Selective intra-arterial fibrinolysis of acute central retinal artery occlusion

Interventions for acute non-arteritic central retinal artery occlusion

BACKGROUND

Acute central retinal artery occlusion occurs as a sudden interruption of the blood supply to the retina and results in an almost complete loss of vision in the affected eye. There is no generally agreed treatment regimen although a number of therapeutic interventions have been proposed.

OBJECTIVES

The objective of this review is to examine the effects of treatments used for acute non-arteritic central retinal artery occlusion.

SEARCH STRATEGY

We searched the Cochrane Controlled Trials Register - CENTRAL/CCTR, which contains the Cochrane Eyes and Vision Group specialised register (Cochrane Library Issue 4, 2001), MEDLINE (1966 to August 2001) and EMBASE (1980 to September 2001). We searched the reference lists of relevant papers for trials.

SELECTION CRITERIA

We included only randomised controlled trials in which one treatment aimed to re-establish blood supply to the retina in people with acute central retinal artery occlusion was compared to another treatment.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the search results for trials to be included in the review. Discrepancies were resolved by discussion.

MAIN RESULTS

We found no randomised controlled trials that met our inclusion criteria.

REVIEWER'S CONCLUSIONS

There is currently not enough evidence to decide which, if any, interventions for acute non-arteritic central retinal artery occlusion would result in any beneficial or harmful effect. Well-designed randomised controlled trials are needed to establish the most effective treatment.

Medical therapy for acute ischemic stroke

Over the past decade, there has been an explosion in data related to the treatment of patients with acute ischemic stroke. Thrombolytic therapy with intravenous tissue plasminogen activator has revolutionized the approach to stroke treatment. Intra-arterial administration of thrombolytic agents is also being investigated and is now being used on a compassionate basis. Medical management can have a large impact on stroke-related outcomes, even in patients who do not receive thrombolytic therapy.

Recent advances in the diagnosis and treatment of stroke

Stroke is defined as an abnormality in brain function resulting from disruption of cerebral circulation. It is the third leading cause of death in the United States and the primary cause of long-term disability. The economic burden of stroke will only increase as the population ages, making prevention and treatment of stroke one of the most important public health issues of the upcoming millennium. New therapies for the treatment of acute stroke, especially thrombolysis, have turned what was once considered an inevitable deficit into a potentially treatable illness. It is increasingly important for all physicians to be able to identify symptoms of cerebral ischemia. Neurons have a very limited tolerance for ischemia, making the rapid evaluation and diagnosis of stroke critical. This is particularly relevant for the ophthalmologist, who may be the first physician to see individuals presenting with visual deficits. Trials are underway to look specifically at central retinal artery and basilar artery ischemia and their response to thrombolytic therapy. This review will focus on description of recent advances in treatment and diagnosis of stroke, including thrombolytic trials and the expanding role of neuroimaging.

Update on ischemic stroke

Stroke is the second most common cause of death worldwide, exceeded only by heart disease. Epidemiologic studies have greatly enhanced our understanding of the factors that increase stroke risk. There have also been many recent developments in the understanding of the various etiologies of stroke as well as specific new treatments. The characteristic sudden onset and rapid tissue damage make stroke particularly challenging to treat. The most promising therapy for acute ischemic stroke is the use of a thrombolytic agent. This has been the focus of recent large trials and remains a challenging treatment for cerebral ischemic stroke as well as for retinal artery occlusion. Because neuro-ophthalmic symptoms and signs such as vision loss and diplopia are common in patients with stroke, patients are often seen by ophthalmologists prior to their primary care physicians or neurologists. The ophthalmologist should be aware of some of the new diagnostic and therapeutic issues in the management of patients with acute ischemic stroke. This review emphasizes some of the controversial topics published during the past few years.

Local intra-arterial fibrinolysis for acute occlusion of the central retinal artery: a meta-analysis of the published data

BACKGROUND/AIM

Central retinal artery occlusion (CRAO) is typically associated with a poor visual outcome. Several favourable reports of local intra-arterial fibrinolysis (LIF), which involves the superselective administration of a thrombolytic agent directly into the ophthalmic artery, have appeared in the recent literature. The aim of this study was to critically appraise these studies in a collective fashion.

METHODS

A meta-analysis was performed of all the published literature germane to LIF in cases of CRAO.

RESULTS

Of the 16 studies identified, all were retrospective and non-randomised. After correction for data duplication, the results of LIF in 100 patients can be reported. A final acuity of 6/6 or better was seen in 14% of patients following LIF, and a visual result of 6/12 or better was seen in 27% of subjects. A poor final acuity of 3/60 or worse was seen in 60.6% of eyes treated with local intra-arterial fibrinolysis. These results compare favourably with conventional forms of therapy. Potentially serious complications were seen in four patients, but no patient suffered a permanent neurological deficit.

CONCLUSION

The results of this study suggest that there may be a marginal visual benefit associated with LIF compared with conventional management of CRAO. However, the methodology of the cited studies was often unsatisfactory, and a randomised controlled trial of LIF in cases of CRAO is justified. Outside of a randomised clinical trial, the use of superselective fibrinolytic therapy for CRAO cannot be recommended on the basis of current evidence.

Optic disk and retinal nerve fiber layer damage after transient central retinal artery occlusion: an experimental study in rhesus monkeys

PURPOSE

To evaluate the retinal tolerance time to acute ischemic insult in middle-aged or elderly rhesus monkeys with pre-existing atherosclerosis and arterial hypertension.

METHODS

In 39 eyes of 39 middle-aged and elderly rhesus monkeys with a mean age of 19.5 +/- 2. 8 years, occlusion of the central retinal artery was produced by temporary clamping of the central retinal artery at its site of entry into the dural sheath of the optic nerve for 97 to 300 minutes. Stereoscopic color fundus photography and fluorescein fundus angiography were performed before central retinal artery occlusion and serially thereafter. Retinal nerve fiber layer damage and optic disk changes were assessed by comparing morphometric evaluation of the color fundus photographs taken before central retinal artery occlusion and color fundus photographs taken at the end of the study.

RESULTS

There was a significant correlation between duration of central retinal artery occlusion and decreased visibility of retinal nerve fiber layer (P =.018) and increasing optic disk pallor (P =. 014), and a trend between residual retinal circulation and decreased visibility of retinal nerve fiber layer (P =.085) and optic disk pallor (P =.162). However, there was a marked interindividual variation between the length of central retinal artery occlusion and degree of increased optic disk pallor and decreased visibility of the retinal nerve fiber layer, even among eyes with similar duration of central retinal artery occlusion. Complete or almost total optic nerve atrophy and nerve fiber damage were present in all eyes in which the duration of central retinal artery occlusion was 240 minutes or more.

CONCLUSIONS

The findings of this study, compared with our previous study in young healthy rhesus monkeys, indicate that in middle-aged or elderly atherosclerotic and arterial hypertensive rhesus monkeys, central retinal artery occlusion for less than 100 minutes produced no apparent morphometric evidence of optic nerve damage; however, central retinal artery occlusion of 105 minutes but less than 240 minutes produced a variable degree of damage; central retinal artery occlusion for 240 minutes or more produced total or almost total optic nerve atrophy and nerve fiber damage.

Intra-arterial thrombolysis in acute stroke

A relatively small number of studies were published on the intra-arterial therapy of stroke in the past year. Those reports, however, do offer strong evidence for the feasibility and safety of this therapeutic approach. Partly on the basis of these data it has become evident that the intra-arterial thrombolytic therapy of acute ischemic stroke is at least as effective as intravenous thrombolysis. There remain, however, many unresolved issues before such therapy can become a part of the standard of care.