Study of the Efficacy of Intravenous Tissue Plasminogen Activator in Central Retinal Artery Occlusion

Central retinal artery occlusion: a stroke of the eye

Central retinal artery occlusion (CRAO), like a stroke in the brain, is a critical eye condition that requiring urgent medical attention. Patients with CRAO present with acute loss of vision and the visual prognosis is poor with low chance of spontaneous visual recovery. Moreover, the risk of developing ischaemic heart disease and cerebral stroke is increased due to the presence of underlying atherosclerotic risk factors. Currently, there is no officially recommended treatment for CRAO. This review will describe the anatomy, pathophysiology, clinical features of CRAO, as well as exploring existing and potential future approaches for managing the condition.

Interventions for acute non-arteritic central retinal artery occlusion

BACKGROUND

Acute non-arteritic central retinal artery occlusion (CRAO) occurs as a sudden interruption of the blood supply to the retina and typically results in severe loss of vision in the affected eye. Although many therapeutic interventions have been proposed, there is no generally agreed upon treatment regimen.

OBJECTIVES

To assess the effects of treatments for acute non-arteritic CRAO.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2022, Issue 2); Ovid MEDLINE; Embase.com; PubMed; Latin American and Caribbean Health Sciences Literature Database (LILACS); ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 15 February 2022.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing any interventions with another treatment in participants with acute non-arteritic CRAO in one or both eyes.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodology and graded the certainty of the body of evidence for primary (mean change in best-corrected visual acuity [BCVA]) and secondary (quality of life and adverse events) outcomes using the GRADE classification.

MAIN RESULTS

We included six RCTs with 223 total participants with acute non-arteritic CRAO; the studies ranged in size from 10 to 84 participants. The included studies varied geographically: one in Australia, one in Austria and Germany, two in China, one in Germany, and one in Italy. We were unable to conduct any meta-analyses due to study heterogeneity. None of the included studies compared the same pair of interventions: 1) tissue plasminogen activator (t-PA) versus intravenous saline; 2) t-PA versus isovolemic hemodilution, eyeball massage, intraocular pressure reduction, and anticoagulation; 3) nitroglycerin, methazolamide, mecobalamin tablets, vitamin B1 and B12 injections, puerarin and compound anisodine (also known as 654-2) along with oxygen inhalation, eyeball massage, tube expansion, and anticoagulation compared with and without intravenous recombinant tissue plasminogen activator (rt-PA); 4) transcorneal electrical stimulation (TES) with 0 mA versus with 66% of the participant's individual electrical phosphene threshold (EPT) at 20 Hz (66%) versus with 150% of the participant's individual EPT (150%) at 20 Hz; 5) ophthalmic artery branch retrograde thrombolysis versus superselective ophthalmic artery thrombolysis; and 6) pentoxifylline versus placebo. There was no evidence of an important difference in visual acuity between participants treated with t-PA versus intravenous saline (mean difference [MD] at 1 month -0.15 logMAR, 95% confidence interval [CI] -0.48 to 0.18; 1 study, 16 participants; low certainty evidence); t-PA versus isovolemic hemodilution, eyeball massage, intraocular pressure reduction, and anticoagulation (MD at 1 month -0.00 logMAR, 95% CI -0.24 to 0.23; 1 study, 82 participants; low certainty evidence); and TES with 0 mA versus TES with 66% of EPT at 20 Hz versus TES with 150% of EPT at 20 Hz. Participants treated with t-PA experienced higher rates of serious adverse effects. The other three comparisons did not report statistically significant differences. Other studies reported no data on secondary outcomes (quality of life or adverse events).  AUTHORS' CONCLUSIONS: The current research suggests that proposed interventions for acute non-arteritic CRAO may not be better than observation or treatments of any kind such as eyeball massage, oxygen inhalation, tube expansion, and anticoagulation, but the evidence is uncertain. Large, well-designed RCTs are necessary to determine the most effective treatment for acute non-arteritic CRAO.

Safety and effectiveness of a novel neuroprotectant, KUS121, in patients with non-arteritic central retinal artery occlusion: An open-label, non-randomized, first-in-humans, phase 1/2 trial

Kyoto University Substance (KUS) 121, an ATPase inhibitor of valosin-containing protein, is a novel neuroprotectant. We tested the safety and effectiveness of KUS121 in patients with acute central retinal artery occlusion (CRAO). We conducted an investigator-initiated, first-in-humans, phase 1/2 clinical trial. Nine patients with non-arteritic CRAO symptoms lasting for 4–48 h were enrolled. These patients received daily intravitreal injections of KUS121 for 3 days: 25 μg (low-dose) in the first three patients and 50 μg (high-dose) in the next six patients. The primary endpoint was the safety of the drug. As a secondary endpoint, pharmacokinetics was evaluated. Other key secondary endpoints were changes in best-corrected visual acuity (BCVA), measured using the Early Treatment Diabetic Retinopathy Study chart, visual field scores, and retinal sensitivities between baseline and week 12; and decimal BCVA at week 12. Administration of KUS121 did not result in serious adverse events. All nine patients (100%) showed significant improvement of BCVA. Average readable letter counts, visual field scores, and retinal sensitivities also improved. Decimal BCVA at week 12 was better than 0.1 in four patients (44%) and equal to or better than 0.05 in seven patients (78%). This first-in-humans clinical trial provides support for the safety and efficacy of intravitreal KUS121 injection. To substantiate the safety and effectiveness for patients with acute CRAO, further larger scale clinical studies will be needed.

Intra-Arterial Thrombolysis for Central Retinal Artery Occlusion

Introduction

Central retinal artery occlusion is an ophthalmic emergency which typically causes acute, painless visual loss. Several conservative treatment options are practiced with little benefit. Thrombolysis as a therapeutic option has gathered interest as well as controversy. This paper aims at reviewing the relevant literature to assess the efficacy and safety of intra-arterial thrombolysis for acute central retinal artery occlusion.

Methods

A review of the literature was conducted. Keywords included “intra-arterial thrombolysis” or “intra-arterial fibrinolysis” in combination with “central retinal artery occlusion” or “CRAO”. A Cochrane Database search was performed for randomised control trials, systematic reviews and meta-analyses using the same keywords.

Results

Twenty-eight studies were identified which included case reports, case series, case-control studies and 1 randomised control trial: the European Assessment Group for Lysis in the Eye Study. Improvement in vision was measured using different methods and at different time points. The findings of these studies generally favour an effect towards intra-arterial thrombolysis however there are many limitations. Additionally, the European Assessment Group for Lysis in the Eye Study showed lack of effect in intra-arterial thrombolysis vs conservative measures.

Conclusion

Current evidence is not sufficient to recommend intra-arterial thrombolysis due to the variability of visual improvement within retrospective studies, heterogeneity in treatment regimens between studies and adverse effects. Intra-arterial thrombolysis may have a role in patients presenting early, particularly if they have monocular vision, after discussion of the risks and benefits. Further high-quality trials assessing the clinical efficacy of intra-arterial thrombolysis may shed more light on this topic.

Plasminogen activators and ischemic stroke: conditions for acute delivery

Appropriate acute treatment with plasminogen activators (PAs) can significantly increase the probability of minimal or no disability in selected ischemic stroke patients. There is a great deal of evidence showing that intravenous recombinant tissue PAs (rt-PA) infusion accomplishes this goal, recanalization with other PAs has also been demonstrated in the development of this treatment. Recanalization of symptomatic, documented carotid or vertebrobasilar arterial territory occlusions have also been achieved by local intra-arterial PA delivery, although only a single prospective double-blinded randomized placebo-controlled study has been reported. The increase in intracerebral hemorrhage with these agents by either delivery approach underscores the need for careful patient selection, dose-appropriate safety and efficacy, proper clinical trial design, and an understanding of the evolution of cerebral tissue injury due to focal ischemia. Principles underlying the evolution of focal ischemia have been expanded by experience with acute PA intervention. Several questions remain open that concern the manner in which PAs can be applied acutely in ischemic stroke and how injury development can be limited.

Efficacy of intravenous tissue-type plasminogen activator in central retinal artery occlusion: report from a randomized, controlled trial

BACKGROUND AND PURPOSE

Central retinal artery occlusion is caused by a platelet-fibrin thrombus or embolic occlusion and is a stroke of the eye. Observational studies suggest that thrombolytics may restore ocular perfusion and visual function. We hypothesized that intravenous tissue-type plasminogen activator (tPA) administered within 24 hours of symptom onset might restore ocular perfusion and visual function.

METHODS

A placebo-controlled, randomized trial of intravenous tPA versus intravenous saline was performed in patients with clinically defined central retinal artery occlusion within 24 hours of symptom onset. tPA was administered at a total dose of 0.9 mg/kg, with 10% given as a 1-minute bolus and the remainder over 1 hour. An improvement of visual acuity of 3 lines or more was considered significant.

RESULTS

Twenty-five percent (2 of 8) of the tPA group experienced the primary outcome at 1 week after tPA versus none of the placebo group. One patient had an intracranial hemorrhage. The visual acuity improvement of these 2 patients was not sustained at 6 months. In both patients, tPA was administered within 6 hours of symptom onset.

CONCLUSIONS

Although essentially a negative study, it does add to the evidence base of reperfusion in central retinal artery occlusion by showing that the time window for intervention is likely to be <6 hours. Reocclusion is a potential problem and may require adjuvant anticoagulation. Future studies should concentrate on determining the efficacy of thrombolytics in the <6-hour time window. Clinical Trial Registration- URL: http://www.anzctr.org.au. Unique identifier: 83102.