Medical treatment of retinal vein occlusions

Troxerutin Improves Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice

Screening potential compounds for improving ulcerative colitis (UC) from clinical medication is an effective strategy for drug repurposing. We applied bioinformatics and network pharmacology to the drug screening process in this study, which helped us to screen out troxerutin that could improve UC. Troxerutin belongs to flavonoids and is used clinically as an anticoagulant and thrombolytic agent. This study found a new pharmacological activity of troxerutin, that is, it had a significant improvement effect on UC in mice. Experimental results of in vitro and in vivo levels showed that troxerutin could effectively reduce the level of oxidative stress that caused damages in intestinal epithelial cells and colonic tissue, maintain the distribution and expression of tight junction-related proteins, and protect the barrier function of colon tissue. In addition to the oxidative stress, severe inflammatory response is also an important pathological factor that aggravates UC. However, troxerutin could reduce the infiltration of inflammatory cells in the colon tissue and decrease the expression of inflammation-related proteins and proinflammatory cytokines. Due to its antioxidant and anti-inflammatory effects, troxerutin inhibited the process of cell apoptosis in the colon tissue and relieved the degree of colonic fibrosis. Bioinformatics analysis showed that the ameliorating effect of troxerutin on UC was probably related to its network regulation of signaling pathways. In summary, we discovered a new pharmacological activity of the flavonoid troxerutin against UC, which is conducive to the expansion and application of flavonoids in the treatment of human diseases.

RETINAL VEIN OCCLUSIONS, FROM BASICS TO THE LATEST TREATMENT

PURPOSE

To review the pathophysiology, diagnosis, and updated treatments of retinal vein occlusions (RVOs).

METHODS

A review of the literature was performed, focusing on the epidemiology, pathophysiology, diagnosis, and treatments (including both medical and surgical treatments) of RVO. Based on this review, a comprehensive overview was provided regarding the topic of RVO and focused on recent treatment updates.

RESULTS

Retinal vein occlusions have an age- and sex-standardized prevalence of 5.20 per 1,000 for any RVO, 4.42 per 1,000 for branch RVO, 0.80 per 1,000 for central RVO. Worldwide, an estimated 16.4 million adults are affected by RVOs, with 2.5 million affected by central RVO and 13.9 million affected by branch RVO. Retinal vein occlusion is recognized as an important cause of blindness and the diagnostic approaches and treatment options for RVO are reviewed and reported. The current treatment options including medical treatments (bevacizumab, ranibizumab, aflibercept, triamcinolone, and dexamethasone implants) and surgical alternatives were reviewed and reported with summaries on the corresponding strength of evidence.

CONCLUSION

Despite the understanding of this disease entity, challenges persist in the long-term treatment of RVO-related complications and visual loss. This review provided a detailed summary on the rationality and efficacy of recently developed treatment regimes and evaluated the potential benefit of combination therapy.

Investigational drugs for retinal vein occlusion

INTRODUCTION

Retinal vein occlusion (RVO) is the second most common retinal vascular disorder. This multifactorial disease frequently leads to visual impairment. Some risk factors for RVO can be managed prophylactically. Given the complex physiopathology of RVO, most of the latest therapeutic strategies focus on secondary clinical features (such as macular oedema and neovascularization).

AREAS COVERED

This author reviews ongoing, prospective, open-label Phase I and Phase II clinical trials of novels treatments for RVO (primarily intravitreal steroids and anti-VEGF agents). Specifically, they review the pharmacokinetics, safety profile, study design and adverse events associated with innovative drugs in clinical development.

EXPERT OPINION

A number of innovative, early-phase clinical trials are based on combination therapy with an anti-VEGF agent and steroids. There is good evidence that early treatment of RVO has clinical benefits. Larger, randomized studies are now required for a better understanding of patient selection, treatment timing and dosing, and thus the optimized use of novel drugs and medical devices.

The influence of anti-VEGF therapy on present day management of macular edema due to BRVO and CRVO: a longitudinal analysis on visual function, injection time interval and complications

The purpose of this study was to evaluate the impact of intravitreal bevacizumab injections on the management and outcome of patients affected by retinal vein occlusions, their effectiveness on morphological and functional parameters, the modalities of long-term management and the need for additional laser treatment due to ischemic retinal evolution. Patients diagnosed with branch retinal vein occlusion (BRVO) or central retinal vein occlusion (CRVO) had a comprehensive work-up including complete ophthalmic examination, fluorangiography (FA), optical coherence tomography (OCT), visual field testing (VFT), microperimetry (MP), and laser flare photometry (LFP). In case of BRVO, intraocular bevacizumab injection was performed if significant macular edema/visual deficit was still present 3 months after onset of occlusion and injections were started at presentation in case of CRVO. Post-injection follow-up examination including best corrected visual acuity (BCVA), intraocular pressure (IOP), LFP, OCT, MP, and VFT were performed monthly and recorded at the end of follow-up. Follow-up FA was performed between 12 and 18 months after diagnosis. Injections were repeated in case of recurrence of a significant central macular edema. Patients were subdivided into 2 groups according to number of injections: 1-4 injections or more than 4 injections. The proportion of resolved cases (no recurrence after a minimum follow-up of 12 months) was calculated and correlated with number of injections. In patients needing sustained injections, management modalities were recorded. The proportion of patients having needed laser photocoagulation treatment because of significant ischemic signs was recorded. Fifty-one patients were diagnosed with retinal vein occlusion between 2006 and 2012 at the Centre for Specialized Ophthalmic Care (COS) in Lausanne, Switzerland. Forty-four had enough data and were included in the study. Nine eyes were affected by CRVO and 35 were affected by BRVO. Mean BCVA at presentation was 0.24 ± 0.2 and improved to 0.81 ± 0.38 (p < 0.01) at 48 months. MP improved from 184.9 ± 92 to 362.5 ± 56.2 (p < 0.01) at 42 months follow-up. The number of injections varied from 1 to 25 (mean 5.5 ± 5.43). 31/44 eyes received 1-4 injections (group 1) of which all were recurrence free, with a follow-up of at least 1 years in all. 13/44 eyes received more than 5 injections (group 2) with functional and morphological parameters maintained in 9/13 but only 1/13 patients showed resolution. Rhythm of injection varied from one patient to another but 8/13 patients needing continuous injections had a constant time interval between injections. In 8/44 patients, laser photocoagulation had to be performed due to ischemic complications. The visual outcome using bevacizumab intravitreal injection was exceptionally good and functional parameters such as BCVA, MP, and VFT improved significantly. In about two-thirds of patients, resolution was obtained after 1-4 injections. In one-third of patients, continuous injections were necessary but a constant rhythm for re-injection for each patient could be established allowing to reduce to a minimum follow-up visits. The absence of significant side effects allowed to re-treat apparently without limitation achieving maintained visual function. FA monitoring for the detection of ischemic complications should not be neglected especially in cases where bevacizumab could be discontinued.

Bevacizumab compared with macular laser grid photocoagulation for cystoid macular edema in branch retinal vein occlusion

INTRODUCTION

To evaluate the outcome of cystoid macular edema treated with intravitreal injections of bevacizumab and macular grid laser photocoagulation (GLP), in patients with perfused branch retinal vein occlusion.

METHODS

Thirty eyes of 30 consecutive patients with cystoid macular edema secondary to nonischemic branch retinal vein occlusion were assigned to either GLP group or to intravitreal bevacizumab (IB) group. Complete ophthalmologic examinations were performed just before GLP and IB injection at 1, 3, 6, and 12 months after treatment. Changes in logarithm of minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA), central macular thickness (CMT) shown by optical coherence tomography-3 were evaluated.

RESULTS

Baseline BCVA (logMAR) and CMT were, respectively, 0.89 +/- 0.13 and 650 +/- 140 microm for the GLP group, 0.87 +/- 0.16 and 690 +/- 120 microm for the IB group. After the treatment, at 1, 3, 6, and 12 months in the GLP group, BCVA had improved by 0.19, 0.22, 0.21, and 0.20 logMAR, CMT had decreased by 40%, 41.3%, 40.5%, and 42%. In the IB group, BCVA had improved by 0.31, 0.32, 0.30, and 0.31 logMAR and CMT had decreased by 59.5%, 59%, 60%, and 60.3%. The group receiving bevacizumab had better BCVA and lower CMT values at all time points (P < 0.05).

CONCLUSION

Intravitreal bevacizumab injection improves BCVA and reduces CMT more than GLP. Intravitreal bevacizumab injection was well tolerated and could be used as primary treatment in patients with cystoid macular edema secondary to perfused branch retinal vein occlusion.

Ocular vascular thrombotic events: a diagnostic window to familial thrombophilia (compound factor V Leiden and prothrombin gene heterozygosity) and thrombosis

In a 12-member, 3-generation kindred with conjoint inheritance of G1691A factor V Leiden (FVL) and G20210A prothrombin gene (PTG) mutations, identified through a proband with amaurosis fugax and his father with nonarteritic ischemic optic neuropathy (NAION), the authors' hypothesis was that ocular thrombosis was a diagnostic window to familial thrombophilia-thrombosis. The authors used polymerase chain reaction (PCR) measures for thrombophilia (FVL, PTG, C677T-A1298C methylenetetrahydrofolate reductase [MTHFR], platelet glycoprotein PLA1A2) and hypofibrinolysis (plasminogen activator inhibitor-1 4G4G). The 39-year-old white male proband, with amaurosis fugax and transient ischemic attacks (TIA), was found to be a compound heterozygote for FVL and PTG mutations. His symptoms resolved only after coumadin. His 44-year-old brother (deep venous thrombosis [DVT]) and 46-year-old sister (DVT, pulmonary embolus [PE]) were compound FVL-PTG gene heterozygotes. Of 4 asymptomatic children born to these 3 siblings, 2 were FVL heterozygotes and 2 PTG heterozygotes. The proband's 69-year-old father, with NAION and ischemic stroke, had PTG heterozygosity, familial high factor VIII, and compound MTHFR C677T-A1298C mutation with homocysteinemia. The proband's 61-year-old aunt had PTG heterozygosity, recurrent DVT, and mesenteric artery thrombosis. The proband's 67-year-old mother, free of thrombotic events, was a FVL heterozygote, had high factor VIII, and PAI-1 4G4G homozygosity. In this extended kindred, ocular thrombotic events (amaurosis fugax, NAION) were associated with variegated thrombotic events, including TIA, ischemic stroke, DVT, PE, and mesenteric artery thrombosis, and opened a diagnostic window to family screening and treatment for complex thrombophilias, which had previously been undiagnosed.

Ocular vascular thrombotic events: central retinal vein and central retinal artery occlusions

We prospectively assessed associations of thrombophilia- hypofibrinolysis with central retinal vein occlusion (CRVO) (40 patients) and central retinal artery occlusion (CRAO) (9 patients). We used polymerase chain reaction measures for thrombophilia (factor V Leiden, prothrombin, C677T MTHFR, platelet glycoprotein PlA1/A2) and hypofibrinolysis (plasminogen activator inhibitor-1 4G4G). Serologic thrombophilia measures included protein C, protein S (total and free) and antithrombin III, homocysteine, lupus anticoagulant, anticardiolipin antibodies IgG-IgM, and factors VIII and XI. Serologic hypofibrinolysis measures included Lp(a) and plasminogen activator inhibitor activity. For comparison with 40 CRVO and 9 CRAO patients, 80 and 45 race-gender matched controls were studied. The factor V mutation was more common in CRVO (3/40, 8%) than controls (0/79, 0%), P = .036, as was high (>150%) factor VIII (12/40, 30%) versus (4/77, 5%), P = .0002. Low antithrombin III (<80%) was more common in CRVO (5/39, 13%) than in controls (2/73, 3%), P = .049. Homocysteine was high (> or =13.5 micromol/L) in 5/39 (13%) CRVO patients versus 2/78 controls (3%), P = .04. Three of 9 CRAO patients (33%) had low (<73%) protein C versus 2/37 controls (5%), P = .044. Two of 9 CRAO patients (22%) had high (> or =13.5 micromol/L) homocysteine versus 0/42 controls (0%), P =. 028. Four of 9 CRAO patients had the lupus anticoagulant (44%) versus 4/33 (12%) controls (P = .050). CRVO is associated with familial thrombophilia (factor V Leiden, factor VIII, low antithrombin III, homocysteinemia), and CRAO is associated with familial and acquired thrombophilia (low protein C, homocysteinemia, lupus anticoagulant), providing avenues for thromboprophylaxis, and triggering family screening.

Interventions for branch retinal vein occlusion: an evidence-based systematic review

TOPIC

To assess the evidence on interventions to improve visual acuity (VA) and to treat macular edema and/or neovascularization secondary to branch retinal vein occlusion (BRVO).

CLINICAL RELEVANCE

Branch retinal vein occlusion is the second most common retinal vascular disease.

METHODS/LITERATURE REVIEWED

English and non-English articles were retrieved using a keyword search of Medline (1966 onwards), Embase, the Cochrane Collaboration, the National Institute of Health Clinical Trials Database, and the Association for Research in Vision and Ophthalmology Annual Meeting Abstract Database (2003-2005). This was supplemented by hand searching references of review articles. Two investigators independently identified all randomized clinical trials (RCTs) with more than 3 months' follow-up.

RESULTS

From 4332 citations retrieved, 12 RCTs were identified. There were 5 RCTs on laser photocoagulation. Grid macular laser photocoagulation was effective in improving VA in 1 large multicenter RCT, the Branch Vein Occlusion Study (BVOS), but 2 smaller RCTs found no significant difference. The BVOS showed that scatter retinal laser photocoagulation was effective in preventing neovascularization and vitreous hemorrhage in patients with neovascularization, but a subsequent RCT found no significant effect. Randomized clinical trials evaluating intravitreal steroids (n = 2), hemodilution (n = 3), ticlopidine (n = 1), and troxerutin (n = 1) showed limited or no benefit.

CONCLUSIONS

There is limited level I evidence for any interventions for BRVO. The BVOS showed that macular grid laser photocoagulation is an effective treatment for macular edema and improves vision in eyes with VA of 20/40 to 20/200, and that scatter laser photocoagulation can effectively treat neovascularization. The effectiveness of many new treatments is unsupported by current evidence.

Interventions for Central Retinal Vein Occlusion

TOPIC

To assess the evidence for the effectiveness of interventions to improve visual acuity (VA) and prevent or treat neovascularization secondary to central retinal vein occlusion (CRVO).

CLINICAL RELEVANCE

Central retinal vein occlusion is a common cause of visual morbidity and blindness. Many different interventions have been advocated, but the evidence justifying their use remains unclear.

METHODS/LITERATURE REVIEWED

English and non-English language articles were retrieved using a keyword search of Medline (1966 onwards), Embase, the Cochrane Collaboration, the National Institutes of Health Clinical Trials database, and the Association for Research in Vision and Ophthalmology (2003-2005). This was supplemented by manually searching references of review articles. Two investigators independently identified all randomized clinical trials (RCTs) on interventions in CRVO with more than 3 months' follow-up.

RESULTS

Of 4133 citations retrieved, 17 RCTs comparing intervention with a control group were identified. There were 4 RCTs on laser photocoagulation. Grid macular laser photocoagulation did not improve VA in CRVO with macular edema. Prophylactic panretinal photocoagulation did not prevent angle and iris neovascularization in ischemic CRVO, but resulted in regression of angle and iris neovascularization and reduced progression to neovascular glaucoma. There were 4 RCTs that reported improvement in VA with inpatient hemodilution, 2 RCTs with no significant improvement, and 1 RCT showing deterioration in VA after outpatient hemodilution. Randomized clinical trials evaluating ticlodipine, troxerutin, and streptokinase showed a limited or no benefit.

CONCLUSIONS

This review found limited level I evidence for any intervention to improve VA in patients with CRVO. Panretinal photocoagulation resulted in regression of neovascularization. Hemodilution may improve vision in some patients, but the data conflict. More robust randomized controlled trials evaluating current treatments for CRVO are needed. The results of ongoing RCTs on intravitreal triamcinolone, anti-vascular endothelial growth factor agents, and chorioretinal anastomosis are awaited with interest.

Training room management of eye conditions

The number of preventable sports eye injuries resulting in permanent vision loss remains unacceptably high. Convincing athletes to use protective eyewear for sports is challenging, but worth the effort. Regardless, injuries still occur, and they must be diagnosed and treated promptly. Maintaining the skills necessary to perform a good fundoscopic examination will help to methodically work through the differential diagnoses. Cultivating a working relationship with an ophthalmologist and feeling comfortable consulting with him is always beneficial when an obvious cause of vision loss is not apparent. Although the majority of ophthalmologic issues in athletes can be managed well in the training room setting, always maintain a high level of vigilance for rarer and more serious ophthalmologic pathologies.