A Great Advance in Preventing Damage from Macular Degeneration

For at least 20 years the only therapy proved useful against age related macular degeneration (ARMD) was coagulation of wet ARMD by laser beam.  A burning light from the ruby laser was focused directly on the spots under the macula where hemorrhage was damaging central vision.  The laser beam stopped the bleeding the way a plumber's iron plugs leaky pipes.

Every time the laser burned a leak it created a tiny blind spot.  Also the scars with which nature had attempted to stop the hemorrhage accumulated.  Together the spots and scars diminished central vision.  Thus, treatment was only temporarily and partially helpful, since the damage inflicted by doctors and by nature was irreversible.

The bleeding is the result of the unchecked proliferation of unneeded blood vessels beneath the macula, which is known as neovascularization.  These blood vessels are not only useless; they are dangerous because they are fragile, break, causing scarring.  The scars block the macula from creating sharp central vision.  Neovascularization is a serious part of several dangerous diseases, including cancer.

Researchers in these various pathologies have been looking for some way of controlling them.  Many modalities have been tried, including chemotherapy, the laser and other forms of light.  For at least two decades experimental treatment of cancer of the bladder has applied nonburning light as a tool.

A Canadian laboratory discovered a compound that sensitizes tissues to the biological power of cold light.  The possibility arose that this could perhaps be used in place of the burning laser to treat macular degeneration.  The chemical, known as Visudyne, has an affinity for newly growing blood vessels.  It seeks out and binds to cholesterol-like particles known as low density lipoproteins (LDL) in the walls of these vessels.  There is more of this fatty substance in growing vessels.

In a process known as photodynamic therapy, injecting a patient with Visudyne, waiting until it reaches the target area under the macula, then hitting it with a cold laser light causes oxidation of the fast growing cells.  This creates blood clots and the vessels become nonfunctional.

The result parallels that of the burning laser, but minus the blind scars.  However, the body continues to grow more useless vessels, so PDT (photodynamic therapy) has to be repeated at least every three months.  Repetition is wasteful and the process is not entirely without damage to normal retinal cells.  PDT does not improve vision but stabilizes it.

"Frequent repetition is a high price for PDT treatment," says research ophthalmologist Richard M. Spaide, M.D.  "If you look at macular degeneration under a microscope, you see a lot of white cells.  This indicates that part of the disease if inflammatory.  The way to treat that is with steroids such as cortisone.

"Visudyne also has a bad side.  Not only does it plug the unwanted blood vessels but it also has the reverse tendency of stimulating growth of these vessels.  And corticoid steroids not only fight inflammation but actually also act against vessel growth."

Knowing these facts, Dr. Spaide made the brilliant decision to combine Visudyne and Triamcinolone (cortisone).  He did this by first using the photodynamic therapy and then injecting cortisone directly into the eye.  Tried in 50 patients, the combined therapy not only prolonged the Visudyne protection but also substantially reduced unwanted secondary effects.

The two-step therapy prolonged duration of the anti-vascular effect as against the damage of the former one-step treatment.  Patients injected with cortisone more than doubled the period between treatments.  Cortisone also, as noted, protects against the side effects of Visudyne.  Result:  Unlike one-step patients who suffered some reduction in sight, the two-step subjects improved their vision by an average of two lines on the eye chart.

These results have encouraged a larger trial among 60 macular patients.  Subjects are currently being recruited at eye centers in New York City, Philadelphia, Chicago and Cleveland.

Study subjects will be limited to patients in the early stages of ARMD.  Dr. Spaide sympathizes with those of us whose disease has advanced.  "The reason," he says, "is that macular degeneration is like a house fire.  If you put it out before it has burned too much, you may save the structure, but if it burns too long, you have only ashes.  Nothing left.  That is why we can't surgically remove the scars in the eye.  The macula has been destroyed.  The scar is all that's left."

Both one-step PDT (using PDT by itself) and two-step PDT (using PDT with Triamcinolone) do not interfere with 95% of sight, which is peripheral vision.  This ability is sustained regardless of ARMD and continues as long as the rest of the eye remains healthy.

This article is reprinted with permission from the newsletter Eyes Only, a publication of the Association for Macular Diseases, Inc.,

210 East 64^th Street, New York, New York 10021, 212-605-3719.

(Autumn 2003 - Winter 2004 issue)

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