Vein occlusion is the second most common retinal vascular entity (diabetic retinopathy is the most common).
In the past, treatment was limited to specific patients and showed modest efficacy.2,3 Recent clinical trials, however, have resulted in more frequent use of agents that inhibit vascular endothelial growth factor (VEGF), intravitreal steroid injections, and FDA approval of a new steroid implant. These treatment options offer new hope for patients with macular edema secondary to central and branch retinal vein occlusion (CRVO and BRVO, respectively).
Two of the largest studies that looked at the treatment of macular edema in patients with vein occlusion date back more than 20 years. The Branch Vein Occlusion Study (BVOS) and Central Vein Occlusion Study (CVOS) evaluated focal laser for the treatment of macular edema associated with BRVO and CRVO.2,3
The CVOS looked at subjects with best-corrected visual acuity of 20/50 or poorer. Treated subjects showed angiographic evidence of improvement, but there was no improvement in visual acuity.3
Intravitreal steroid injection
Many small-scale studies and case reports show a potential benefit of intravitreal ster-oid injections for treating macular edema associated with BRVO and CRVO.4,5
To date, the Standard Care versus COrticosteroid for Retinal Vein Occlusion (SCORE) Trial is the largest study that has compared intravitreal steroid injection with standard-of-care treatment (macular grid laser for BRVO, observation for CRVO) for macular edema associated with vein occlusion. Researchers randomly assigned about 700 subjects to receive standard-of-care treatment, a 1-mg intravitreal injection of triamcinolone acetonide (Kenalog), or 4 mg of intravitreal triamcinolone acetonide. Subjects were evaluated and re-treatment was assessed every 4 months.6,7
The SCORE-BRVO 3-year study determined that laser was most effective for treating macular edema associated with BRVO. There were no statistically significant differences in outcome when comparing patients who received intravitreal steroid injection with those treated with laser. At 3 years, 29% of the patients treated with laser experienced three or more lines in improved visual acuity, as did 26% of those who received 1 mg of triamcinolone acetonide and 27% of those who received 4 mg.6 Also, there was a greater incidence of cataract formation and increased IOP among patients treated with steroids.6