Bryan Adams, in one of his songs said, ”Look Into My Eyes”, you will see what you mean to me.”
Can we continue to say this even if we age? Will our vision still remain as good as ever? These are some questions that we need to ask if we do not take good care of ourselves and also our eyesight. With aging many complications occur that can lead to vision loss. Macular Degeneration is one of them and it is the leading cause of severe vision loss in people age 60 and above.
Images are projected at the macular of the retina which is the most critical part for sharp visual acuity. Diseases can occur at the macular, with age-related macular degeneration being the leading cause. There are two types of age-related macular degeneration: non neovascular (dry or non new vessels formation) and neovascular (wet or new vessels formation) with the wet type being the predominant cause of severe visual loss in age-related macular degeneration.
The natural history of untreated wet type is poor with progressive loss of central vision. Laser treatment is only of benefit in only a small proportion of patients. Laser may result in destruction of retinal tissue and the recurrence rate following successful treatment is high.
The diagnosis and classification of macular degeneration is based on the findings on fluorescein angiography. This is a dye that is injected into the blood stream and a series of photos showing the flow of blood vessels in the eye are taken. The study of this mapping of blood vessels showing the leakage can determine the extent and type of destruction caused, hence treatment can be applied accordingly. With the dry type, there is no new vessels formation; therefore no leakage of blood can be picked up. Dry type is not amenable to any form of treatment.
This is of benefit to in the treatment of milder form of macular degeneration. In the long-term, the visual outlook is better with laser application than without. An instant and irreversible loss of central vision occurs immediately following such treatment. Many surgeons do not perform such treatment for this reason.
Following successful laser treatment, the risk of recurrent disease is high and the risk increases with time. The majority of recurrences are not possible to have repeated laser.
This modality, originally used in tumor therapy, has been evaluated in the treatment of the wet type. The pathological blood vessels in the wet type selectively take up a dye called verteporfin injected into the blood stream through the arm. Photo activation of the dye is accomplished by selectively irradiating the new blood vessels by a low-power infrared laser (different wavelength to laser photocoagulation). This results in the focal damage to the blood vessels. It has minimal effect on the rest of healthy tissue. This form of therapy is showing beneficial results in selected cases. This drug is expensive.
Surgery can achieve removal of the new vessels. However the results are poor due to damage to the surrounding tissue.
Interferon, an anti angiogenic agent used in cancer therapy has not been shown to be of benefit in the management of neo vascular age-related macular degeneration. Isolated reports have suggested that radiotherapy is of benefit. Radiotherapy is under evaluation with randomized controlled trial.
Following successful laser treatment, the risk of recurrent disease is high and the risk increases with time. The majority of recurrences are not amenable to further laser treatment.
The risk of bilateral wet type is high. The risk of fellow eye involvement over 5years varies from 7-8%.The is no proven method of preventing the development of new vessels formation. There is a suggestion from laboratory experiments and dietary analysis that vitamin and mineral supplements may play a role in prevention. The result of further research to evaluate the role of dietary supplements is awaited.