18 July 2010
Posted in
Pearls in Ophthalmology
By Rahul Khurana, MD
Central retinal vein occlusion (CRVO) is a devastating condition that can significantly impair vision. Until recently, there were no effective treatments to manage the macular edema associated with CRVO. Over the past six months, there have been three therapeutic modalities supported with Level 1 evidence that can improve vision.
Dexamethasone (Ozurdex, Allergan): The dexamethasone intravitreal implant (Ozurdex) was approved by the FDA in June 2009 for macular edema secondary to CRVO (only approved therapy as of May 2010). The six month trial results showed that 20-30% of patients with either branch retinal vein occlusion (BRVO) or CRVO improved more than three lines at three months. Elevated intraocular pressure (IOP) that required medications occurred in 24% in the Ozurdex treated group after 6 months. The benefits of the implant lasted for approximately three months after which it lost its effect.
Triamcinolone Acetonide: Intravitreal triamcinolone acetonide (IVTA) was studied in the Standard Care versus Corticosteroid for Retinal Vein Occlusion (SCORE) Trial. The SCORE Study was a randomized clinical trial that compared the efficacy and safety of 2 doses (1 mg and 4 mg) of preservative free IVTA (Trivaris, Allergan) with observation among patients with macular edema secondary to non-ischemic CRVO. At one year, 27% of those in the 1 mg IVTA group, 26% of those in the 4 mg IVTA group gained three lines compared to 7% in the observation group. Patients needed an average of two treatments over a 12 month period. Elevated IOP was greater in the 4 mg IVTA group (34% needed IOP lowering medication compared to 20% in the 1 mg and 8% in the observation groups). One of the conclusions from the SCORE study was to treat CRVOs with the 1 mg IVTA dose because of the improved side effect profile.
Ranibizumab (Lucentis, Genentech): CRUISE was a Phase III clinical trial where patients were randomized to 1:1:1 to either sham, 0.3 mg, or 0.5 mg of ranibizumab. Patients who were treated with ranibizumab received six monthly injections. At month 6, 46% of patients receiving 0.3 mg ranibizumab, 48% of those receiving 0.5 mg ranibizumab gained three lines in comparison to 17% receiving the sham injection injections. Patients who were treated with ranibizumab noticed gains in vision as soon as one week after injection.
It is an exciting time to be involved in the management of CRVOs as there are now therapeutic options available for our patients. However, each treatment has its own limitations. Ranibizumab appears to work the best and has a benign safety profile but it requires monthly injections without an endpoint in sight and is extremely costly. The steroid options (Ozurdex and IVTA) requires less frequent dosing (i.e. two IVTA over one year versus six ranibizumab injections over six months) and are cheaper but IOP issues and cataract formation temper their use. Furthermore, the ideal treatment regime is not known and may include a combination approach to optimize outcomes in the future.
