Light Treatment Effectiveness (LITE) Study

Open to people ages 12 years and up

1. Willing and able to provide informed consent (age 18+) or parental permission and assent (ages 12-17)
2. Age 12 or older
3. Plaque or guttate psoriasis predominantly located on trunk and/or extremities, with a physician global assessment average of >1.0, and considered a candidate for phototherapy
4. Patient is deemed willing and able to comply with either in-office or in-home phototherapy:
   1. In office: Able to travel about 3 times per week for 12 weeks from home, work and/or school during business hours of local site
   2. In home: Has space to accommodate home phototherapy unit and patient (or if 12-17, parent), willing and able to follow home phototherapy instructions
5. New or established patient in the practice

1. Patients who are judged unable or unwilling to comply with either in office or in home phototherapy due to time, work, school, or other financial constraints
2. Patients judged unable to follow home phototherapy protocol due to failure to demonstrate understanding of the following:
   1. How to operate the phototherapy device
   2. How to follow the dosing protocol
   3. Requirement to wear protective eyewear and genital protection equipment
3. Patients with known history of lack of efficacy to phototherapy or treated with phototherapy 14 days prior to baseline visit
4. Psoriasis predominantly located on scalp, body folds, genitals, palms and/or soles or with a physician global assessment average of ≤ 1.0
5. Patients deemed unsafe to be treated with phototherapy:
   1. History of photosensitivity or autoimmune disease such as lupus or dermatomyositis which can be aggravated by ultraviolet radiation
   2. History of arsenic intake
   3. Unable to tolerate standing for required duration of treatment due to age or physical function
   4. History of melanoma or multiple non-melanoma skin cancers that in the opinion of the principal investigator contraindicates treatment with phototherapy
6. Clinical site deems the participant is ineligible for reason other than eligibility or screening criteria.