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Photodynamic Therapy (PDT)
The term “photodynamic therapy” or PDT refers to the interaction of light with a drug (aminolevulinic acid or ALA) to achieve injury to targeted tissues that are pre-cancerous or unhealthy. The drug itself may be light sensitive or may be quickly converted by the body to a light-sensitive product, which is then activated by a special light source. Once activated, the drug produces a controlled injury to the damaged tissue but does not exert an effect on normal, healthy tissue.
PDT is used for both medical and cosmetic treatments to eliminate precancerous growths to treating difficult cases of acne.
Sun Damage and Precancerous Growths
For patients with extensive sun damage and a large number of precancerous growths, PDT is used for a medical benefit without particular attention to cosmetic improvement. When the primary treatment goal is elimination of precancerous areas, a special blue light is used to activate the ALA. Blue light is used as this energy is more effective than any other at stimulating the PDT process. PDT can be used to treat the face, scalp, neck, chest, hands, arms and other areas.
Cosmetic Improvement of Skin
PDT can be used to improve the appearance of sun damaged skin. When this endpoint is our goal, we often activate the ALA using a blue light in conjunction with either intense pulsed light (IPL) or pulsed dye laser (VBeam). Combining these treatments helps achieve improvement in skin quality and reduce brown discoloration and redness that is often associated with sun damage.
PDT treatments are also useful in the treatment of acne. The ALA is actively absorbed by the oil-producing glands that cause blemishes and kills the bacteria than can cause acne breakouts. Traditional treatments such as Retin-A and other similar drugs, topical and systemic antibiotics, and in some situations hormonal therapy should remain the first line treatment for acne; however, for those individuals whose acne is resistant to the standard therapies or who are unable to be fully compliant with the sometimes complex regimens required, PDT can be an excellent alternative. Patients undergoing PDT treatment for acne typically require three sessions spaced 2-4 weeks apart.
What to Expect during a PDT Treatment
- Microdermabrasion: Prior to beginning the PDT treatment, the area to be treated is prepared using the Vibraderm microdermabrasion device. This device gently polishes the skin, removing the dead cells that collect on the surface thereby enhancing penetration of ALA into the skin.
- ALA Application: The ALA is a clear solution that is applied quickly and without discomfort.
- Resting Period: A variable amount of time, typically from 30 to 90 minutes, will be allowed to elapse while the ALA is absorbed into the target area and chemically converted to a light-sensitive agent. During this time you can relax quietly and comfortably. Exposure to the blue light typically requires an additional 10-20 minutes.
- Cleansing and Moisturizing: At the conclusion of this process the skin is gently cleansed and moisturizer and sunblock are applied. It is imperative that sun exposure be avoided for approximately 36 hours after application of the ALA as this can result in an exuberant response.
What to Expect after a PDT Treatment
The typical post treatment period after ALA-PDT involves a varying degree of redness, swelling and peeling that is similar to sunburn. During this time most patients liberally apply moisturizer and sunblock. Some patients experience very little reaction, while other patients can have a more exuberant response. Those patients who have a dramatic reaction to the PDT treatment usually find that liberal application of Aquaphor Healing Ointment for several days keeps their skin moist and comfortable. The vast majority of patients find that their skin is back to normal approximately one week after treatment. Depending on the amount of sun damage present and the degree of reaction to the first PDT treatment, a second treatment session may be recommended 1-2 months after the first. Any abnormal appearing areas that persist despite PDT treatment will require either biopsy, treatment with topical agents such as Aldara, Carac ,Efudex, Picato, or surgical excision.
Intense Pulsed Light Combined with Photodynamic Therapy (IPL-PDT)
IPL treatments are well known to improve the appearance of sun damaged skin by reducing brown and red discoloration. Four to six treatments are typically required to achieve best outcomes. However, with the use of ALA, the number of treatments required to achieve best outcomes with IPL can be reduced as much is 50%. As is true with all laser and light based treatments, treatment should not be performed on patients who have any active infections in the treatment area or who are tanned in the treatment area.
Is PDT Treatment covered by Health Care Insurance?
In some situations, a portion of the costs of PDT therapy may be covered by insurance. However, in most scenarios at least some out-of-pocket expense should be anticipated.
Results from PDT Research
In a study submitted to the Food and Drug Administration (FDA) for approval of ALA in the United States, 243 patients with numerous precancerous areas on the face underwent treatment with ALA followed by activation with a special blue light.
- Nearly 80% of the precancerous growths were cleared by one treatment
- Approximately 10% more resolved with a second session
- 94% of patients noted improvement in the appearance of their skin following PDT treatment