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Background
Age-related macular degeneration (AMD) continues to be the leading cause of legal blindness in the USA. AMD is typically characterized by the presence of yellowish deposits of debris
(waste products) beneath the retina. These yellow spots are called drusen. Patients with large soft drusen are diagnosed as having nonexudative or "dry" AMD and have a 4-12%
chance per year of developing choroidal neovascularization (CNV), the most serious and sight-threatening complication of AMD. This condition, in which new blood vessels grow into the
back of the eye, is called exudative or "wet" AMD and is responsible for 90% of all AMD's serious vision losses.
The Macular Photocoagulation Study has proven the
benefit of laser treatment in some conditions of "wet" AMD. Unfortunately, the study results apply to less than 10% of all "wet" AMD cases and many eyes may still
not recover usable central vision. As of today, for all remaining "wet" AMD cases (the great majority), there are no proven cures. Clearly a prophylactic treatment that
could prevent the new blood vessels from developing in the first place would be highly desirable. The rationale for a prophylactic laser treatment of "dry" AMD is based on
the fact that laser treatment in patients with "dry" AMD has been shown to cause resorption (reduction in size or disappearance) of drusen, and this may benefit the natural
course of the disease. Remarkably, drusen resorption promoted by laser treatment occurs also in drusen not directly addressed by and distant from the laser treatment spots (e.g.
beneath the fovea, the center of vision) and the ophthalmic literature has reported some evidence that disappearance of drusen can, in some cases, lead to improvement of vision as
well as alter the natural rate of CNV occurrence.
Our PTAMD clinical trial utilizes a gentle "sub-threshold" diode laser treatment that minimizes damage to the retina
and is not perceptible to the patient nor to the clinician. This approach, tested in a pilot study, was reported safe and effective in reducing drusen and, in some cases, it improved
vision. It is the object and hope of the PTAMD clinical trial to confirm these results and to prove that this treatment can also decrease the development of CNV and the associated
severe visual loss.
If you have been diagnosed with "dry" AMD and would like to be considered for enrollment in the PTAMD clinical trial, please consult with your
ophthalmologist to find out if you meet the eligibility criteria.
Eligibility Criteria
If you have been diagnosed with dry AMD and would like to be considered for enrollment in the PTAMD Clinical Study please consult with
your ophthalmologist first to determine if you meet the eligibility requirements.
- 50 years of age or older.
- Willingness to be randomized and to participate in a 5 year study.
- "Dry" AMD with at least 5 large (³63µm) soft drusen in both eyes ("bilateral" arm of the study).
- "Wet" AMD in one eye and "dry" AMD with at least 5 large (³63µm) soft drusen in the fellow eye ("unilateral" arm of the study).
- Visual acuity of 20/63 or better on the ETDRS chart, in eligible eyes.
- Absence of geographic atrophy larger than 1 DD and closer than 1/2 DD from the center of foveal avascular zone.
- Absence of non-AMD related conditions that could limit vision, (i.e. optic neuropathy, significant corneal opacity,
dense cataract or significant diabetic maculopathy) and
of any disease, previous surgical procedure, use or potential need for toxic medications which may, now or in the future, complicate the evaluation of AMD.
Study Protocol
Bilateral patients
with both eyes eligible will have one eye randomized to laser treatment and the fellow eye assigned to observation.
Unilateral patients with only one eye eligible, will have
the eligible eye randomized to either laser treatment or observation.
Laser treatment consists of a grid of 48 "sub-threshold" (ophthalmoscopically invisible) diode
laser spots placed around the macula.
Typically, the procedure is completely painless. |
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