Radial optic neurotomy and peeling of the internal limiting membrane seems to be a surgical treatment for retinal venous occlusive disease that can obtain permanent reperfusion of the retina, in contrast to intravitreal drugs that have only a temporary effect.
Barcelona, Spain-Treating retinal venous occlusive disease with radial optic neurotomy and peeling of the internal limiting membrane can obtain permanent reperfusion of the retina, in contrast with intravitreal drugs that do not have the same effect, according to Jose Garcia-Arumi, MD.
"Macular edema is the main cause of decreased vision in retinal venous occlusive disease," said Dr. Garcia-Arumi, professor of ophthalmology, Universitat Autonoma de Barcelona, Institut de Microcirurgia Ocular, Barcelona, Spain. "The goals of current treatment are to perfuse the thrombosed vein to obtain drainage of the retinal circulation, reduce the permeability of the macula, and increase the vitreoretinal fluid exchange.
"Some surgical options have been tried in branch retinal vein occlusion that include vitrectomy with and without peeling of the internal limiting membrane, surgical decompression, and intravitreal or vascular injection of recombinant tissue plasminogen antigen (rt-PA)," Dr. Garcia-Arumi said.
Dr. Garcia-Arumi and associates also compared sheathotomy with triamcinolone acetonide. One group of patients underwent sheathotomy alone, the second group was treated with combined therapy, and the third group received intravitreal triamcinolone. In the surgery group, a special forceps and scissors were used during a bimanual technique, he said. A bent microblade was used to create a dissection plane, and a spatula was used to enlarge the dissection of the arteriole to provide better access for the forceps for displacing the arteriole and better access to the dissection plane between vessels. In some cases, he said, the thickened tissue between the vessels is difficult to dissect.
"This bimanual technique allows complete dissection and decompression of the vein," Dr. Garcia-Arumi said.
He provided some representative case reports from the study. In one case, the patient had 20/20 visual acuity (VA) 4 months after surgery. In a second patient, the dilated and tortuous vein was one-third the preoperative size after surgery and the patient had 20/40 acuity. In a patient with retinal vein occlusion complicated by cystoid macular edema, the patient had 20/30 VA following surgery, with resolution of the macular edema. In another case, the patient was treated with triamcinolone, but the macular edema recurred after 6 months.
In this study, VA improved four lines in the surgical groups and 2.5 lines in the medical group.
"The release of the thrombus was a very good indicator of the improvement of the visual acuity in those patients," he said.
Generally, patients who underwent surgery had better outcomes. Those who received triamcinolone initially had good outcomes, but the efficacy of the drug decreased over time. The only way to determine the efficacy of the surgical technique is to conduct a clinical trial, he said.
"Our recommendations include selection of patients with a visual acuity of less than 20/60 and a foveal thickness that exceeds 400 μm," Dr. Garcia-Arumi said. "We tend to perform the surgery as early as possible in the disease stage because, by 3 months after onset, reperfusion occurs infrequently.
"We separate both vessels completely and try to release the thrombus," he said. "Using SLO angiography intraoperatively is the only way to know if reperfusion of the vein has been achieved."
In central retinal vein occlusion, neural decompression can be tried from an internal approach or by an external approach using radial optic neurotomy. In a comparison of three published studies, all patients had low VA initially, and these patients historically have the worse outcomes, he said.
The VA improved in half of the cases by two or more lines, which is better than the natural evolution of the disease, he said. Chorioretinal anastomosis occurred in more than half of the cases with a low incidence of anterior segment new vessels.
Dr. Garcia-Arumi described a case of macular edema with 1,000 μm of foveal thickness in which there was perfuse retinal anastomosis postoperatively that drained the retinal circulation through the choroid and through the nasal neurotomy. In another case with almost 1,000 μm of foveal thickness, VA improved in 3 months despite changes in the retinal pigment epithelium.
A combination technique of this surgery with radial optic neurotomy was performed. The results obtained were similar to those achieved with radial optic neurotomy alone, according to Dr. Garcia-Arumi.
"The best results were obtained with the combination technique," he said.
In one-third of the cases in which triamcinolone was administered, an increase in IOP occurred.
Regarding the role of dissection of the internal limiting membrane in central vein occlusion, he pointed to two publications that supported dissection. A limitation of those studies was the absence of a control group. Dr. Garcia-Arumi and colleagues evaluated the technique and compared it with radial optic neurotomy, peeling of the internal limiting membrane, and triamcinolone with a control group. He used a 25-gauge microblade to perform nasal optic neurotomy. Triamcinolone, which was used to facilitate visualization of the retinal surface, clearly demarcated the plane of dissection between the retina and the internal limiting membrane, according to Dr. Garcia-Arumi. As wide of a dissection as possible was desired up to the temporal arcades to allow better fluid exchange between the retina and the vitreous cavity.
Good results were obtained in the patients in which the internal limiting membrane was dissected at 3 and 6 months postoperatively. The volume of the macular edema and the optic disc chorioretinal anastomosis were similar in both groups, however. The VA was superior in the dissection group compared with the control group, with an improvement of four lines of vision at 3 months and six lines at 6 months, respectively.
A multicenter clinical study is ongoing to compare eyes treated with radial optic neurotomy, triamcinolone, and control eyes.
"Chorioretinal anastomosis in radial optic neurotomy increased the visual acuity and decreased the incidence of anterior segment new vessels," Dr. Garcia-Arumi said. "There is a transient effect of the triamcinolone in that the IOP increases and cataract develops in most patients. The combined treatment of radial optic neurotomy and peeling of the internal limiting membrane obtains the best results. If we obtain reperfusion during the surgery, we will have a permanent effect, which is not what is obtained with intravitreal drugs."