Thrombolytic therapy in central retinal artery occlusion: cutting edge therapy, standard of care therapy, or impractical therapy?

Difference in topographic morphology of optic nerve head and neuroretinal rim between normal tension glaucoma and central retinal artery occlusion

Although central retinal artery occlusion (CRAO) has its own defining pathomechanism and clinical characteristics, morphologic feature of the optic nerve head (ONH) during its later stage is not diagnostic, which makes it difficult to differentiate CRAO from other optic neuropathies. This cross-sectional study was performed to investigate the differences in the topographic morphology of the ONH in eyes with normal-tension glaucoma (NTG) and CRAO. Thirty-one eyes with NTG; 31 eyes with CRAO; and 31 healthy fellow eyes of the subjects with CRAO were included. ONH morphology was evaluated by measuring horizontal rim width (HRW), minimal rim width in the selected horizontal image (MRW), and lamina cribrosa curvature index (LCCI) in horizontal B-scan images obtained using enhanced depth-imaging optical coherence tomography. HRW was smaller and LCCI was larger in NTG eyes than in both CRAO and healthy fellow eyes (both P < 0.001), while both were comparable between CRAO and healthy fellow eyes. MRW differed significantly among the three groups, being smallest in NTG eyes followed by CRAO and healthy fellow eyes (P < 0.001). NTG and CRAO eyes with a similar degree of RNFL loss differed in ONH morphology, indicating that mechanisms of ONH damage differ between these two conditions.

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.

Central retinal artery occlusion - rethinking retinal survival time

Background

The critical time from onset of complete occlusion of the central retinal artery (CRA) to functionally significant inner retinal infarction represents a window of opportunity for treatment and also has medical-legal implications, particularly when central retinal artery occlusion (CRAO) complicates therapeutic interventions. Here, we review the evidence for time to infarction from complete CRAO and discuss the implications of our findings.

Methods

A Medline search was performed using each of the terms “central retinal artery occlusion”, “retinal infarction”, “retinal ischemia”, and “cherry red spot” from 1970 to the present including articles in French and German. All retrieved references as well as their reference lists were screened for relevance. An Internet search using these terms was also performed to look for additional references.

Results

We find that the experimental evidence showing that inner retinal infarction occurs after 90–240 min of total CRAO, which is the interval generally accepted in the medical literature and practice guidelines, is flawed in important ways. Moreover, the retinal ganglion cells, supplied by the CRA, are part of the central nervous system which undergoes infarction after non-perfusion of 12–15 min or less.

Conclusions

Retinal infarction is most likely to occur after only 12–15 min of complete CRAO. This helps to explain why therapeutic maneuvers for CRAO are often ineffective. Nevertheless, many CRAOs are incomplete and may benefit from therapy after longer intervals. To try to avoid retinal infarcton from inadvertent ocular compression by a headrest during prone anesthesia, the eyes should be checked at intervals of less than 15′.

Observation on therapeutic efficacy of rt-PA intravenous thrombolysis combined with compound anisodine injection on central retinal artery occlusion

The aim of the present study was to observe the clinical efficacy and safety of recombinant tissue plasminogen activator (rt-PA) combined with compound anisodine in treating central retinal artery occlusion (CRAO). Forty-eight patients diagnosed with CRAO were randomly divided into a treatment group (24 cases) and a control group (24 cases). For the control group, nitroglycerin, 654-2, methazolamide, puerarin and compound anisodine were used for the treatment, along with oxygen, massage and other conventional treatments. Besides conventional therapy, the treatment group was also given intravenous rt-PA thrombolysis. Visual acuity, fundus oculi, visual field changes were taken as indicators for efficacy evaluation. It was found that the total effective rate of the control group was 70.83%, while that for the treatment group was 91.67%, and the comparative difference between the two groups was of statistical significance (p<0.05). The visual field defect of the control group after treatment was approximately 74.26±12.91%, and the visual field defect of the treatment group after treatment approximately 35.08±16.33%; thus, the comparative difference was statistically significant (p<0.01). The comparative difference of the original contents of fibrous protein in blood in the treatment group before and after treatment was statistically significant (p<0.01). In conclusion, the result show that intravenous thrombolysis with rt-PA combined with compound anisodine is safe and effective in treating CRAO, which can significantly improve the prognosis of patients.

Iatrogenic Central Retinal Artery Occlusion Following Retrobulbar Anesthesia for Intraocular Surgery

Purpose

To present clinical features of central retinal artery occlusion (CRAO) following retrobulbar anesthesia for intraocular surgery.

Methods

This observational case series describes 5 consecutive patients with acute CRAO following retrobulbar anesthesia for intraocular surgery. Data collected for this study included subject characteristics, retrobulbar anesthesia technique, treatment type, initial and final best-corrected visual acuity, and other ophthalmologic examinations.

Results

Mean subject age was 67.0 ± 8.2 years (range, 53 to 72 years). All patients had one or more vascular risk factors (e.g., hypertension, cerebral infarction, carotid artery stenosis) and presented with acute vision loss 1 day after uneventful intraocular surgery (cataract surgery in 2 eyes and vitrectomy in 3 eyes). All 5 patients received retrobulbar anesthesia during surgery, 4 of which involved the use of a sharp needle. No immediate complications were noted during intraocular surgery. Final visual prognosis was poor (from finger count to no light perception) although intraocular thrombolysis was attempted in 3 patients.

Conclusions

Iatrogenic CRAO is a potential complication of retrobulbar anesthesia for intraocular surgery in elderly patients with vascular risk factors. Unfortunately, this complication can lead to severe vision loss. We conclude that retrobulbar anesthesia for intraocular surgery should be performed with great care and special consideration for elderly patients with vascular risk factors.

Low endogenous recanalization in embolic central retinal artery occlusion--the retrobulbar "spot sign"

BACKGROUND AND PURPOSE

Central retinal artery occlusion (CRAO) is most often indirectly diagnosed by lack of retinal perfusion. Direct embolus characterization may help to understand the natural course and low response to treatment. In a previous study we identified a hyperechoic signal within the optic nerve and in the central retinal artery ("spot sign").

METHODS

In this study we performed a follow-up investigation in 7 patients with CRAO and positive spot sign indicating the embolic cause of the occlusion after a median interval of 17 months (range 11-38 months) using a battery of tests (ocular color-coded sonography, optic coherence tomography [OCT], fundoscopy, amongst others).

RESULTS

The spot sign persisted in all patients, none had high-grade internal carotid artery stenosis, stroke or transient ischemic attacks. Four patients were completely blind, 3 patients were able to recognize hand movements. OCT demonstrated retinal atrophy, and fundoscopy revealed only minimal arterial perfusion.

CONCLUSIONS

The hyperechoic spot sign may be an important predictive prognostic marker for persistent loss of vision. Its persistence may indicate calcified or cholesterol emboli and may explain the low therapeutic success rate to thrombolysis. Further studies on their origin and significance in atherosclerotic disease are warranted.

Region-specific expression of vesicular glutamate and GABA transporters under various ischaemic conditions in mouse forebrain and retina

There is accumulating evidence that glutamate and GABA release are key mechanisms of ischaemic events in the CNS. However, data on the expression of involved transporters for these mediators are inconsistent, potentially impeding further neuroprotective approaches. Here, we applied immunofluorescence labelling to characterise the expression pattern of vesicular glutamate (VGLUT) and GABA transporters (VGAT) after acute focal cerebral ischaemia and in two models of retinal ischaemia. Mice were subjected to filament-based focal cerebral ischaemia predominantly involving the middle cerebral artery territory, also leading to retinal ischaemia due to central retinal artery occlusion (CRAO). Alternatively, retinal ischaemia was induced by a transient increase of the intraocular pressure (HIOP). One day after ischaemia onset, diminished immunolabelling of neuronal nuclei and microtubule-associated protein 2-positive structures were found in the ipsilateral neocortex, subcortex and the retina, indicating neuronal degeneration. VGLUT1 expression did not change significantly in ischaemic tissues whereas VGLUT2 was down-regulated in specific areas of the brain. VGLUT3 expression was only slightly down-regulated in the ischaemia-affected neocortex, and was found to form clusters on fibrils of unknown origin in the ischaemic lateral hypothalamus. In contrast, retinae subjected to CRAO or HIOP displayed a rapid loss of VGLUT3-immunoreactivity. The expression of VGAT appears resistant to ischaemia as there was no significant alteration in all the regions analysed. In summary, these data indicate a region- and subtype-specific change of VGLUT expression in the ischaemia-affected CNS, whose consideration might help to generate specific neuroprotective strategies.

Ophthalmic features of systemic diseases

The eye is intricately integrated with the functions of the body. Ocular changes may precede or run concurrently with various systemic conditions and often represent important prognostic indicators of disease progression. In addition to a thorough diagnostic evaluation and treatment of underlying processes, individuals with systemic diseases and concurrent ocular changes may need comprehensive ophthalmic examination to reduce the risk of visual impairment and morbidity. In this review the authors highlight the clinically relevant ocular signs that occur parallel with systemic conditions. In particular, the study focuses on the varied clinical presentations that can lead to rapid diagnosis to improve management of eye disorders that accompany systemic diseases.

Treatments for neuro-ophthalmologic conditions

Neuro-ophthalmology covers disorders that fall between the cracks of Neurology and Ophthalmology. Neurologists see patients with neuro-ophthalmic disorders. Recognition of the diagnosis is difficult enough, but treatment can be challenging. This article reviews several common neuro-ophthalmic disorders, outlining their features and treatments, from retinal vascular disorders to eye movements and blepharospasm.