Branch retinal vein occlusion (BRVO) is a common retinal vascular disease occurring in a significant number of individuals older than 50 years.The most common cause of visual disturbance in BRVO patients is macular edema, which has been reported in 60% of patients. Macular grid laser photocoagulation has been shown to be effective in the treatment of macular edema arising from BRVO. Some eyes are resistant to conventional grid laser treatment, and the conventional treatment is not useful in patients with intraretinal hemorrhages that may interfere with laser photocoagulation. Moreover, several studies have shown that conventional grid laser treatment for macular edema may be associated with complications.

Intravitreal triamcinolone acetonide (IVTA) injection has recently been reported to be effective in the treatment of macular edema of various etiologies.On the other hand, arteriovenous sheathotomy is a surgical method suggested for treatment of macular edema in BRVO patients, and has been reported to be efficacious in patients refractory to conventional focal or grid laser macular photocoagulation.Both treatment modalities have been reported to be associated with reductions in central macular thicknesses and improved visual acuities.

The purpose of the study is to compare the efficacies of arteriovenous (AV) sheathotomy and intravitreal triamcinolone (IVTA) injection in the treatment of macular edema associated with branch retinal vein occlusion (BRVO).

• Macular Edema
• Branch Retinal Vein Occlusion

• Procedure: Arteriovenous Crossing Sheathotomy
• Procedure: Intravitreal Triamcinolone Acetonide Injection

• Experimental: The group 1 patients receive AV sheathotomy for macular edema secondary to branch retinal vein occlusion.
• Active Comparator: The group 2 patients receive IVTA.

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Inclusion Criteria:

• recent onset (within the 6 months prior to enrollment) of macular edema resulting from BRVO
• best corrected Early Treatment Diabetic Retinopathy Study (ETDRS) scores ≤ 40 letters (Snellen equivalent ≤ 20/40
• intraretinal hemorrhages involving the foveal centers
• generalized breakdown of the inner blood-retina barrier, as documented by diffuse fluorescein leakage on angiography, or diffuse thickening of the retina on optical coherence tomography (OCT), with involvement of the foveal center and most of the macular area, and with foveal thicknesses ≥ 250 micrometer

Exclusion Criteria:

• prior history of intraocular surgery including cataract extraction
• prior history of laser treatments including panretinal photocoagulation and focal/grid macular photocoagulation
• prior history of elevated intraocular pressure secondary to steroid treatment
• prior history of glaucoma or ocular hypertension
• presence of comorbid ocular conditions that might affect visual acuity (VA).