New England Eye Center - Advanced Eye Care

Visudyne Photodynamic Therapy (PDT)

Age-Related Macular Degeneration (AMD)

The vitreoretinal specialists at the New England Eye Center have extensive expertise in the management of age-related macular degeneration.

Figure 1Age-related macular degeneration (AMD) is a common eye condition that can cause significant visual loss in affected patients. The disease is divided into a dry form and a wet form.

The dry form generally causes gradual vision loss from deterioration of the retina. The wet form involves the growth of abnormal blood vessels under the retina called choroidal neovascularization (CNV); these blood vessels can leak fluid and blood and cause more rapid deterioration in vision. The diagram above illustrates the growth of these abnormal blood vessels under the retina in wet AMD.

AMD is the leading cause of severe, central visual loss in individuals over the age of 50. In the US, it is estimated that approximately 1.2% of our older population is affected by wet AMD, as opposed to 15.6% for dry AMD. However, approximately 90% of severe visual loss can be attributed to the wet form. Up to 200,000 new cases of wet AMD are diagnosed in the US each year.

Figure 2

Conventional Laser Photocoagulation

Treatments for wet AMD are aimed at destroying the new blood vessels to prevent further leakage and damage to the retina. This traditionally involved the use of a conventional laser. Laser therapy has been proven to benefit final visual outcome compared to no intervention at all. However, the conventional laser causes permanent scarring that damages the overlying retina when treating these abnormal blood vessels.

Figure 3The diagram to the left shows a laser beam aimed at abnormal blood vessels growing under the retina due to wet AMD. This therapy can effectively destroy the new blood vessels and control the disease process.

However, the diagram on the right shows the full effect of treatment. While the abnormal blood vessels were successfully destroyed, so too was the sensitive retinal tissue overlying the treated area.

Figure 4This patient would benefit from control of the leaking blood essels. However, they would also suffer vision loss due to retinal damage in the area treated by conventional laser. For this reason, better treatment options are desired when the center of vision is involved by growth of abnormal blood vessels in AMD. The goal is closure of the leaking blood vessels without immediate loss of central vision.

 

Visudyne Photodynamic Therapy

The vitreoretinal specialists at the New England Eye Center have extensive exPerience with this exciting, new treatment for wet age-related macular degeneration (AMD). Our retina service has been involved in the clinical research trials for this technique and has actually taught many of the specialists throughout the country how to perform the procedure.

Figure 5The current goal in the treatment of wet AMD is to close leaking new blood vessels without damaging the overlying retina. This is the precise value of photodynamic therapy (PDT).

The first step in the PDT procedure involves injection of a hoto-sensitizing agent (Visudyne) into an arm vein. This substance travels through the bloodstream and collects in the abnormal blood vessels under the retina.

Figure 6The retina is then treated with a low-energy laser to activate the photosensitizer. (This laser does not cause permanent scarring as in conventional laser treatment discussed above). A chemical reaction occurs, resulting in closure of the leaking blood vessels. There is no resulting damage to the overlying retinal tissue. Patients have a unique opportunity to preserve or even restore vision lost to wet AMD.

 

Figure 7The PDT procedure is performed in the office, very often on the same day the patient is first evaluated. The whole procedure is quick and painless. The photo-sensitizing drug is infused over 15 minutes, followed by an 83 second laser application.

Following the treatment, the patient must wear special eyeglasses and avoid direct sunlight for a few days. Other normal activities can be resumed immediately. Patients are followed regularly and are eligible for retreatment at 3-month intervals, should this be required.

Figure 8

Providing comprehensive evaluation and treatment of age-related macular degeneration throughout eastern Massachusetts.

Indications

  • Predominantly-classic choroidal neovascularization (>50% of lesion)
  • Subfoveal location

Benefits

  • Greater preservation or restoration of visual acuity compared to natural history
  • Closure of choroidal neovascular complex
  • No associated retinal damage