Phototherapy is the use of light as therapy in skin diseases. Excimer laser and pulsed light is a new generation phototherapy modality that concentrates one type of light (ultraviolet B) at a specific wavelength (308 nm) to treat several types of skin diseases. UVB has anti-inflammatory properties and it is used for the treatment of skin diseases such as psoriasis, vitiligo, and eczema, among others.
Excimer laser and pulsed light system allows for a concentrated beam of UVB to be directed solely to the diseased area for maximal benefit and least possible side effects to normal skin. Classically, vitiligo and psoriasis have been treated with the excimer laser. Other cutaneous conditions that also respond to Excimer include: alopecia areata, mycosis fungoides, lichen planus and eczema.
The session is usually short, not exceeding 15 minutes. On your first visit, your dermatologist will start by asking a few questions to make sure that you do not have a contraindication to phototherapy.
A test will be done on the inner aspect of your forearm to determine your minimal erythemal dose (MED), which is the dose at which you start to get some redness. This test should be read after 24 hours and it will allow your dermatologist to set your first dose.
Depending on the skin condition that is treated, your dermatologist will then proceed to treat the areas that are affected on the same day or on a subsequent visit after obtaining your MED. The procedure is not painful. You will feel some heat but no pain.
You may need between 15 and 30 sessions depending on the skin problem that we are treating:
- For psoriasis: Large studies have shown that around 80% of patients reach an improvement of 75% or better after 10 or fewer treatments and 50% of patients reach an improvement of 90% or better after 10 or fewer treatments. Patients usually show significant improvement within 6 sessions. Some patients may require maintenance treatment for a given period after complete improvement.
- For vitiligo: The number of sessions depends on the location of the vitiligo and the duration of the disease. For example patients who have vitiligo on the face respond better and faster than patients who have it on the fingers. Also if the patches are new, the respond faster than older patches. Usually patients achieve a 75% repigmentation within 12 sessions. In vitiligo, maintenance treatment is important after achieving the desired result.
It is important to apply a sunscreen with an SPF of 30 or more on the treated area and to avoid sunbathing and prolonged exposure to sunlight on the same day as the treatment. This is a treatment that can be done in summer and in the winter if proper precautions are taken.
It is recommended to avoid all topical products for 4 hours EXCEPT mineral oil, which allows for the laser beam to penetrate better, especially over the elbows and knees.
Excimer is a safe modality of treatment that has been used for over 15 years. Some patients may experience side effects that resemble a sunburn such as redness, itching and rarely a blister. It is important for you to inform your dermatologist of these changes so that they can adapt the dose of UVB on your next session.
It is possible with any form of UV light that an increased incidence of skin cancer may occur later in some patients, usually only with many UV light treatments over extended areas of skin. The targeted nature of 308-nm UVB laser phototherapy, short treatment time, and the low number of treatments may reduce this risk.
Although this is a safe technology, there are several contraindications to treatment with excimer including:
- Having a personal history of skin cancer
- Having a family history of melanoma
- Having a photosensitive disease, meaning a disease that gets worse with sunlight. (this will be determined by your physician at the first visit)
- Taking photosensitizing medications (as determined by your physician at the first visit)