The purpose of this study is to determine the best dosing strategy when using Excimer Laser
to treat plaque-type psoriasis. In this study, half of the body's psoriasis will be treated
with a new dosing strategy, and the other half will be treated with the conventional method.
We hope to show that the new dosing strategy will result in faster improvement of psoriasis.
This is a randomized, assessor-blinded clinical trial to determine whether a novel
plaque-based dosimetry strategy can improve the speed of response to excimer laser treatment
in patients with plaque psoriasis. Each patient will receive plaque-based dosing on one side
of the body and conventional dosing on the contralateral side. This design is based on the
assumption that psoriasis usually affects patients in a symmetric distribution (e.g., knees
and elbows) and the effect of excimer laser phototherapy is limited to the treated plaque.
The side of the body treated with plaque-based dosimetry will be assigned using a table of
random numbers. The assessor will be blinded to the treatment group. Each patient will be
treated 1-2 times per week at the discretion of the investigator for a maximum of 10
1. Diagnosis of chronic plaque psoriasis for at least 6 months
2. Age ≥ 18 years
3. Body surface area affected ≤ 10 percent
4. Presence of at least one pair of bilateral target lesions with an area of at least 20
cm2 per target lesion. The bilateral target lesions must be present in the same
category of anatomical region (e.g., bilateral lower extremities, bilateral upper
extremities or bilateral trunk).
1. active or past history of erythrodermic psoriasis, guttate psoriasis, or pustular
2. history of photosensitivity disorder
3. history of malignant melanoma
4. active, invasive non-melanoma skin carcinoma
5. Fitzpatrick Skin Type I
6. Subject has received ultraviolet B phototherapy or any topical anti-psoriatic therapy
within two weeks prior to starting the study.
7. Subject has received systemic or topical psoralen-ultraviolet A photochemotherapy
within four weeks prior to starting the study.
8. Subject has received biologic therapy within three months of starting the study.