ARMD: Treatment & Research
Written by Luke Lindsell and G. Lowther, O.D. PhD.
ARMD has received much attention in the public forum. Segments on nightly news programs to articles in prominent newspapers commonly highlight this debilitating disease. This is not surprising when one considers the number of people who do and potentially might suffer from ARMD's effects. Yet, these reports are often discouraging because there is no cure for either dry or wet ARMD. Due to the increased public interest however, the research community has stepped up their efforts in finding a solution. Even though there are no definitive conclusions, early results are promising. Despite the lack of a cure, several therapeutic procedures do exist that can potentially slow or stop the advancement of ARMD. In this section we have highlighted some of the more prominent procedures available and some that are still in the research phase. ARMD, while not curable, can be managed with proper education and regular visits to your eye care specialist.
Of all the possible techniques available for treating wet ARMD with choroidal neovascularization, this is probably the most common. A laser is used to cauterize or burn away the developing vascular net. The downside to this treatment is that it leaves a small scar which results in a blind area. This occurs because laser treatment is not specific to the blood vessels but also damages the photoreceptors and other cells. However, the scar and loss of vision that result from this treatment may be mild in comparison to what would happen if the vascular network were allowed to advance unchecked. There are several types of lasers that can be used including Krypton, Argon (an inert gas) and dye. Deciding which one is used is left up to the eye practitioner, but it appears as though Krypton as well as dye lasers are best suited for work near the foveal region of the macula and that Krypton and Argon are both viable options in treating RPE detachments. Like any medical problem, early diagnosis of wet ARMD is imperative to obtain good results.
Currently under study, photochemical therapy is aimed at contesting the expansion of the vascular network common in cases of wet ARMD. This is accomplished by injecting the cancer drug BPD (benzoporphyrin derivative) in to the vessels of the diseased area. The drug is then exposed to laser light which destroys the cells responsible for vascularization. The amazing aspect is that it supposedly does not affect normal blood vessels in the retinal and choroidal regions, only the damaging vessels. Should this treatment evolve to fruition it could be the treatment of choice.
This is one of the many types of invasive therapies still in the research phase. The theory behind radiation treatment is that proliferating vascular cells (found in wet ARMD) are highly sensitive to low doses of radiation; whereas healthy retinal and vessel cells are relatively impervious. The treatment is generally given over the course of several days and may effect cells in nearby areas. Early results from many different sites across the country are encouraging but not definitive.
Strontium 90 is another form of radiation therapy. Instead of applying an external beam of radiation, a small applicator with Strontium 90 is inserted into eye near the developing vascular network. The benefit of this procedure, as opposed to external beam delivery, is that all of the radiation can be delivered at one time instead of over the course of several days. The reason behind this is that the radiation beam has to pass through several layers of the eye and its effectiveness is reduced by the time it reaches the target area. This problem is not met with the Strontium 90 technique because the radiation is so close to the area in question. Again, additional research must be performed regarding this possibly beneficial technique.
This form of therapy is very similar to radiation therapy in that both of them use a beam of radiation. The key difference between the two is that in proton therapy, the eye is radiated with a proton beam instead of an x-ray beam. This causes less damage to adjacent tissue and initial results show improvement and stability of vision. The drawback to this procedure should it prove beneficial, is that there are not many proton generators in the US. As a result, using one of these generators for eye procedures or even building more would be quite expensive. However, Indiana University is one of the few facilities where proton therapy for ARMD is being studied.
Low Vision Rehabilitation Therapy
Low Vision Rehabilitation (LVR) has aided countless ARMD patients. LVR is not a cure for ARMD, rather a way to help those with retinal damage lead more normal lives. This has been accomplished through a variety of avenues including: special lenses, optical devices, and electronic vision enhancers are a few. In addition, education has taught ARMD patients how to effectively use availabe vision. Many patients have been told nothing can be done when in fact low vision aids could be a great help.
The Disease |