MANAGING PATIENTS WITH AMD
This section covers some point on managing patients with AMD, including:
- Laser photocoagulation
- Photodynamic therapy (PDT)
- Anti-angiogenesis Therapies
- Angiostatic Therapies
- Combination Therapies
- Vision rehabilitation
- Monitoring
- Useful field of vision
- Measures to minimize loss of vision
Laser photocoagulation
Laser photocoagulation is an outpatient surgical procedure whereby laser energy is applied to the retina to seal leaking blood vessels and reduce growth of these blood vessels.
The Macular Photocoagulation Study (MPS) Group showed that laser photocoagulation is effective in the treatment of well-defined extrafoveal or juxtafoveal choroidal neovascularisation, CNV, and for small, well-defined subfoveal lesions with evidence of classic CNV.
Vision often does not improve after treatment and may even deteriorate; in general, treated patients lose less vision than untreated patients.
In the MPS clinical trials some lesions showed a high rate of recurrence and a risk of spontaneous progressive enlargement of the atrophic photocoagulation scar leading to worsening of visual acuity.
Laser photocoagulation is currently recommended for the treatment of well-demarcated extrafoveal lesions, and for juxtafoveal lesions that are sufficiently removed from the fovea so that treatment would not extend under the center of the foveal avascular zone.
Photodynamic therapy (PDT)
PDT is a two-step outpatient procedure involving the intravenous administration of a photosensitizing drug (e.g. VisudyneŽ), followed by irradiation by a non-thermal laser to activate the photosensitizer drug molecules.
Free radicals and singlet oxygen molecules are produced, resulting in disruption of cellular structures and, ultimately, vessel thrombosis and vascular occlusion.
Visudyne treatment is administered as a multicourse therapy based on patient's eligibility.
Visudyne therapy is the first pharmacologic treatment shown to have long-term safety and efficacy for many patients with subfoveal wet AMD in randomized clinical trials. It has been approved by the FDA for treatment of AMD patients with predominantly classic subfoveal CNV and is also approved for the treatment of occult with no classic CNV in the European Union and many other countries outside the US.
The TAP Investigation showed that patients with this type of AMD who were treated with Visudyne therapy lost less visual acuity and contrast sensitivity after 2 years than patients given placebo.
As with laser photocoagulation, vision often does not improve after treatment with PDT and may even deteriorate; in general, treated patients lose less vision than untreated patients.
Anti-angiogenesis Therapies
As of February 2006, pegaptanib sodium (trade name Macugen) is approved for use in Canada, the United States and Europe. The United States Food and Drug Administration (FDA) approved Macugen for treatment of neovascular (wet) age-related macular degeneration. FDA approval came following successful clinical trials demonstrating that the drug reduced vision loss in 70 per cent of clinical trial patients. It is also very encouraging that the drug is effective for all kinds of wet AMD, whether in the early or late stages.
Pegaptanib sodium (trade name Macugen) is what researchers call an anti-VEGF drug, or in other words, a drug which works by targeting the proteins which act to trigger abnormal blood vessel growth and leakage. Anti-VEGF drugs are delivered directly to the eye by an injection, which is repeated every four to six weeks.
Other anti-VEFG drugs on the horizon include ranubizimab (trade name Lucentis), from Genetech and Novartis. On June 30, 2006, the US Food and Drug Administration (FDA) announced approval of Lucentis (Ranibizumab). AMD Alliance International (AMDAI) loudly applauded the decision, which effectively makes available in the USA a ground breaking treatment for wet age related macular degeneration. This approval is based on the evidence presented from several years of rigorous clinical trials, in which Lucentis was shown to maintain vision in 95% of trial participants, and improve vision in approximately 30 to 40% of trial participants. This decision means that treatment with Lucentis will now be widely available in the USA through retinal specialists. The FDA approval of course only covers the USA.
On August 29, 2006 Switzerland became the first European county to approve Lucentis as a treatment for wet AMD. Introduction of Lucentis in other countries is expected to follow in the coming year. AMD Alliance International applauds the introduction of new treatments, which bring hope and help to those with macular degeneration.
Angiostatic Therapies
In other research developments, a completely different class of AMD drugs, called angiostatic therapies, is showing promise. This class of drugs propose yet another approach to treatment of AMD, in this case by administering a type of steroid to stop the abnormal growth of blood vessels in the eye. Unlike the anti-VEGF treatments, angiostatic drugs are delivered through a canula, to the back of the eye.
One possible angiostatic treatment is anecortave acetate (Retaane), from Alcon Laboratories. Although early clinical results were not as stellar as hoped, scientists working on the treatment believe this may be a result of drug delivery problems, not the drug itself and are making adjustments. On May 24, 2005, the USA Food and Drug Administration released what is called an "approvable" letter, basically meaning that the drug is approvable but some further study is required. Alcon recently reported that their researchers and officials will "meet with the FDA to discuss the approvable letter, the clinical studies submitted with the NDA and other ongoing clinical studies for RETAANE suspension to determine the steps necessary to gain final approval for the wet AMD indication." Retaane has received market approval for use in Australia. In early March 2006, a request for market approval in Europe was withdrawn, by Alcon, from regulatory consideration.
Combination Therapies
Other investigations are also showing promise, including combination therapies, which combine traditional PDT therapy with new drugs to increase the effectiveness of PDT. Combination treatments pair one or more existing or new AMD treatments to see if the end result might be greater than what could be achieved individually. More and more medical practitioners believe that combination methods are the way of the future for wet AMD treatment. Usually the idea is that one kind of treatment will take care of existing AMD in the patient, and the other will help to prevent any future developments.
Vision rehabilitation
Research by Lighthouse International in 1995 showed that 94% of adults reporting vision problems did not take advantage of any vision rehabilitation services.
Studies have shown that referral to low vision or psychological/psychiatric services, or to vision rehabilitation services, occupational therapy or support groups may improve patient functional status and quality of life. It is preferable to refer patients early in disease progression so that relationships and skills are developed.
Low vision rehabilitation services include prescription of low vision optical and non-optical devices, absorptive lenses, and electronic assistive devices, as well as training in independent and safe travel and modifying the home and work environment.
Certified vision rehabilitation teachers train patients in new ways to accomplish everyday tasks and alternative methods for navigating safely while moving through their everyday lives, thereby increasing patient satisfaction and quality of life.
Monitoring
Monitoring patients with AMD is important. Eligible lesions should be considered for treatment when they are first observed; lesions need to be monitored regularly because disease progression may result in growth of lesions or conversion from treatable to untreatable lesions or from untreatable to treatable lesions.In addition, treating ophthalmologists can play a key role in referring appropriate patients for low vision rehabilitation services, psychological services, etc. and in this way impact a patient's quality of life.
Useful field of vision
Patients can be taught eccentric viewing techniques to compensate for central scotomas.
Knowledge of the scotoma position relative to fixation can help in predicting difficulties faced, for example in returning to the left hand margin on a page when reading (scotoma to the left of the PRL) or hand-eye coordination (large central scotoma).
Additional magnification or illumination can also be useful for certain patients.
Measure to minimize loss of vision
Patients can monitor the health of their eyes and help to minimize visual loss by:
- scheduling routine eye examinations
- eating dark green leafy and orange vegetables
- protecting eyes from the sun
- not smoking
- controlling blood pressure and serum cholesterol levels
If strictly applied over several years, vitamin supplements could reduce the visual loss of over 250,000 Americans who are at high risk of developing advanced AMD.The Age-Related Eye Disease Study (AREDS) has found that selected patients with AMD treated with high doses of antioxidants and zinc have a 27% lower relative risk at 5 years of developing advanced AMD and moderate visual loss compared with a placebo group.
