Age-Related Macular Degeneration Research & Studies
Several new treatments that may help prevent vision lossor even improve visionin people with AMD are under investigation. One promising approach is a combination treatment using Lucentis with photodynamic therapy.
Alternatively, some investigators are exploring "triple therapy": Lucentis, photodynamic therapy, and steroids injected into the eye. Studies are looking at whether combination therapy will produce the same outcomes as Lucentis alone but with fewer doctor visits and less expense.
Others are looking at combining anti-VEGF agents, such as Lucentis or Avastin, with a single dose of radiation to the abnormal blood vessels. A new form of radiation therapy, beta radiation epiretinal therapy, works by delivering a single targeted dose of radiation to the abnormal blood vessels through a device about the size and shape of a fountain pen. This allows the surgeon to focus radiation on the part of the retina affected by AMD.
In a preliminary study, 34 people with wet AMD were given one treatment of radiation plus two intraocular injections of Avastin. At 12 months, the participants were able to see an average of 10 additional letters (equivalent to two lines of vision on the gold-standard Early Treatment of Diabetic Retinopathy Study [ETDRS] eye chart).
Larger studies are under way to test this treatment strategy further. Another promising drug, sonepcizumab, may inhibit blood vessel leakage. Researchers are also investigating a vessel-shrinking cancer drug, endostatin. Other anti-VEGF therapies under investigation include the VEGF Trap-Eye, a drug that when injected into the eye traps VEGF, preventing it from stimulating the VEGF receptors that trigger new blood vessel growth.
Scientists are also exploring the use of small interfering RNAs, or siRNAs, in a process called gene silencing. When siRNAs are injected into the eye, theoretically, they should shut off genes that control VEGF production or that trigger VEGF's action. Research is ongoing, and it is unclear whether in the years ahead these therapies will be widely available or will still be limited to research settings.
Besides continuing development of treatments to prevent new blood vessel growth as well as leakage from blood vessels in the eye, researchers are also studying drugs known as angiostatic corticosteroids (such as anecortave acetate, triamcinolone, and fluocinolone), sometimes in conjunction with other treatments such as photodynamic therapy.
In another development, scientists at Schepens Eye Research Institute affiliated with Harvard Medical School have discovered a "switch" inside blood vessel cells that controls angiogenesis, or new blood vessel growth. Perhaps manipulating these molecular switches will provide a new strategy to prevent or reverse the damage in AMD.
Surgeons at Johns Hopkins have also explored new approaches to the disease. Their attempts to remove abnormal new blood vessels from behind the retina proved not to improve or stabilize vision, but a surgical technique to reposition the retina, known as macular translocation, showed promise.
In macular translocation, the retina is detached, moved, and reattached so that the subfoveal vessels become extrafoveal, where they then can be treated with photocoagulation without harming central vision. Early results showed improvement in up to one third of study participants. However, interest in these surgical approaches has dwindled since the advent of photodynamic therapy and the more potent anti-VEGF drugs, which offer the potential of vision improvement without the substantial risks of surgery.