Treatment of Central Retinal Vein Occlusion-Related Macular Edema with Intravitreal Bevacizumab (Avastin®): Preliminary Results

[Management of macular edema secondary to retinal vein occlusion]

BACKGROUND

In recent years, intravitreal injections have added to the treatment modalities available for macular edema (ME) secondary to retinal vein occlusion (RVO). This article aims to provide an update regarding the management of ME secondary to RVO.

METHODS

A work group met in order to analyze the literature available on Embase/PubMed, regarding treatments for venous occlusion that have received market approval and are reimbursed in France. In total, 33 articles were selected. Consensus within the group for recommendations was based on this data from the literature review and clinical experience and was reported in this article.

RESULTS

The management of ME secondary to branch retinal vein occlusion (BRVO) or central vein occlusion of the retina (CRVO) differs on a number of points. Methods of best practice were discussed separately for BRVO and CRVO, taking into account various ocular and associated parameters.

DISCUSSION

Ranibizumab and dexamethasone implant are the first-line treatments for visual impairment due to ME secondary to RVO. The choice of either of these drugs may take into account various ocular and extraocular parameters. A change of treatment to one or the other or to laser may also be considered during follow-up.

Steroids and macular edema from retinal vein occlusion

PURPOSE

The possibility of applying long-lasting steroids, such as triamcinolone and subsequently dexamethasone implant, directly in the eye, without the systemic side effects observed after their oral or intravenous administration, aroused great enthusiasm among ophthalmologists.

METHODS AND RESULTS

The SCORE study, a multicenter clinical trial, compared the efficacy and safety of 1-mg and 4-mg doses of preservative-free intravitreal triamcinolone with observation in central retinal vein occlusion (CRVO) participants with macular edema secondary to perfused CRVO. This study marked a turning point in the management of retinal vein occlusion (RVO), since it was the first report on an effective treatment of macular edema due to CRVO. But in branch retinal vein occlusion (BRVO), the SCORE study showed no difference in visual acuity for the standard care group compared with the triamcinolone groups; however, the rates of adverse events (particularly elevated intraocular pressure and cataract) were highest in the 4-mg group. The authors concluded that laser grid photocoagulation should remain the benchmark against which other treatments should be compared. The Geneva Study, a randomized, controlled, clinical trial, conducted to evaluate the safety and efficacy of an intravitreal implant that delivers sustained levels of dexamethasone (Ozurdex™), studied the largest group of RVO patients with macular edema (1267 patients), including 35% CRVO and 65% BRVO. The study demonstrated that this slow-release device could both reduce the risk of vision loss and improve the speed and incidence of visual improvement in eyes with macular edema secondary to CRVO and BRVO, with fewer side effects, such as elevation of intraocular pressure or cataract. Other ongoing studies evaluate the safety and efficacy of anti-vascular endothelial growth factor injection; preliminary results showed that these therapies are effective in decreasing macular edema and improving visual acuity, with fewer ocular adverse effects, but their duration of action seems limited.

CONCLUSIONS

These recent studies result in a great change in the management of macular edema from RVO. Unfortunately, long-term studies on safety and efficacy are not yet available, and further studies will have to show whether the short-term benefits are only transient or may finally lead to a long-lasting improvement in vision.

Prospective study of peripheral panretinal photocoagulation of areas of nonperfusion in central retinal vein occlusion

PURPOSE

To investigate the effect that panretinal photocoagulation to peripheral areas of retinal vascular nonperfusion has on the visual acuity and injection frequency of ranibizumab in eyes with previous central retinal vein occlusion.

METHODS

Patients enrolled in a prospective study of ranibizumab for central retinal vein occlusion were imaged with wide-field angiography using the Optos P200 system. Laser photocoagulation was carried out and the extent of laser photocoagulation was evaluated with repeat wide-field angiography. Injection of ranibizumab was based on an as needed strategy throughout the study. The injection frequency in the 6 months before laser was compared with a 6-month period starting 2 months after the laser photocoagulation. The visual acuity was measured by Early Treatment Diabetic Retinopathy Study protocol refraction at both the end of the 6-month follow-up period and at the time of laser photocoagulation.

RESULTS

There were 10 patients treated in this study with a mean number of 1,757 spots of laser photocoagulation in the peripheral retina. The injection frequency in the 6-month lead-in period was 3.4 and in the 6-month follow-up period was 3.1, a difference that was not significant (P = 0.26). The visual acuity at the time of laser photocoagulation was 54.2 letters (approximate Snellen equivalent of 20/80) and at the end of the observation period was 51.4 letters, a difference that was not significant (P = 0.33).

CONCLUSION

In this small study, laser photocoagulation to peripheral areas of nonperfusion as visualized by wide-field angiography did not result in either decreased injection frequency or improved visual acuity in eyes with central retinal vein occlusion treated with ranibizumab.

Anti-vascular endothelial growth factor for macular edema secondary to central retinal vein occlusion

BACKGROUND

Central retinal vein occlusion (CRVO) is a common retinal vascular disorder in which macular edema (ME) may develop, with a consequent reduction in visual acuity. The visual prognosis in CRVO-ME is poor in a substantial proportion of patients, especially those with the ischemic subtype, and until recently there has been no treatment of proven benefit. Macular grid laser treatment is ineffective, and whilst a few recent randomized controlled trials (RCTs) suggest short-term gains in visual acuity with intravitreal steroids for patients with non-ischemic CRVO-ME, there is no established treatment for ischemic CRVO-ME. Anti-vascular endothelial growth factor (anti-VEGF) agents have been used to treat ME resulting from a variety of causes and may represent a treatment option for CRVO-ME.

OBJECTIVES

To investigate the effectiveness and safety of intravitreal anti-VEGF agents in the treatment of CRVO-ME.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2010, Issue 8), MEDLINE (January 1950 to August 2010), EMBASE (January 1980 to August 2010), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to August 2010), Cumulative Index to Nursing and Allied Health Literature (CINAHL) (January 1937 to August 2010), OpenSIGLE (January 1950 to August 2010), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov). There were no language or date restrictions in the search for trials. The electronic databases were last searched on 10 August 2010.

SELECTION CRITERIA

We considered RCTs that compared intravitreal anti-VEGF agents of any dose or duration to sham injection or no treatment. We focused on studies that included individuals of any age or gender with unilateral or bilateral disease and a minimum of six months follow up. Secondarily, we considered non-randomized studies with the same criteria, but did not conduct a separate electronic search for these.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

We found two RCTs that met the inclusion criteria after independent and duplicate review of the search results. These RCTs utilized different anti-VEGF agents which cannot be assumed to be directly comparable. We, therefore, performed no meta-analysis. Evidence from these trials and from other non-randomized case series is summarized in this review.

AUTHORS' CONCLUSIONS

Ranibizumab and pegaptanib sodium have shown promise in the short-term treatment of non-ischemic CRVO-ME. However, effectiveness and safety data from larger RCTs with follow up beyond six months are not yet available. There are no RCT data on anti-VEGF agents in ischemic CRVO-ME. The use of anti-VEGF agents to treat this condition therefore remains experimental.

[Isovolumic hemodilution in the management of the acute phase of central retinal vein occlusion: a pilot study]

INTRODUCTION

Cases series and randomized studies support the use of isovolumic hemodilution at the acute phase of the central retinal vein occlusion (CRVO). However, a recent meta-analysis showed the difficulty of interpreting the long-term effect of isovolumic hemodilution because of the late complications and the concomitant use of other treatments. We present here a pilot case-series study aiming to demonstrate the effect of isovolumic hemodilution at the acute phase of the disease, before any other treatment was applied.

PATIENTS AND METHOD

Twenty-two consecutive cases of CRVO were prospectively treated with isovolumic hemodilution within 15 days of disease onset (substitution of 10 ml/kg of blood by a macromolecular solution (Voluven), aiming at a hematocrit of 35%). The treatment was performed in ambulatory conditions after excluding common contraindications (cardiac, respiratory and renal insufficiency, angina pectoris, history of heart attack or stroke during the last 6 months). The patients were followed prospectively with respect to visual acuity, fluorescein angiography and visual acuity at one week, one month, three months and twelve months.

RESULTS

Visual acuity improved of at least one ETDRS line (5 letters) in 59% of the patients one week after the treatment. Improvement in the haemodynamic was observed in all these cases on fluorescein angiography. The vision remained stable at 1 month and 3 months before any other treatment was applied. After the 3rd month, additional intravitreous injection of triamcinolone was applied in 32% of eyes for persistent macular edema. At 12 months after hemodilution, visual acuity improved in 64% of cases and only 5% of the eyes converted into an ischemic CRVO.

DISCUSSION

Isovolumic hemodilution at the acute phase of the CRVO is followed by an improvement in both vision and angiographic characteristics in more than 60% of our patients and the conversion into an ischemic form was limited to 5% of eyes. Further randomized studies are needed to evaluate the specific effect of hemodilution in the long term.

Hemorrhagic Macular Infarction After Intravitreal Bevacizumab for Central Retinal Vein Occlusion

Intravitreal bevacizumab for macular edema secondary to central retinal vein occlusion may induce resolution of macular edema. However, the possibility of a rebound macular edema thicker than at the initial presentation after intravitreal bevacizumab injections has been reported. A case of dramatic deterioration of central retinal vein condition with hemorrhagic macular infarction 3 weeks after intravitreal injection of bevacizumab is presented.

[Retinal vein occlusion: anti-VEGF treatments]

To date, there is no consistently effective proven therapy for patients with macular edema resulting from central retinal vein occlusion. Grid laser treatment only showed visual acuity benefit in branch retinal vein occlusion. Other treatment like intravitreal triamcinolone acetonide demonstrated transient inconsistent benefit with potential complications. As retinal vein occlusion is associated with increased levels of Vascular Endothelial Growth Factor (VEGF), anti-VEGF therapy was proposed to be a promising strategy for retinal vein occlusion. We reviewed the current literature on this topic: case reports, non controlled and non randomized trials. Short term results are encouraging with visual acuity benefit associated with reduction of retinal central thickness but multiple injections seems to be necessary to achieve visual stabilization. Further randomized and controlled clinical trials are necessary to confirm the long term safety and efficacy of bevacizumab in the care of retinal vein occlusion edema treatment.