ADVENTITIOUS SHEATHOTOMY IN THE MANAGEMENT OF RETINAL BRANCH VEIN OCCLUSION: TWO YEARS OF EXPERIENCE

José Garcia-Arumi (Barcelona)

Background: Branch retinal Vein Occlusion is the second most common retinal vascular disorder after diabetic retinopathy, affecting 1.2 % of population older than 49 years. The majority of patients have systemic hypertension, and the mean age is 60 years.

The venous occlusion occurs essentially always in an arteriovenous crossing in the first or second bifurcation. If another location is observed, we have to think in other etiology, like vasculitis. The reason of this location is that the arteriole and the venule share a common adventitial sheath at the arteriovenous crossing. When the thickness of the arteriole wall increases secondary to arteriolosclerosis, the venule is compressed, and flow turbulences, endothelial cell damage and finally thrombotic occlusion occurs. The superotemporal quadrant is the most common affected (63 %).

The patient notices a decrease of visual acuity and metamorphopsia secondary to macular edema and hemorrhages, and sometimes macular ischemia.

The natural evolution of branch retinal vein occlusion is the resolution of hemorrhages between 9 and 12 months. In one third of patients a resolution of the retinal edema is observed, with visual acuity improvement. In the majority of patients, however, a chronic cystoid macular edema produces an important decrease of visual acuity. In 20 - 30 % of patients, retinal ischemia and subsequent neovasculatization occurs.

Purpose: To know if arteriovenous crossing sheathtomy may induce a better anatomic and functional outcome in patients with BRVO.

Methods: 35 patients with BRVO were included in the study. The majority were woman (59 %). Mean age was 58 years, and 85.7 % had systemic Hypertension. Visual Acuity ranged from 20/400 to 20/60, with a mean of 20/200. The time of evolution ranged between 2 and 24 weeks, with a mean of 50 days. Each patient had clinically significant macular edema and hemorrages in the area of the occluded vein. Macular ischemia was observed by FA in 31 % of patients.

Surgical technique included Vitrectomy, posterior hyaloid dissection up to the equator, dissection of the nerve fiber layer with a bended microblade, adventitious sheathotomy with separation of the arteriole from the underlying venule with microblade, spatula or bimanually with special forceps and scissors. At the end of the procedure, fluir-air exchange and 25micrograms of tpa injection were performed in the affected area.

Results: Intraoperatively, we observed thrombus release in 10/35 cases (28.6 %), venous proximal widening in 26/35 cases (74.3 %), and a limited hemorrhage in 5/35 cases (14 %).

Postoperatively, a vitreous hemorrhage was observed in 3 cases, clearing spontaneously. Clinical improvement of macular edema and hemorrhages was observed between 2 weeks and 2 months after surgery in 29/35 patients (82.8 %). Optical coherence tomography (OCT) showed a decrease of macular thickening in 85.7 % of patients.

The visual acuity improved in 30/35 of patients (83.8 %), with an average of 3 lines of ETDRS chart. The mean final VA was 20/40, with a follow-up which ranged between 6 to 26 months.

Discussion: Arteriovenous crossing sheathotomy has shown a better outcome than patients with BRVO followed without treatment and cases treated with laser according to the criteria of BRVO Study. This surgical technique adresses the theoretic pathogenic mechanism, re-establishing the retinal blood flow, and facilitating the clearing of intraretinal edema and hemorrhages. Further studies should be done to determine the degree of visual recovery related to the chronicity of macular edema and hemorrhages, the degree of macular ischemia and the best time for surgery.


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