IRI, we obtained samples of aqueous humor and analyzed them using the suspension array method to evaluate vascular endothelial growth factor (VEGF), placental growth factor (PlGF), platelet-derived growth factor (PDGF)-AA, soluble intercellular adhesion molecule (sICAM)-1, monocyte chemoattractant protein 1 (MCP-1), interleukin (IL)-6, IL-8, and interferon-inducible 10-kDa protein (IP-10). Results: In both retinal regions, before and after IRI, the RFV in the main artery and vein showed a significant correlation with the summed RFV in the respective branch vessels 1 and 2. In the occluded region, the RFV in the main vein was significantly negatively correlated with MCP-1, PDGF-AA, IL-6, and IL-8; the RFV in branch vein 1 was significantly negatively correlated with PlGF, MCP-1, IL-6, and IL-8; PDGF-AA was significantly negatively correlated with the width of the main and branch veins; and the RFVs of the main artery and vein decreased significantly from before to 1 month after IRI. Conclusions: Contrary to expectations, the study found that anti-VEGF therapy does not affect RFV in arteries and veins in patients with BRVO and macular edema. Furthermore, retinal blood flow is poor in patients with high MCP-1, IL-6, and IL-8. Finally, high PDGF-AA may result in smaller venous diameters and reduced retinal blood flow.

A Review of Intraocular Biomolecules in Retinal Vein Occlusion: Toward Potential Biomarkers for Companion Diagnostics

Retinal vein occlusion (RVO) is one of the most common retinal vascular diseases. The pathogenesis of RVO is multifactorial and involves a complex interplay among a variety of vascular and inflammatory mediators. Many cytokines, chemokines, growth factors, and cell adhesion molecules have been reported to be implicated. Treatments for RVO are directed at the management of underlying risk factors and vision-threatening complications, including macula edema (ME) and neovascularization. Intravitreal anti-VEGF agents are currently considered as the first-line treatment for ME secondary to RVO (RVO-ME), but a substantial proportion of patients responded insufficiently to anti-VEGF agents. Since RVO-ME refractory to anti-VEGF agents generally responds to corticosteroids and its visual outcome is negatively correlated to disease duration, prediction of treatment response at baseline in RVO-ME may significantly improve both cost-effectiveness and visual prognosis. Several bioactive molecules in the aqueous humor were found to be associated with disease status in RVO. This review aims to present a comprehensive review of intraocular biomolecules reported in RVO, including VEGF, IL-6, IL-8, MCP-1, sICAM-1, IL-12, IL-13, sVEGFR-1, sVEGFR-2, PDGF-AA, etc., highlighting their association with disease severity and/or phenotype, and their potential roles in prognostic prediction and treatment selection. Some of these molecules may serve as biomarkers for aqueous humor-based companion diagnostics for the treatment of RVO in the future.

Real-Life Management of Central and Branch Retinal Vein Occlusion: A Seven-Year Follow-Up Study

Retinal vein occlusion is the second most common retinal vascular pathology after diabetic retinopathy and a major cause of vision impairment. Nowadays, both central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) can be well-managed by intravitreal treatments. However, considering the long-life expectance of the patients, few data are present in the literature about the very long-term outcome of CRVO and BRVO. The present study was an interventional, retrospective analysis of the morphological and functional long-term outcome of CRVO and BRVO patients, followed in an Italian referral center. We collected data from 313 eyes (178 CRVO eyes and 135 BRVO eyes). Mean follow-up was 45 ± 25 months (range 12-84 months). Both CRVO and BRVO eyes experience a significant visual acuity improvement secondary to anti-vascular endothelial growth factor/dexamethasone treatments (from 0.57 ± 0.25 to 0.41 ± 0.24 LogMAR in CRVO and from 0.53 ± 0.42 to 0.30 ± 0.41 LogMAR in BRVO, respectively) (p < 0.01). Also, central macular thickness (CMT) resulted significant recovery at the end of the follow-up (from 585.54 ± 131.43 to 447.88 ± 245.07 μm in CRVO and from 585.54 ± 131.43 to 447.88 ± 245.07 μm in BRVO, respectively) (p < 0.01). CRVO eyes received a mean of 10.70 ± 4.76 intravitreal treatments, whereas BRVO underwent 9.80 ± 5.39 injections over the entire 7-year follow-up. Our analyses highlighted different time points indicating the best obtainable improvement. This was the first year for CRVO (12-month follow-up) and the second year for BRVO (24-month follow-up). After these two time points, both visual acuity and CMT resulted stable up to the end of the follow-up. Ischemia was associated with significantly worse outcome.

Multimodal Imaging of Microvascular Abnormalities in Retinal Vein Occlusion

The technologies of ocular imaging modalities such as optical coherence tomography (OCT) and OCT angiography (OCTA) have progressed remarkably. Of these in vivo imaging modalities, recently advanced OCT technology provides high-resolution images, e.g., histologic imaging, enabling anatomical analysis of each retinal layer, including the photoreceptor layers. Recently developed OCTA also visualizes the vascular networks three-dimensionally, which provides better understanding of the retinal deep capillary layer. In addition, ex vivo analysis using autologous aqueous or vitreous humor shows that inflammatory cytokine levels including vascular endothelial growth factor (VEGF) are elevated and correlated with the severity of macular edema (ME) in eyes with retinal vein occlusion (RVO). Furthermore, a combination of multiple modalities enables deeper understanding of the pathology. Regarding therapy, intravitreal injection of anti-VEGF drugs provides rapid resolution of ME and much better visual improvements than conventional treatments in eyes with RVO. Thus, the technologies of examination and treatment for managing eyes with RVO have progressed rapidly. In this paper, we review the multimodal imaging and therapeutic strategies for eyes with RVO with the hope that it provides better understanding of the pathology and leads to the development of new therapies.

Intravitreal Dexamethasone Implant as a Sustained Release Drug Delivery Device for the Treatment of Ocular Diseases: A Comprehensive Review of the Literature

Drug delivery into the vitreous chamber remains a great challenge in the pharmaceutical industry due to the complex anatomy and physiology of the eye. Intravitreal injection is the mainstream route of drug administration to the posterior segment of the eye. The purpose of this review is to assess the current literature about the widening use of the intravitreal 0.7 mg dexamethasone (Dex) implant, and to provide a comprehensive collection of all the ocular disorders that benefit from Dex administration. Although anti-vascular endothelial growth-factors (VEGFs) have been largely indicated as a first-choice level, the Dex implant represents an important treatment option, especially in selected cases, such as vitrectomized eyes or patients in whom anti-VEGF failed or are contraindicated. In this article, the safety profile as well as the list of the possible complications related to intravitreal Dex injection are also discussed.

Changes in Aqueous and Vitreous Inflammatory Cytokine Levels in Retinal Vein Occlusion: A Systematic Review and Meta-analysis

Purpose:

Evidence suggests that inflammatory cytokines not only play a role in the pathogenesis of retinal vein occlusion (RVO) but also may be useful as biomarkers to predict disease severity and response to treatment. We aimed to quantitatively summarize data on inflammatory cytokines associated with RVO.

Methods:

A systematic search of peer-reviewed English-language articles was performed without year limitation up to August 19, 2019. Studies were included if they provided data on aqueous or vitreous cytokine concentrations in patients with RVO. Data were extracted from 116 studies that encompassed 3242 study eyes with RVO and 1402 control eyes. Effect sizes were generated as standardized mean differences (SMDs) of cytokine concentrations between patients with RVO vs controls.

Results:

Among the 4644 eyes in 116 studies, aqueous and vitreous concentrations (SMD, 95% CI, and P value) of interleukin (IL)-6 (aqueous: 1.23, 0.65 to 1.81, P < .001 vitreous: 0.70, 0.49 to 0.90, P < .001), IL-8 (aqueous: 1.11, 0.73 to 1.49, P < .001; vitreous: 1.19, 0.73 to 1.65, P < .001), monocyte chemoattractant protein 1(aqueous: 1.22, 0.72 to 1.72, P < .001; vitreous 1.42, 0.92 to 1.91, P < .001), vascular endothelial growth factor (VEGF) (aqueous: 1.52, 1.09 to 1.94, P < .001; vitreous: 0.99, 0.78 to 1.21, P < .001) were significantly higher in patients with RVO than in healthy controls. Only aqueous concentrations of IL-10 (0.81, 0.45 to 1.18, P < .001), angiopoietin 4 (1.96, 0.92 to 3.00, P < .001), and platelet-derived growth factor (PDGF)-AA (0.82, 0.35 to 1.30, P < .001) were significantly higher in patients with RVO than in healthy controls. Only the vitreous concentration of soluble intercellular adhesion molecule-1 (sICAM-1) (1.23, 0.83 to 1.63, P < .001) was significantly higher in patients with RVO. No differences, failed sensitivity analyses, or insufficient data were found between patients with RVO and healthy controls for the concentrations of the remaining cytokines.

Conclusions:

Several cytokines in addition to VEGF have the potential to be useful biomarkers and therapeutic targets in RVO.

Current Outcomes of Anti-VEGF Therapy in the Treatment of Macular Oedema Secondary to Branch Retinal Vein Occlusions: A Meta-Analysis

PURPOSE

The current body of evidence on the efficacy and safety of anti-VEGFs for macular oedema secondary to branch retinal vein occlusion (BRVO) is steadily growing as large clinical trials and observational studies are continually completed. The aim of this meta-analysis is to analyse anatomical and functional outcomes in response to anti-VEGF therapy using evidence generated from a pooled analysis of current clinical trials and observational studies.

METHODS

The current meta-analysis includes treatment of BRVO with aflibercept, bevacizumab and ranibizumab from randomised controlled trials and observational studies. Inclusion criteria included peer-reviewed publications with at least a 12-month follow-up period. On literature review using multiple electronic databases (PubMed, Embase and Cochrane), 22 studies met the inclusion criteria. Baseline patient characteristics, study design, sample size and 12- and 24-month change in best corrected visual acuity (BCVA) and central foveal thickness (CFT) as measured on optical coherence tomography imaging were pooled in a meta-analysis. Data were then stratified by study design and anti-VEGF therapy in subgroup analyses.

RESULTS

A total of 1,236 eyes from 22 studies were included in this meta-analysis. Mean baseline BCVA ranged from 66 ETDRS letters (20/50 Snellen equivalent) to 35 letters (20/200 Snellen). Mean baseline CFT ranged from 406.0 to 681.0 µm. Anti-VEGF treatment demonstrated an overall mean improvement in BCVA at 12 months of 14 letters (95% CI 12.0 to 16.2, p < 0.001) and CFT reduction of 228 µm (95% CI -278.9 to -176.1, p < 0.001). The BCVA gains at 12 months were maintained to month 24 with a mean gain of 12.5 letters (95% CI 6.3 to 18.8, p < 0.001), as well as reduction of CFT of 238 µm (95% CI -336.0 to -140.2, p < 0.001). No cases of endophthalmitis or glaucoma were reported in any study.

CONCLUSION

This meta-analysis confirms the comparable safety and efficacy of anti-VEGF therapies for patients with cystoid macular oedema secondary to BRVO. There is a need for randomised prospective comparative trials of anti-VEGF agents for BRVO.

Efficacy and safety of dexamethasone intravitreal implant in patients with retinal vein occlusion resistant to anti-VEGF therapy: a 12-month prospective study

Purpose: To evaluate the safety and efficacy of repeated intravitreal dexamethasone implant (Ozurdex) injections administrated on an "as-needed" protocol for retinal vein occlusion patients with macular oedema, previously subjected to at least five anti-vascular endothelial growth factor (VEGF) injections with poor or no response. Methods: Prospective interventional case series of 13 branch retinal vein occlusion (BRVO) and 10 central retinal vein occlusion (CRVO) patients with persistent macular oedema (>250 μm) after at least five anti-VEGF injections. Exclusion criteria included: baseline visual acuity worse than 1.5 logMAR, previous intravitreal implant, history of vitreoretinal surgery, manifest glaucoma or ocular hypertension, epiretinal membrane, retinal neovascularization, massive retinal or macular ischaemia, vitreous haemorrhage or severe lens opacity, previous laser photocoagulation treatment. Each patient received an initial intraocular dexamethasone implant and the procedure was repeated at 6 months "as needed." Patients were followed up at months 2, 4, 6, 8, 10 and 12 with spectral domain optical coherence tomography and best corrected visual acuity measurements. Exclusion criteria included: baseline visual acuity worse than 1.5 logMAR, previous intravitreal implant, history of vitreoretinal surgery, manifest glaucoma or ocular hypertension, epiretinal membrane, retinal neovascularization, retinal or macular ischaemia, vitreous haemorrhage or severe lens opacity, previous laser photocoagulation treatment. Patients on topical or systemic corticosteroid therapy (during the last 3 months), and known steroid responders as well as diabetic patients were also excluded. Results: In the BRVO group, the mean central retinal thickness (CRT) and best corrected visual acuity (BCVA) significantly improved from 482.92 ± 139.99 μm (0.55 ± 0.12 logMAR) at baseline, to 369.31 ± 119.72 μm (0.43 ± 0.18 logMAR) at 6 months (p = 0.011/p = 0.019). At 12 months CRT was 295.82 ± 135.48 μm (p = 0.026) and BCVA 0.29 ± 0.17 logMAR (p = 0.002). Minimum CRT values were achieved at 3.45 months after the first injection, and 2.46 months after the second injection (197.00 ± 84.27 and 180.00 ± 76.89 μm, respectively). Best BCVA values were achieved at a mean of 4 ± 0.853 months after the first injection, and 4 months after the second injection (0.219 ± 0.129 and 0.222 ± 0.078 logMAR, respectively). In the CRVO group, neither the mean CRT nor BCVA improved significantly at 6 months: from 669.70 ± 203.20 μm (0.80 ± 0.231 logMAR) at baseline, to 586.20 ± 237.63 μm (0.740 ± 0.268 logMAR) at 6 months (p = 0.131/p = 0.333). At 12 months CRT was significantly improved: 549.90 ± 191.26 μm (p = 0.047), but BCVA lacked significant improvement: 0.690 ± 0.285 logMAR (p = 0.072). Minimum CRT values were achieved at a mean of 2 months after the first injection, and also 2 months after the second injection (261.60 ± 121.31 and 280.00 ± 177.43 μm, respectively). Best BCVA values were achieved at a mean of 2 months after the first injection, and 2 months after the second injection and were 0.390 ± 0.173 and 0.385 ± 0.233 logMAR, respectively. Cataract progression was a rare event (2/23 eyes), while transient steroid-induced ocular hypertension (5/23 eyes) was managed successfully with IOP-lowering medication Conclusion: Dexamethasone implant should be considered as an effective and safe alternative in patients with BRVO and CRVO who have failed anti-VEGF therapy. Shortening the re-injection interval especially for CRVO cases should be considered.

Cytokines and the Pathogenesis of Macular Edema in Branch Retinal Vein Occlusion

Branch retinal vein occlusion (BRVO) is a very common retinal vascular problem in patients with lifestyle-related diseases, such as hypertension and arteriosclerosis. In patients with BRVO, development of macular edema is the main cause of visual impairment. BRVO is still a controversial condition in many respects. Over the years, various methods such as laser photocoagulation have been tried to treat macular edema associated with BRVO, but the results were not satisfactory. After vascular endothelial growth factor (VEGF) was found to have an important role in the pathogenesis of macular edema in BRVO patients, treatment of this condition was revolutionized by development of anti-VEGF therapy. Although macular edema improves dramatically following intraocular injection of anti-VEGF agents, repeated recurrence and resistance of edema is a major problem in some BRVO patients. This suggests that factors or cytokines other than VEGF may be associated with inflammation and retinal hypoxia in BRVO and that the pathogenesis of macular edema is complicated. The present review assesses the role of various factors and cytokines in the pathogenesis of macular edema associated with BRVO. We present a mechanism that is not only plausible but should also be useful for developing new therapeutic strategies.

Dexamethasone intravitreal implant downregulates PDGFR-α and upregulates caveolin-1 in experimental branch retinal vein occlusion

A dexamethasone (DEX) intravitreal implant (OZURDEX) provides an effective treatment of inflammation secondary to branch retinal vein occlusion (BRVO). Retinal proteome changes which mediate the beneficial effects of the implant remain poorly understood. To study retinal proteome changes in BRVO following an intervention with a DEX implant this study combined an experimental model of BRVO with proteomic techniques. In eight Danish Landrace pigs experimental BRVO was induced in both eyes using argon laser. After inducing BRVO a DEX implant was injected into the right eye of each animal while the left control eye was given an identical injection without an implant. Fifteen days after BRVO and DEX implant intervention the retinas were excised and analyzed with tandem mass tag based mass spectrometry. A total of 26 significantly changed proteins were identified. DEX intervention reduced the retinal levels of platelet-derived growth factor receptor-α (PDGFR-α) and vascular endothelial growth factor receptor 2 (VEGFR-2). DEX treatment resulted in increased levels of caveolin-1, peptidyl-prolyl cis-trans isomerase FKBP5 and transgelin. Changes in PDGFR-α and caveolin-1 were confirmed with immunohistochemistry. In BRVO treated with the DEX implant a strong reaction for caveolin-1 was observed in the innermost retinal layers. DEX implant intervention may inhibit PDGF signaling by decreasing the retinal level of PDGFR-α while an increased content of caveolin-1 may help maintain the integrity of the blood-retinal barrier.

One-year outcomes of ziv-aflibercept for macular edema in central retinal vein occlusion

Purpose

To report the 12-month efficacy and safety outcomes of intravitreal ziv-aflibercept in macular edema secondary to central retinal vein occlusion (CRVO).

Methods

Interventional case series documenting 12-month outcomes of intravitreal ziv-aflibercept (1.25 mg in 0.05 mL) in 6 patients with treatment-naive macular edema secondary to CRVO. All patients had comprehensive ophthalmic examination, spectral domain optical coherence tomography at baseline and all follow-up visits, and fluorescein. Retreatment decisions were based on recurrence or persistence of intraretinal or subretinal fluid, deterioration in visual acuity (VA), increase in central subfield thickness (CST) by ≥ 50 μm from the previous visit, or lowest recorded CST.

Results

Participants had (2 males, 4 females) an average age of 53.5 years. From baseline to 12 months, the mean logMAR VA improved from 0.86 (Snellen ≈ 20/145) to 0.33 (Snellen ≈ 20/40), central macular thickness decreased from 519 μm to 255 μm, and total macular volume decreased from 14.7 mm³ to 7.1 mm³. No eyes had uveitis, cataract progression, intraocular pressure (IOP) elevations, or systemic adverse events.

Conclusions and importance

Ziv-aflibercept achieves favorable intermediate-term functional and structural outcomes in macular edema secondary to CRVO. No safety concerns were raised. Low-cost ziv-aflibercept may thus be useful for CRVO in resource-poor countries. Further prospective studies in larger cohorts are needed further establish the efficacy and safety of this agent.

A Review: Proteomics in Retinal Artery Occlusion, Retinal Vein Occlusion, Diabetic Retinopathy and Acquired Macular Disorders

Retinal artery occlusion (RAO), retinal vein occlusion (RVO), diabetic retinopathy (DR) and age-related macular degeneration (AMD) are frequent ocular diseases with potentially sight-threatening outcomes. In the present review we discuss major findings of proteomic studies of RAO, RVO, DR and AMD, including an overview of ocular proteome changes associated with anti-vascular endothelial growth factor (VEGF) treatments. Despite the severe outcomes of RAO, the proteome of the disease remains largely unstudied. There is also limited knowledge about the proteome of RVO, but proteomic studies suggest that RVO is associated with remodeling of the extracellular matrix and adhesion processes. Proteomic studies of DR have resulted in the identification of potential therapeutic targets such as carbonic anhydrase-I. Proliferative diabetic retinopathy is the most intensively studied stage of DR. Proteomic studies have established VEGF, pigment epithelium-derived factor (PEDF) and complement components as key factors associated with AMD. The aim of this review is to highlight the major milestones in proteomics in RAO, RVO, DR and AMD. Through large-scale protein analyses, proteomics is bringing new important insights into these complex pathological conditions.

Retinal proteome changes following experimental branch retinal vein occlusion and intervention with ranibizumab

Animal models of experimental branch retinal vein occlusion (BRVO) provide a unique opportunity to study protein changes directly in retinal tissue. Results from these experimental models suggest that experimental BRVO is associated with an upregulation of extracellular matrix remodeling and adhesion signaling processes. To study whether these processes could be blocked by inhibition of VEGF-A, a porcine model of experimental BRVO was combined with proteomic analyses. In six Danish Landrace pigs experimental BRVO was induced with argon laser in both eyes. After 24 h an injection of 0.05 mL ranibizumab was given in the right eyes of the animals while left eyes received an injection of 0.05 mL 9 mg/mL sodium chloride water. Retinas were dissected three days after BRVO and the retinal samples were analyzed with label-free quantification as well as tandem mass tag based proteomics. In retinas treated with ranibizumab five proteins exhibited statistically significant changes in content with both proteomic techniques. These five proteins, which were all decreased in content, included integrin β-1, peroxisomal 3-ketoacyl-CoA thiolase, OCIA domain-containing protein 1, calnexin and 40S ribosomal protein S5. As anti-integrin therapies are under development for inhibition of angiogenesis in retinal diseases it is interesting that inhibition of VEGF-A in itself resulted in a small decrease in the content of integrin β-1. The decreased content of integrin β-1 indicates that extracellular matrix remodeling and adhesion processes associated with BRVO are at least partly reversed through inhibition of VEGF-A.

Intravitreal Aflibercept for Macular Edema Following Branch Retinal Vein Occlusion: 52-Week Results of the VIBRANT Study

PURPOSE

To determine week 52 efficacy and safety outcomes in eyes with macular edema after branch retinal vein occlusion (BRVO) treated with 2 mg intravitreal aflibercept injection (IAI) compared with grid laser.

DESIGN

VIBRANT was a double-masked, randomized, phase 3 trial.

PARTICIPANTS

Eyes randomized and treated in VIBRANT were followed to week 52.

METHODS

In the IAI group, eyes received IAI every 4 weeks through week 24 and IAI every 8 weeks through week 48 with rescue grid laser if needed at week 36. In the grid laser group, all eyes received grid laser at baseline and, if prespecified rescue criteria were met, 1 additional laser from week 12 to 20 and IAI every 8 weeks after 3 monthly doses from week 24 onward (the laser/IAI group).

MAIN OUTCOME MEASURES

The primary outcome measure was percentage of eyes with improvement from baseline best-corrected visual acuity (BCVA) letter score ≥15 at week 24. All outcome measures at week 52 were exploratory, and P values are considered nominal.

RESULTS

The percentage of eyes with improvement from baseline letter score ≥15 in the IAI and laser/IAI groups was 52.7% versus 26.7% (P = 0.0003) at week 24 and 57.1% versus 41.1% (P = 0.0296) at week 52. The corresponding mean change from baseline BCVA letter score was 17.0 versus 6.9 (P < 0.0001) at week 24 and 17.1 versus 12.2 (P = 0.0035) at week 52. The mean reduction from baseline central retinal thickness was 280.5 μm versus 128.0 μm (P < 0.0001) at week 24 and 283.9 μm versus 249.3 μm (P = 0.0218) at week 52. In the IAI group, 10.6% of eyes received rescue laser at week 36, and in the laser/IAI group, 80.7% received rescue IAI from week 24 to week 48. Traumatic cataract in 1 eye (1.1%) in the IAI group was the only ocular serious adverse event.

CONCLUSIONS

After 6 monthly IAI, injections every 8 weeks maintained control of macular edema and visual benefits through week 52. In the laser group, rescue IAI given from week 24 onward resulted in substantial visual improvements at week 52.

Vascular endothelial growth factor and its soluble receptors-1 and -2 in iris neovascularization and neovascular glaucoma

Concentrations of vascular endothelial growth factor (VEGF), soluble VEGF receptor-1 (sVEGFR-1) and soluble VEGF receptor-2 (sVEGFR-2) were measured by enzyme-linked immunosorbent assay in 27 proliferative diabetic retinopathy patients who had iris neovascularization (INV) with or without neovascular glaucoma (NVG). The 27 eyes were divided into two groups, consisting of INV without elevation of the intraocular pressure (IOP; INV group) and INV with elevated IOP (NVG group). Ten patients with an idiopathic macular hole were used as the controls. The vitreous levels of VEGF, sVEGFR-1 and sVEGFR-2 showed a significant increase across the three groups. In the INV and NVG groups, the vitreous level of VEGF showed a significant correlation with the levels of sVEGFR-1 and sVEGFR-2. There was also a significant correlation between the vitreous levels of sVEGFR-1 and sVEGFR-2. These results suggest that the vitreous levels of sVEGFR-1 and sVEGFR-2 are dependent on VEGF in patients who have INV with or without NVG.

Role of inflammation in previously untreated macular edema with branch retinal vein occlusion

BACKGROUND

The association of inflammatory factors and the aqueous flare value with macular edema in branch retinal vein occlusion (BRVO) patients remains unclear. The relationship between the aqueous flare value and the vitreous fluid levels of vascular endothelial growth factor (VEGF), interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, soluble intercellular adhesion molecule 1 (sICAM-1), and soluble VEGF receptor-2 (sVEGFR-2) was evaluated to investigate the role of inflammation in BRVO associated with macular edema. Aqueous flare values and the vitreous levels of VEGF, IL-6, MCP-1, sICAM-1, and sVEGFR-2 were compared between previously untreated patients with BRVO and patients with macular hole (MH).

METHODS

Vitreous samples were obtained from 45 patients during vitreoretinal surgery (28 patients with BRVO and 17 with MH), and the levels of VEGF, IL-6, MCP-1, sICAM-1, and sVEGFR-2 were measured by enzyme-linked immunosorbent assay. Retinal ischemia was evaluated by measuring the area of capillary non-perfusion using fluorescein angiography and the Scion Image program. Aqueous flare values were measured with a laser flare meter and macular edema was examined by optical coherence tomography.

RESULTS

The median aqueous flare value was significantly higher in the BRVO group (12.1 photon counts/ms) than in the MH group (4.5 photon counts/ms, P < 0.001). There were significant correlations between the aqueous flare value and the vitreous levels of VEGF, IL-6, MCP-1, and sICAM-1 in the BRVO group (ρ = 0.54, P = 0.005; ρ = 0.56, P = 0.004; ρ = 0.52, P = 0.006; and ρ = 0.47, P = 0.015, respectively). The aqueous flare value was also significantly correlated with the foveal thickness in the BRVO group (ρ = 0.40, P = 0.037).

CONCLUSIONS

Inflammation may induce an increase of vascular permeability and disrupt the blood-aqueous barrier via release of inflammatory factors (VEGF, IL-6, MCP-1, and sICAM-1) in BRVO patients with macular edema.

Aqueous soluble vascular endothelial growth factor receptor-2 in macular edema with branch retinal vein occlusion

PURPOSE/AIM

The aqueous humor level of soluble vascular endothelial growth factor receptor (sVEGFR)-2 may influence macular edema in patients with branch retinal vein occlusion (BRVO). The association of sVEGFR-2 with macular edema was investigated in this study.

MATERIALS AND METHODS

A retrospective case-controlled study was performed in 22 patients with BRVO and macular edema, as well as 5 patients with non-ischemic ocular diseases as the control group. The severity of macular edema was examined by optical coherence tomography. Aqueous humor samples were obtained during intravitreous injection of anti-VEGF agents, triamcinolone acetonide, or combined vitrectomy and cataract surgery. sVEGFR-2 levels in aqueous humor were determined by enzyme-linked immunosorbent assay.

RESULTS

The aqueous humor level of sVEGFR-2 (median: 124.5 ng/ml) was significantly elevated in BRVO patients compared with the control group (78.1 pg/ml) (p = 0.010). In addition, the sVEGFR-2 level was correlated with the severity of macular edema (p = 0.033).

CONCLUSIONS

sVEGFR-2 may be involved in the pathogenesis of macular edema associated with BRVO. Measurement of aqueous humor sVEGFR-2 levels may be helpful for understanding the disease status in BRVO patients with macular edema.

Retinal oximetry

ABSTRACT.:

PURPOSE

Malfunction of retinal blood flow or oxygenation is believed to be involved in various diseases. Among them are retinal vessel occlusions, diabetic retinopathy and glaucoma. Reliable, non-invasive technology for retinal oxygen measurements has been scarce and most of the knowledge on retinal oxygenation comes from animal studies. This thesis describes human retinal oximetry, performed with novel retinal oximetry technology. The thesis describes studies on retinal vessel oxygen saturation in (1) light and dark in healthy volunteers, (2) central retinal vein occlusion, (3) branch retinal vein occlusion, (4) central retinal artery occlusion, (5) diabetic retinopathy, (6) patients undergoing glaucoma surgery and (7) patients taking glaucoma medication.

METHODS

The retinal oximeter (Oxymap ehf., Reykjavik, Iceland) is based on a fundus camera. An attached image splitter allows the simultaneous capture of four images of the same area of the fundus. Two images are used for further analysis, one acquired with 586 nm light and one with 605 nm light. Light absorbance of retinal vessels is sensitive to oxygen saturation at 605 nm but not at 586 nm. Measurement of reflected light at these wavelengths allows estimation of oxygen saturation in the main retinal vessels. This is performed with custom-made analysis software.

RESULTS

LIGHT AND DARK: After 30 min in the dark, oxygen saturation in retinal arterioles of healthy volunteers was 92 ± 4% (mean ± SD, n = 15). After 5 min in 80 cd/m(2) light, the arteriolar saturation was 89 ± 5%. The decrease was statistically significant (p = 0.008). The corresponding values for retinal venules were 60 ± 5% in the dark and 55 ± 10% in the light (p = 0.020). Similar results were found after alternating 5 min periods of darkness and light. In a second experiment (n = 19), a significant decrease in retinal vessel oxygen saturation was found in 100 cd/m(2) light compared with darkness but 1 and 10 cd/m(2) light had no significant effect. CENTRAL RETINAL VEIN OCCLUSION: In patients with central retinal vein occlusion, the mean saturation in affected retinal venules was 49 ± 12%, while the mean value for venules in the fellow eye was 65 ± 6% (mean ± SD, p = 0.003, n = 8). The retinal arteriolar saturation was the same in affected (99 ± 3%) and the unaffected (99 ± 6%) eyes. The venous oxygen saturation showed much variation between affected eyes. BRANCH RETINAL VEIN OCCLUSION: Median oxygen saturation in venules affected by branch retinal vein occlusion was 59% (range, 12-93%, n = 22), while it was 63% (23-80%) in unaffected venules in the affected eye and 55% (39-80%) in venules in the fellow eye. The difference was not statistically significant (p > 0.05). There was a significant difference between affected arterioles (median 101%; range, 89-115%) and unaffected arterioles (95%, 85-104%) in the affected eye (p < 0.05, n = 18). CENTRAL RETINAL ARTERY OCCLUSION: In a patient with a day's history of central retinal artery occlusion due to temporal arteritis, the mean arteriolar saturation was 71 ± 9% and 63 ± 9% in the venules. One month later, after treatment with prednisolone, the mean arteriolar saturation was 100 ± 4% and the venous saturation 54 ± 5%. DIABETIC RETINOPATHY: When compared with healthy volunteers (n = 31), patients with all categories of diabetic retinopathy had on average 7-10 percentage points higher saturation in retinal arterioles (p < 0.05 for all categories, n = 6-8 in each category). In venules, the saturation was 8-12 percentage points higher (p < 0.05 for all categories). GLAUCOMA SURGERY: Oxygen saturation in retinal arterioles increased by 2 percentage points on average (p = 0.046, n = 19) with surgery, which lowered intraocular pressure from 23 ± 7 mmHg (mean ± SD) to 10 ± 4 mmHg (p < 0.0001). No other significant changes were found (p ≥ 0.35). DORZOLAMIDE: A significant reduction of 3 percentage points was found in arterioles (p < 0.01) and venules (p < 0.05) when patients with glaucoma or ocular hypertension changed from dorzolamide-timolol combination eye drops to timolol alone (n = 6). No change was found in patients, who started on timolol and switched to the combination therapy (p > 0.05, n = 7).

CONCLUSIONS

Dual wavelength oximetry can be used to non-invasively measure retinal vessel oxygen saturation in health and disease. The results indicate that retinal vessel oxygen saturation is (1) increased in the dark, (2) lower in venules affected by central retinal vein occlusions, (3) variable in branch retinal vein occlusion, (4) lower in retinal arterioles in central retinal artery occlusion, (5) increased in diabetic retinopathy, (6-7) mildly affected by glaucoma surgery or dorzolamide.

Comparison of the efficacy of intravitreal triamcinolone acetonide for cystoid macular edema with versus without serous retinal detachment in branch retinal vein occlusion: influence on macular sensitivity and morphology

BACKGROUND

The influence of serous retinal detachment (SRD) on visual acuity, macular sensitivity, and macular thickness is unclear after intravitreal injection of triamcinolone acetonide (IVTA) for macular edema with branch retinal vein occlusion (BRVO).

METHODS

Twenty-one eyes of 21 BRVO patients with macular edema received IVTA. Patients were divided into two groups by optical coherence tomography findings: 11 patients who had cystoid macular edema (CME) with SRD (SRD (+) group) and 10 patients who had CME without SRD (SRD (-) group). Microperimetry was performed with a Micro Perimeter 1 before and at 3 and 6 months after IVTA. Macular thickness was measured by optical coherence tomography. We exchanged the superior and inferior regions to separate the regions into those with and without occlusion. As a result, the superior region was always the occluded region and the inferior region was non-occluded.

RESULTS

In both the SRD (-) group and the SRD (+) group, the mean macular thickness within the central 4° field and the 10° and 20° fields of the occluded region decreased significantly from baseline to 3 and 6 months after IVTA (all P <0.01). Visual acuity also improved significantly in both groups from baseline to 3 and 6 months after IVTA (both P <0.05). In both groups, the mean macular sensitivity (measured with by microperimetry) within the central 4° field and the 10° and 20° fields of the occluded region showed a significant increase from baseline to 3 and 6 months after IVTA (all P <0.05). The trend profiles of macular thickness within the 10° and 20° fields of the occluded region showed significant differences, but there were no significant differences with respect to the trend profiles of visual acuity and macular sensitivity within the central 4° field and the 10° and 20° fields of the occluded region.

CONCLUSIONS

These results suggest that IVTA may achieve more marked improvement of macular morphology in BRVO patients with SRD than in those without SRD, while this therapy may have a similar effect on macular function in BRVO patients with or without SRD.

Vascular endothelial growth factor receptor-2 in macular oedema with retinal vein occlusion

BACKGROUND

To evaluate the relationships among vitreous fluid levels of soluble vascular endothelial growth factor receptor-2 (sVEGFR-2), vascular endothelial growth factor (VEGF), and the severity of macular oedema secondary to branch retinal vein occlusion (BRVO).

METHODS

Twenty-five BRVO patients with macular oedema were enrolled. Vitreous fluid samples were obtained during vitreoretinal surgery to measure the levels of sVEGFR-2 and VEGF. Macular oedema was examined by optical coherence tomography.

RESULTS

The vitreous fluid levels of VEGF and sVEGFR-2 were significantly correlated with the severity of macular oedema (ρ = 0.54, p = 0.008 and ρ = 0.40, p = 0.047, respectively). The sVEGFR-2 × VEGF product was also significantly correlated with the severity of macular oedema (ρ = 0.62, p = 0.003).

CONCLUSIONS

The severity of macular oedema was more closely associated with sVEGFR-2 × VEGF than sVEGFR-2 or VEGF alone, suggesting that macular oedema in BRVO patients may be influenced by both VEGF and sVEGFR-2.

Inflammatory factors in major and macular branch retinal vein occlusion

Concentrations of inflammatory factors were measured in 40 patients with macular edema due to major branch retinal vein occlusion (BRVO) or macular BRVO who were treated by pars plana vitrectomy. Vitreous fluid levels of vascular endothelial growth factor (VEGF), soluble intercellular adhesion molecule-1 (sICAM-1), and pigment epithelium-derived factor (PEDF) were determined. Visual acuity and central macular thickness were significantly improved at 6 months in both groups. Vitreous fluid levels of VEGF and sICAM-1 were higher in the major BRVO group than the macular BRVO group, while the PEDF level was lower in the major group than the macular group. The mean visual acuity and central macular thickness at 6 months were not significantly different between the macular and major groups. In conclusion, patients with major BRVO had higher vitreous levels of inflammatory factors and lower vitreous levels of anti-inflammatory PEDF. Accordingly, regulating inflammatory factors might be more important in major BRVO than macular BRVO.