Laser-induced Chorioretinal Venous Anastomosis Research Articles

Factors Promoting Success and Influencing Complications in Laser-Induced Central Vein Bypass

To evaluate the factors influencing the successful creation of a laser-induced chorioretinal venous anastomosis (L-CRA) and those involved in the development of complications. Interventional cohort study. Fifty-five patients with a nonischemic central retinal vein occlusion (CRVO) who were randomized to receive an L-CRA from the total of 108 who completed the follow-up period of the Central Vein Bypass Study. Patients who were randomized to L-CRA were followed up for an 18-month period. They were stratified in 2 sets of 2 cohorts: those who did or did not demonstrate an L-CRA and those who did or did not demonstrate neovascular complications at the site of the L-CRA. Subgroup analysis was performed to determine what factors influenced the creation of an L-CRA and the development of complications at each individual laser site. Identification of systemic and local ocular factors associated with increased success rates of L-CRA creation and those involved with an increased risk of neovascular complications. Younger age (P = 0.03), better baseline visual acuity (P = 0.04), and the absence of hypertension (P = 0.001) were systemic features associated with an increased chance of demonstrating a successful L-CRA at each site, whereas sex and duration of the CRVO were not. The position of the L-CRA site did not influence the outcome; however, evidence of rupture of the vein wall at the time of the attempt was associated with a higher chance of success (P = 0.008). Increased risk of neovascularization, which occurred at 12 sites in 10 eyes, was associated with higher central venous pressure before treatment (P = 0.03), prolonged fluorescein transit time (P = 0.0001), and the presence of some capillary nonperfusion (P = 0.01). Younger age, better baseline visual acuity, and the absence of hypertension were associated with an improved success rate, as was evidence of rupture of the vein wall. High baseline central venous pressure, prolonged fluorescein transit time, and the presence of any retinal ischemia were associated with a higher incidence of neovascular complications. Proprietary or commercial disclosure may be found after the references.

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

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). Observational case report. 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. 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.

The Central Retinal Vein Bypass Study: A Trial of Laser-induced Chorioretinal Venous Anastomosis for Central Retinal Vein Occlusion

To evaluate the effectiveness of a laser-induced chorioretinal venous anastomosis (L-CRA) as a treatment for nonischemic central retinal vein occlusion (CRVO). Prospective, randomized, controlled, multicenter clinical trial. A total of 113 consecutive patients with a nonischemic CRVO of >3 months' duration and visual acuity of < or =20/50. Patients were randomized to L-CRA (58 patients) or conventional care (55 patients). They underwent standardized retinal photography, fluorescein angiography, and ophthalmic examinations, together with standardized assessments of best-corrected visual acuity, performed by masked visual acuity assessors using Early Treatment Diabetic Retinopathy Study protocols. Analysis was performed by intention-to-treat. The primary outcome measure was change in visual acuity at 18 months. Secondary outcomes were progression of retinal ischemia and rates of adverse events. A total of 53 control patients and 55 treatment patients completed the study. The 2 groups were comparable for age, age- and gender-adjusted mean visual acuity, and most other parameters. In the treated group of 55 patients, 42 (76.4%) developed an L-CRA. Over the 18-month follow-up period, treated eyes had an 8.3 letter mean improvement from baseline compared with control eyes (P = 0.03). Treated eyes that developed a functional L-CRA achieved an 11.7 letter mean improvement from baseline over the control group after 18 months (P = 0.004). Conversion to the ischemic CRVO category occurred in 20.8% of control eyes and in 9.6% of treated eyes overall (P = 0.33). Of the treated group who developed an L-CRA where the retinal ischemia was due to progression of the CRVO, 4.9% progressed to the ischemic category (P = 0.03). Neovascularization developed at the site of the L-CRA in 10 of 55 treated eyes (18.2%). Vitrectomy surgery was required by 5 of 55 treated eyes (9.1%) because of macular traction or nonresolving vitreous hemorrhage. Chorioretinal venous anastomosis was created in 76.4% of eyes with nonischemic CRVO in this study. Eyes that developed an anastomosis had a significant improvement (11.7 letters) in final visual acuity after 18 months, compared with eyes in the control group (P = 0.004). Complications were managed successfully with careful follow-up and early intervention.

Traitement par hémodilution des occlusions de la veine centrale de la rétine

Evaluate the effects of hemodilution in the treatment of central retinal vein occlusion (CRVO). We carried out a retrospective, noncomparative study of 25 patients presenting unilateral CRVO, treated with one to three hemodilution sessions. The patients were re-examined in the 1st, 2nd, 3rd, 6th and 12th months following treatment with measurement of visual acuity, fluorescein angiography, and optical coherence tomography. Our study included 17 men and eight women, averaging 63 years of age (range, 35-87 years), and monitored for an average of 7 months (range, 3-12 months). After the 6th month following treatment, average visual acuity improved compared to initial visual acuity. Initial visual acuity of less than 1/10, with the existence of poorly irrigated areas in the angiography, presented negative prognosis factors. The number of hemodilutions did not produce a significant difference in final visual acuity. No serious complications due to hemodilution were observed. Treatment of CRVO is subject to debate. Some practitioners recommend against treatment, while others advocate intervention and offer laser-induced chorioretinal venous anastomosis. Surgical vitrectomy and radial optical neurotomy, with or without injection of triamcinolone, await evaluation. Hemodilution may offer a therapeutic approach to this pathology, in which the etiopathogenesis is not yet recognized, but in which blood viscosity plays a key role. This treatment is well tolerated. Hemodilutions appear to have beneficial effects in treating CRVO, whatever the number of hemodilutions used. This study should be confirmed by a prospective study using an untreated control group.

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

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

Chirurgische Therapie retinaler Venenverschlüsse

Retinal vein occlusions are the second most common vision threatening retinal vascular disorders. Our therapeutic armamentarium for functional improvement was very limited in the past for all types of retinal vein occlusions (branch, central and hemi-central retinal vein occlusion). Also pathomechanism and risk factors are not completely understood yet. Argon-laser-photocoagulation can prevent the development and treat neovascularizations successfully, but is unable to improve visual function in most cases. Thrombolytic therapy applied systemically is limited due to serious side effects but may be helpful when injected intraocularly. Isovolemic hemodilution may be efficacious in central retinal vein occlusion (CRVO). The creation of a laser-induced chorioretinal venous anastomosis showed serious complications. Since 1999 numerous reports on successful surgical techniques were published. It could be shown that the dissection of the adventitial sheath with separation of the artery from the vein at the arteriovenous crossing where branch retinal vein occlusion occurs can re-establish the retinal blood flow with reduction of macular edema. But it is still unclear which step of the surgery (vitrectomy, ILM-peeling, sheathotomy) is causative for the results. A new surgical approach in CRVO is the radial optic neurotomy (RON). This technique was primarily performed under the hypothesis of decompression of the central vein by cutting the scleral ring. Meanwhile there is some evidence that the formation of chorioretinal shunts may be the decisive factor in cases of successfully performed RON. Due to inconsistent and rare data this surgical procedure needs further evaluation. Another surgical option is the cannulation of the occluded vein. This technique seems to be feasible but the clinical results still have to be proved. Despite several uncertainties and open questions, surgical techniques are likely to overcome the desolate therapeutic situation for retinal vein occlusion of the past.

Clinical study of laser-induced chorioretinal venous anastomosis

To test the effectiveness and safety of laser-induced chorioretinal venous anastomosis in the treatment of nonischemic central retinal vein occlusion (CRVO), and also the effectiveness of the preventative measures for complications associated with the treatment. Laser-induced chorioretinal venous anastomosis was performed on 34 cases, 35 eyes with nonischemic CRVO. During the treatment, preventative measures for complications were taken as follows: (1) Patients with total retinal papillary nonperfusion area of less than 5 DA were selected to receive the treatment. (2) Treatment sites must be at least 3 PD away from the optic disc and 4 PD away from the macula. (3) At most 2 argon laser shots were attempted over each treatment site, to avoid severe laser damage. (4) Scattered argon laser photocoagulation was done over the drainage area of the vein distal to the treatment site, in order to prevent neovascular complications in case distal vein occlusion occur. During the 3 approximately 12 months (average 6 months) follow-up, successful anastomosis formed in 28 eyes out of 35 eyes (80%) with a mean of 2.4 attempts to create an anastomosis in each eye. With successful anastomosis, retinal hemorrhage started to be absorbed gradually 2 weeks after the treatment, and almost entirely absorbed 1 approximately 2 months later. Retinal edema also alleviated. Visual acuity improved in 20 out of 28 eyes (71%), and remained unchanged in the rest of the patients with successful anastomosis. In comparison with the natural course of the disease, our treatment has improved both the visual prognosis and the retinal damage caused by the disease. No serious complications occurred in these patients with successful anastomosis. Anastomosis failed to form in 7 cases (7 eyes), among which, 2 eyes developed serious neovascular complications. CRVA treatment is effective in the treatment of non-ischaemic CRVO. With proper preventative measures for complications associated with the treatment, the safety of the treatment can be increased prominently, but serious neovascular complications was not entirely prevented.

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.

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

Purpose To evaluate the long-term outcomes of a modified technique for laser chorioretinal venous anastomosis in nonischemic central vein occlusion (CVO). Design Prospective, noncomparative, consecutive case series. Participants Nineteen eyes of 19 patients. Methods Nineteen consecutive eyes with nonischemic CVO were observed for a mean period of 48 months after attempted laser-induced chorioretinal venous anastomosis therapy using a technique modified intentionally to avoid vein wall rupture. Main outcome measures Anastomosis patency, visual acuity, maintenance of nonischemic status, and complications were measured. Results At least one patent anastomosis developed eventually in 19 of 19 eyes (100%). Two anastomoses developed in 5 of 19 eyes (26%). There were one or two nonfunctioning sites in 8 of 19 eyes (42%). The maximum number of treatment attempts in a single eye was four. Snellen visual acuity was unchanged in 3 of 19 eyes (16%) and improved from 1 to 11 lines (mean improvement, 5 lines) in 16 of 19 eyes (84%) during the mean follow-up period of 48 months. Nineteen of 19 eyes (100%) maintained nonischemic status. Treatment complications were limited to localized preretinal fibrosis. Conclusions Rupture of the vein wall is not required to form a functioning laser-induced chorioretinal venous anastomosis in eyes with nonischemic CVO. A technique modified intentionally to avoid vein wall rupture seems to be safer and more predicable.

Optimal Laser Power to Rupture Bruch's Membrane and the Retinal Vein in the Pig

For laser-induced chorioretinal venous anastomosis to become a viable treatment option for perfused central retinal vein occlusion, laser parameters must be refined to more reliably create venous anastomoses while minimizing complications. The aim of this study was to determine the lowest argon laser power at which Bruch's membrane and the retinal vein are ruptured in 100% of attempts in the porcine eye. Testing was performed on 6 eyes of 3 Yorkshire Cross pigs, using an argon green laser. The spot size was 50 microm and the duration was 0.2 seconds for all applications. Twelve laser powers were tested, from 0.5 to 6 W, increasing by increments of 0.5 W. Light microscopy was used to determine the frequency of rupture of Bruch's membrane and the retinal vein for each power. The rupture rate of Bruch's membrane was 0% at 0.5 W, 5% at 1.0 W, 20% at 1.5 W, 70% at 2.0 W, and 100% for all powers from 2.5 to 6.0 W. The rupture rate of the retinal vein was 0% at 0.5 W, 5% at 1.0 W, 30% at 1.5 W, 60% at 2.0 W, 80% at 2.5 W, and 100% for all powers from 3.0 to 6.0 W. Argon green laser powers of at least 2.5 and 3.0 W were necessary to rupture Bruch's membrane and the retinal vein, respectively, with a 100% success rate in the porcine eye. Because patients with central retinal vein occlusion have secondary retinal edema and may have lenticular opacity, higher laser powers may be required to achieve a 100% rupture rate of these structures.

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.

Successful erbium:YAG laser-induced chorioretinal venous anastomosis for the management of ischemic central retinal vein occlusion

Central retinal vein occlusion (CRVO) is a disorder with potentially blinding complications, particularly when associated with retinal ischemia. There is no reliable treatment for ischemic CRVO. We developed a new approach for ischemic cases of CRVO consisting of vitrectomy, posterior hyaloid detachment, and four erbium:YAG laser-induced chorioretinal anastomoses, one in each quadrant. We report two cases of ischemic CRVO treated with this approach, with initial visual acuity of count fingers at 30 cm and hand movements respectively. After the surgery, there was resolution of hemorrhages and macular edema and visual improvement to 20/400 in the first case and to 20/180 in the second case. In both cases, there was successful creation of chorioretinal anastomoses, and there was no anterior segment neovascularization or other complications related to the surgery. This treatment shows promise in the management of the ischemic cases of CRVO, and further evaluation is justified.

Choroidovitreal neovascularization following laser-induced chorioretinal venous anastomosis

There has been a great deal of interest in the use of the argon laser to produce chorioretinal venous anastomoses in the treatment of vision-threatening macular edema following central retinal vein occlusion. Complications associated with this procedure include: choroidal neovascularization, vitreous hemorrhage, preretinal fibrosis and traction retinal detachment, and choroidovitreal neovascularization. We report a case of choroidovitreal neovascularization following laser-induced chorioretinal venous anastomosis formation in a patient with central retinal vein occlusion.

Laser-induced chorioretinal venous anastomosis for non-ischaemic hemi-central vein occlusion.

To assess the effectiveness and complications of laser-induced chorioretinal venous anastomosis performed on eyes with non-ischaemic hemi-central retinal vein occlusions (hemi-CRVO). Fourteen eyes with a hemi-CRVO which reduced the visual acuity to 6/24 or less were treated with argon laser photocoagulation in an attempt to create a chorioretinal venous anastomosis between a retinal vein and the choroidal circulation. Laser anastomoses were successfully created in six eyes (43%) and required a mean of 1.8 attempts in each eye. Of the eyes that developed an anastomosis, four had significant visual improvement. The distal retinal venous segment closed off in five eyes and these had prophylactic segmental argon pan-retinal photocoagulation performed. Two eyes had localized fibrovascular proliferation. No permanent vision-threatening complications were observed in any of the 14 eyes over the follow-up period. Successful anastomosis between the retinal and choroidal circulation in eyes with hemi-vein occlusions may reduce macular oedema and improve vision. Complications of the technique are significant and a randomized clinical trial is due to commence which may clarify the suitability of this treatment.

Fundus photographic, fluorescein angiographic, and indocyanine green angiographic signs in successful laser chorioretinal venous anastomosis for central retinal vein occlusion

Objective To describe the fundus signs and angiographic signs that accompany development of a laser-induced chorioretinal venous anastomosis in central retinal vein occlusion and to describe the chronology of the signs. Design Noncomparative, consecutive case series. Participants Fifteen eyes of 15 patients were treated. Intervention The argon laser was used in the original method of McAllister and Constable to form an anastomosis in five eyes, and the modified method of McAllister involving the argon laser followed by the YAG laser was used for ten eyes. Main outcome measures Changes in vessel diameters, retinal blood flow, and morphology of anastomosis over time as documented photographically and angiographically. Results The earliest fluorescein angiographic sign of success is a hyperfluorescent spindle at 1 week. The earliest indocyanine green angiographic sign is direct connection of retinal venous and choroidal venous circulations at 2 weeks. The earliest fundus photographic and, hence, ophthalmoscopic sign is asymmetry in venous diameter at the disc at 3 weeks. No sign is present in all successful cases. The most commonly observed sign is fluorescein flow around a corner in a retrograde direction toward the anastomosis in 80% of cases. Drainage of only a fraction of the retina occurred in 93% of cases. Fifteen eyes with successful anastomoses had mean improvement of 2.3 ± 2.4 (standard deviation [SD]) Snellen lines of best-corrected visual acuity compared to 0.2 ± 2.3 (SD) lines for 9 eyes with unsuccessful anastomoses ( P = 0.0439). Conclusion Recognition of the variety and typical chronology of postoperative fundus and angiographic signs in laser-induced chorioretinal anastomosis will help prevent premature retreatment and guide appropriately timed additional treatment for failed initial attempts. Fluorescein angiography and indocyanine green angiography are necessary components of intensive postoperative follow-up of these patients. The follow-up care is more difficult than the technical aspects of the surgery itself. Successful anastomoses help by taking part of the flow away from the compromised central vein, not by providing global venous bypass. This technique remains controversial, unproven, and in need of a randomized clinical trial to determine its role in the management of nonischemic central retinal vein occlusion.

Laser-induced chorioretinal venous anastomosis for nonischemic central retinal vein occlusion: evaluation of the complications and their risk factors

PURPOSE: To evaluate the complications of laser-induced chorioretinal venous anastomosis in nonischemic central retinal vein occlusion (CRVO) and to identify the associated risks. METHODS: A retrospective consecutive series of 91 eyes (91 patients) with nonischemic CRVO with a mean ± SD duration of 15.0 ± 15.2 weeks (range, 3 to 72 weeks )and corrected visual acuity reduced to 20/100 or less because of perfused macular edema were reviewed. All eyes had one or more anastomotic attempts using argon laser (combined with Nd-YAG laser in 46 eyes) and a minimum of 12 months of follow-up. RESULTS: Successful chorioretinal venous anastomoses were created in 49 eyes (54%). Eighteen eyes (20%) had neovascular complications. These consisted of intravitreal, intraretinal, and subretinal neovascular membranes and were significantly associated with retinal ischemia ( P < .001). There was avascular fibrous tissue proliferation at the anastomotic site in eight eyes (9%), and it was not associated with retinal ischemia ( P = .727). No eye developed further capillary nonperfusion once an anastomosis became functional. A chorioretinal venous anastomosis was associated with improved vision ( P < .001); 84% of eyes had an average ± SD improvement of 4.3 ± 3.8 lines (range, 2 to 20 lines), with the remaining 16% having no improvement or reduced vision. CONCLUSION: The major vision-threatening complication of laser-induced chorioretinal venous anastomosis for nonischemic CRVO is neovascular membranes occurring at the anastomotic site; these are associated with retinal ischemia. Prompt laser photocoagulation to areas of retinal ischemia that develop after the anastomotic attempt has been made may reduce the risk and severity of this complication.

Epiretinal Membrane and Traction Retinal Detachment Complicating Laser-induced Chorioretinal Venous Anastomosis

To report a patient with a sight-threatening complication of laser-induced chorioretinal venous anastomosis for treatment of central retinal vein occlusion. A 69-year-old woman with a nonischemic central retinal vein occlusion underwent focal argon laser photocoagulation treatment to create a chorioretinal venous anastomosis. Massive preretinal fibrosis and traction retinal detachment developed over the area of argon laser photocoagulation, which required vitreous surgery. Laser-induced chorioretinal venous anastomosis to treat central retinal vein occlusion can be associated with severe complications, underscoring the need for additional study of this new treatment modality.

Laser-induced chorioretinal venous anastomosis for treatment of nonischemic central retinal vein occlusion.

To determine whether a chorioretinal venous anastomosis could be created in humans and to evaluate the influence this has on patients with nonischemic central retinal vein occlusions in whom progressive visual loss developed. Retrospective study. A total of 24 patients with nonischemic central retinal vein occlusions and progressive visual loss. An attempt was made to create a chorioretinal venous anastomosis using laser photocoagulation to enable obstructed venous blood to enter the choroid, thus bypassing the site of occlusion. Visual acuity, funduscopic appearance, and rapid sequence fluorescein angiograms. A successful chorioretinal venous anastomosis was created in eight cases (33%), with improvement in visual acuity and resolution of the funduscopic appearance of venous occlusion in all eight cases. Of the 16 patients (67%) in whom an anastomosis was not successfully created, the ischemic form of central retinal vein occlusion developed in five (31%), and eight (50%) were left with various degrees of macular damage and reduced visual acuity. Peripheral chorioretinal venous anastomoses can be created in a nonischemic central retinal vein occlusion and appear to be well tolerated. This technique may have some value in the treatment of patients with this condition; however, to address this fully, a properly constructed randomized prospective clinical trial will need to be performed.