The most prevalent cause of Macular Degeneration can be attributed to the wet, or neovascular Macular Degeneration. Accounting for about 10-20% of all known cases, wet AMD is responsible for 75% of loss of vision in the population. Previous treatment of Macular Degeneration was achieved through laser therapy, which burned the affected parts of the retina to prevent further loss of vision. Tiny blood vessels that grow as a result of AMD are structured differently to other blood vessels. They are the reaction of a retina that has been starved of oxygen. Vascular endothelial growth factor, or VEGF is responsible for the fresh growth in the retina of weak and leaky blood vessels. These malformed blood vessels actually serve no purpose other than to promote further damage to the retina. New treatments have been developed which have shown headway into preventing the eye from creating the new and damaged blood vessels because of VEGF.
Discussion of the newest treatments for AMD
Macular degeneration treatment first started as far back as the 1970’s which made use of a ‘hot’ laser, to try and prevent the spread of weak blood vessels through the retina by burning the troubled spots. This treatment was only partially successful at preventing further loss of sight. Untreated patients would commonly lose 7 lines of vision as opposed to treated patients losing 5 lines over a period of 5 years. The treatment could also not guarantee against the recurrence of new damaged blood vessel growth. These new blood vessels were likely to resume growing within the first 6-12 months of treatment.
Photodynamic Therapy (PDT)
PDT is a newer method of macular degeneration treatment which still attempts to target the problem blood vessels with a laser. Photocoagulation burned indiscriminately, whether the area of the retina was healthy or suffering from neovascular degeneration. PDT works by first injecting the patient’s eye with a photosensitizing chemical that responds differently to varying wavelengths of light, the laser being the source of the light. It actively targets the damaging blood vessels rather than the healthy surrounding tissue. Even though tissue destruction is still occurring through burning, the technique has still been dubbed as a ‘cold’ laser treatment. PDT therapy still suffers from recurrence of the condition. On average a patient can require 2-3 treatments within the first year, and in subsequent years may require a further 1 or 2 treatments.
Tumors do better when they have ready access to a supply of blood. The constant influx of nutrients aids in their development and ability of the cells to replicate. The growth hormone released by the retina is the same as the one released by tumors. A few very clever doctors decided to attempt to use cancer treating anti-VEGF pharmaceuticals as a way to slow down the spread of wet AMD. As a result, the current therapy is to treat patients with a monthly dose of anti-VEGF drugs such as Macugen or Avastin. Constant injections are required to halt the growth. Despite this, the results are much more promising than the ones obtained with laser therapy. It is not uncommon for injections to actually increase the quality of vision by one or two lines rather than slowing down the degeneration.