Long-term follow-up of a modified technique for laser-induced chorioretinal venous anastomosis in nonischemic central retinal vein occlusion

Chorioretinal Anastomosis for Central Retinal Vein Occlusion: A Review of Its Development, Technique, Complications, and Role in Management

Treatments for central retinal vein occlusion (CRVO) have improved dramatically with the advent of intravitreal agents aimed at blocking the effects of the dominant hypoxia-induced upreglulated cytokine, which is vascular endothelial growth factor (VEGF). This cytokine breaks down the capillary endothelial barriers and is a major component of the macular edema in this condition. These treatments although impressive only address some of the sequelae of CRVO and have no effect on the underlying cause which is an obstruction to venous outflow leading to retinal blood flow stagnation and an elevation of the retinal central venous pressure (CVP). The creation of a laser-induced chorioretinal anastomosis (L-CRA) between the obstructed high pressure retinal venous circulation and the unobstructed low pressure choroidal venous circulation is a means addressing the causal pathology. The L-CRA will help lower the elevated CVP, which has been up until now an unaddressed component of the macular edema in this condition.This article reviews the preclinical and clinical development of the L-CRA and the results of the studies into its effect on the natural history of CRVO. It now can be used in combination with existing anti-VEGF treatments with the intravitreal agents addressing the component of the CRVO-induced macular edema due to the cytokine dysregulation, and the L-CRA addressing the component due to the elevated CVP and retinal venous stagnation. Improvements in laser technology have led to higher success rates in L-CRA creation and potential complications are now minimized and better controlled. The combination of L-CRA with intravitreal anti-VEGF agents offers the potential of a permanent cure with a significant reduction in the burden of therapy and improved visual outcomes in this condition.

Vitreous hemorrhage and fibrovascular proliferation after laser-induced chorioretinal venous anastomosis

AIM

To describe a case in which vitrectomy was required for vitreous hemorrhage and fibrovascular proliferation after laser-induced chorioretinal venous anastomosis (LCVA) for non-ischemic central retinal vein occlusion (CRVO).

METHODS

Observational case report.

RESULTS

A 72-year-old man complained of central scotoma in the left eye, and was diagnosed as suffering from non-ischemic CRVO. LCVA was performed in another hospital. Although favorable visual function was briefly maintained postoperatively,severe vitreous hemorrhage developed in his left eye, necessitating vitrectomy.

CONCLUSION

Considering that LCVA carries a risk of serious complications, we must apply this treatment with caution, especially in ethnic groups, such as the Japanese, in whom pigmentation reacts to photocoagulation excessively.

Retinal vein occlusion: an approach to diagnosis, systemic risk factors and management

Retinal vein occlusion (RVO) is the second most common retinal vascular disease after diabetic retinopathy and is a common cause of visual morbidity and blindness in the elderly. A large proportion of patients with RVO have a history of cardiovascular disease, hypertension, diabetes mellitus or open-angle glaucoma. Although RVO is sometimes associated with thrombophilias and coagulation abnormalities, the role of coagulation factors in the development of RVO remains unclear. This review did not find strong evidence to support an extensive work-up for thrombophilic and coagulation diseases for the vast majority of patients. However, when tests for common cardiovascular risk factors for RVO are negative, evaluation for potential coagulation disorders may be indicated, particularly in young patients and in patients with bilateral RVO, a history of previous thromboses or a family history of thrombosis.

Pars plana vitrectomy, internal limiting membrane peeling, and panretinal endophotocoagulation for macular edema secondary to central retinal vein occlusion

PURPOSE

To investigate the visual and anatomic outcomes in eyes with cystoid macular edema (CME) resulting from central retinal vein occlusion (CRVO) that underwent pars plana vitrectomy, internal limiting membrane peeling, and panretinal endolaser photocoagulation (PPV/MP/EL).

DESIGN

Retrospective, observational case series.

METHODS

Consecutive, nonrandomized patients at the Duke Eye Center who underwent PPV/MP/EL for treatment of CME secondary to CRVO by a single surgeon (S.F.) over the last 5 years were identified and reviewed. Outcome measures include best-corrected visual acuity (BCVA), foveal thickness, and total macular volume (TMV).

RESULTS

Twelve patients were identified. Duration of CRVO before surgery ranged from 3 to 19 months (mean, 12.3 months). Preoperative perfusion status was not ischemic in 6 eyes, ischemic in 5 eyes, and indeterminate in 1 eye. Intravitreal triamcinolone had been administered in 66% and was given at least 4 months before surgical intervention. After surgery, foveal thickness and TMV improved, but BCVA demonstrated only a modest improvement that did not reach statistical significance. At the time of surgery, 50% of eyes were pseudophakic. Of the remaining eyes, visually significant cataracts developed in all 6 (100%) within 1 year after surgery, with 67% of those undergoing cataract extraction within 15 months after PPV/MP/EL.

CONCLUSIONS

PPV/MP/EL performed for CME secondary to CRVO reduced foveal thickness and TMV at final follow-up; however, anatomic improvement did not correlate with a statistically significant improvement in BCVA.

Induction of retinochoroidal venous anastomosis in central retinal vein occlusion with macular edema via a full-thickness retinochoroidal incision

PURPOSE

To report the induction of retinochoroidal venous anastomosis (RCVA) in the treatment of nonischemic central retinal vein occlusion (CRVO) with macular edema via a full-thickness retinochoroidal incision.

METHODS

In nine eyes with nonischemic CRVO and intractable macular edema, one or two full-thickness incisions transacting a major retinal branch vein to the level of inner sclera were made in conjunction with vitrectomy. Fluorescein angiography was conducted to evaluate the formation of functional RCVA. Best-corrected visual acuity (BCVA) and central macular thickness (CMT) were compared before and after the surgery.

RESULTS

The mean follow-up period +/- SD was 12.0 +/- 5.1 months. All nine eyes developed functional RCVA after the surgery. The mean BCVA +/- SD improved from 0.75 +/- 0.30 logMAR (logarithm of the minimal angle of resolution) to 0.55 +/- 0.26 logMAR (P = 0.018), and the mean CMT +/- SD was reduced from 686 +/- 265 microm to 251 +/- 150 microm (P = 0.011). Additional surgery was performed on one eye due to persistent vitreous hemorrhage.

CONCLUSION

Full-thickness retinochoroidal incision appears to raise the rate of successful RCVA formation and may improve the outcome of CRVO with macular edema.

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.

Laser-induced chorioretinal venous anastomosis using combined lasers with different wavelengths

AIM

To evaluate the effectiveness of combined lasers with different wavelengths in creating chorioretinal venous anastomosis (CRVA) in nonischaemic central retinal vein occlusion (CRVO).

METHODS

In this retrospective, noncomparative, consecutive case series, records of all patients with a diagnosis of nonischaemic CRVO who underwent combined laser treatment to induce CRVA and who were followed-up for 6 months or longer were reviewed.

RESULTS

Records of 85 patients (85 eyes) were analysed. These patients were divided into two groups. In group 1 (24 cases, 24 eyes), combined lasers with two different wavelengths (argon blue-green laser combined with Nd-YAG laser were used. In group 2 (61 cases, 61 eyes), combined lasers with three different wavelengths (argon blue-green laser combined with krypton red laser and Nd-YAG laser) were used. Functional anastomosis formed in 13 out of 24 eyes (54%) in group 1 and 47 out of 61 eyes (77%) in group 2. In patients with successful anastomosis, visual acuity improved for two or more lines in 49 out of 60 eyes (82%), with the remaining eyes undergoing no change. There were no serious complications.

CONCLUSION

The use of three laser wavelengths results in the creation of laser anastomosis and the success rate may be higher than when using two wavelengths alone.

Problems with attempted chorioretinal venous anastomosis by laser for nonischemic CRVO and BRVO

PURPOSE

To report the complications and long-term results of laser-induced chorioretinal venous anastomosis in vein occlusions.

PATIENTS AND METHODS

Eight consecutive eyes, 3 with central retinal vein (CRVO) and 5 with branch retinal vein occlusion (BRVO), were observed for up to 5 years after attempted laser-induced chorioretinal venous anastomosis.

RESULTS

Successful chorioretinal venous anastomoses were created in 2 (25%) eyes. Patients had severe complications, including vitreous hemorrhage, choroidal neovascular membrane, choriovitreal neovascularization, rubeosis iridis and neovascular glaucoma.

CONCLUSION

The utilization of a chorioretinal venous anastomosis by laser with proposed laser settings as a therapeutic modality should be further analyzed, and a careful long-term follow-up must be done to avoid vision-threatening complications.

Surgical treatments of central retinal vein occlusion

Central retinal vein occlusion is a common retinal disease with usually severe complications. At present no safe treatment exists promoting the recovery of lost vision. Several surgical approaches to modify the natural course of the disease have been proposed in recent years. These options include laser-induced chorioretinal venous anastomosis, the injection of tissue plasminogen activator into a retinal vein, optic nerve decompression, and vitrectomy for macular edema. Even though all the proposed treatments have not yet been supported by randomized clinical trials, these techniques can be considered as innovative in an area where no effective treatment is available. Larger clinical trials are required to assess both the effectiveness and complication rate of surgical treatments designed to reverse the natural evolution of central retinal vein occlusion.