Evaluation of Macugen Treatment of Macular Edema Due to Branch Retinal Vein Occlusion

Retinal venous occlusive disease, which includes central retinal vein occlusion (CRVO) and
branch retinal vein occlusion (BRVO), is second only to diabetic retinopathy as a cause of
vision loss due to retinal disease. The main cause of vision loss in all of these disorders
is the development of macular edema. Current clinical practice based on randomized
controlled clinical trials (ETDRS, BVOS) employs laser photocoagulation, either in a focal
or grid pattern, to treat macular edema associated with diabetic retinopathy and branch
retinal vein occlusion. Unfortunately, laser photocoagulation is ineffective in central
retinal vein occlusion (CRVO), and no proven therapy exists for CRVO.

The pathogenesis of macular edema in retinal vascular diseases is generally accepted to be
increased levels of vascular endothelial growth factor (VEGF) due to ischemic or other
stimuli. VEGF is known to be one of the most potent stimulators of vascular leakage in
humans. Therefore, it seems sensible to study inhibition of VEGF to reduce vascular
leakage, reduce macular edema, and improve vision in these retinal vascular disorders.

Phase 2 randomized, controlled clinical trials of Macugen in diabetic macular edema and in
macular edema associated with CRVO have been conducted. In the diabetes trial, patients
treated with Macugen had improved vision, reduced macular edema as measured by optical
coherence tomography (OCT), and reduced need for laser treatment compared to patients
treated with sham injections. In the CRVO trial, patients treated with Macugen 1 mg every 6
weeks for 24 weeks had improved vision and reduced macular edema at week 30 compared to
sham. This is the first randomized trial of treatment for CRVO to show a benefit over
control. Based on these positive findings, we plan to study Macugen treatment of macular
edema due to BRVO.

Inclusion Criteria:

- Macular edema secondary to BRVO involving the foveal center in male or female
patients at least 18 years of age

- Duration of BRVO macular edema less than 6 months prior to baseline visit

- Best corrected ETDRS visual acuity 20/40-20/320 (Snellen equivalent) using the 4
meters testing method.

- Central foveal thickness greater than or equal to 250 microns using the OCT-3

- Less than 25% of foveal capillary ring disruption

- Less than 2 disc areas of capillary non-perfusion within 1000 microns of the foveal
center

- Absence of hemorrhage or lipid in the foveal center

- Investigator comfortable deferring macular laser for 18 weeks from baseline and
intravitreous steroid for 36 weeks from baseline

Exclusion Criteria:

- Ocular conditions other than BRVO related macular edema such as significant cataract,
diabetic retinopathy, AMD, glaucoma, uveitis, epiretinal membrane, vitreomacular
traction or tumor.

- Intraocular surgery within past 3 months

- Significant enlargement of foveal avascular zone(>25% disruption of capillary ring)
or greater than 2 disc areas of nonperfusion within 1000 microns of foveal center.

- Likelihood of evidence driven indication for peripheral photocoagulation in the next
6 months.

- Patients who have shown evidence of spontaneous improvement within the preceding 3
months, as determined by an improvement of >15 letters of vision or thinning of the
Center Point on OCT of >20% from baseline determination

- Prior grid laser within 4 months of baseline or more than one prior grid laser
treatment.

- No prior intravitreous or periocular steroid injections in the study eye.