Patients will be screened up to 28 days before start of treatment. During the screening visit, the purpose and procedures of the study will be explained to potential patients and informed consent will be obtained.

At the baseline visit, all inclusion and exclusion criteria will be re-assessed. Eligible patients will be randomized to treatment of the target area with either 30 minutes (group30) or 15 minutes (group15) blue light at 600 milliwatt per square centimeter (mW/cm²). Additionally, two study areas with similar clinical symptomatology will be determined and will be randomized to blue light treated area and Daivonex (Vitamin D) treated area.

After randomization, patients will be trained on a demonstrator device (no actual treatment to ensure investigator is blinded as to which group the patient is randomized to) as well as the Daivonex cream. After patients have been instructed, treatment of the areas will be applied daily (once per day, 5-7 times / week) at home for a treatment period of 12 weeks. During those 12 weeks, patients will return to the study site for safety and effectiveness assessments at week 2, 4, 8 and week 12. A phone call visit will be performed after one week of treatment to check for any adverse events or problems in handling the device or the cream. The visit at week 12 serves as end of treatment visit. The patients will be followed-up for another 4 weeks. Treatment responses will be photo documented.

Inclusion Criteria:

1. Signed and dated informed consent prior to any study-mandated procedure

2. Good health as determined by the Investigator

3. Willing and able to comply with study requirements

4. Skin type I-IV according to Fitzpatrick

5. Mild plaque-type psoriasis vulgaris with a Psoriasis Area and Severity Index (PASI) ≤ 10 and body surface area (BSA) ≤ 10 at screening.

6. Presence of two comparable psoriatic plaques suitable to be defined as study areas as follows:

   • located on extremities (plaques located on the palms or sole of the feet are not suitable)
   • Both areas located either on lower or upper extremity
   • Can be located on the same extremity
   • Distance between the two study areas ≥ 11cm (border to border)
   • If lesion is too large to be fully covered, partial treatment possible

7. Otherwise healthy according to physical examination

8. Aged 18 years up to ≤74 years

9. Reliable method of contraception for women of childbearing potential (i.e. low failure rate less than 1per cent per year; e.g. oral contraceptives, intra-uterine device (IUD) or transdermal contraceptive patch)

10. Willing to abstain from excessive sun / UV exposure (e.g. sunbath, solarium) during the course of the study

Exclusion Criteria:

General

1. Inmates of psychiatric wards, prisons, or other state institutions

2. Investigator or any other team member involved directly or indirectly in the conduct of the clinical study

3. Participation in another clinical trial within the last 30 days

4. Pregnant or lactating women Medical History

5. Photodermatosis and/or Photosensitivity

6. Porphyria and/or hypersensitivity to porphyrins

7. Patients with current diagnosis of erythrodermic, exfoliative or pustular psoriasis

8. Congenital or acquired immunodeficiency

9. Patients with any of the following conditions present on the study areas: naevi or signs of hyperpigmentation, viral (e.g. herpes or varicella) lesions of the skin, fungal and bacterial skin infections, parasitic infections and atrophic skin

10. Patients with any of the following conditions present or who have been diagnosed in the past with any of the following conditions on the study areas: skin cancer, severe actinic damage and other precancerous lesions

11. Patients with genetic deficiencies attached with increased sensitivity to light or increased risk to dermatologic cancer ( i.e. Xeroderma pigmentosum, Cockayne Syndrome, Bloom-Syndrome) Concomitant medication/treatment in medical history and during the study Required

    • Treatment of target and control area with Excipial U10 Lipolotio (Galderma)
    • Treatment of control area with Daivonex (Leo Pharma) Allowed
    • Topical treatment of non-study areas with Vitamin D or WHO group I-II corticosteroids or mometasone Not allowed Within 3 months prior to baseline
    • ustekinumab Within 2 months prior to baseline
    • adalimumab, alefacept, infliximab Within 1 month prior to baseline
    • Etanercept
    • Systemic corticosteroids
    • Retinoids
    • Immunosuppressants (e.g. methotrexate, ciclosporin, azathioprine, chemotherapeutics)
    • oral psoralen with ultraviolet A (PUVA)
    • Topical or intranasal/inhalation therapy with potent or very potent (WHO group III-IV) corticosteroids

Within 2 weeks prior to baseline

• ultraviolet B light (UVB) / ultraviolet A light (UVA)

• Topical therapy with

• WHO group I-II corticosteroids

• Topical retinoids

• Vitamin D analogues

• Topical immunomodulators (e.g. calcineurin inhibitors)

• Anthracen derivatives

• Tar

• Salicylic acid

• Intranasal/inhalation therapy with WHO group I-II corticosteroids At baseline

  • Photo-sensitizing medication (e.g. psoralen, tetracycline, nalidixic acid, furosemide, amiodarone, phenotiacine, chinclone, fibrates, hypericumperforatum, arnica, valerian, tar, psoralen, ketoprofen) or colours (e.g. thiazide, toluidine blue, eosin, methylene blue, rose Bengal, acridine)
  • Initiation of, or expected changes in concomitant medication that may affect psoriasis vulgaris (e.g., beta blockers, anti-malaria drugs, lithium and angiotensin converting enzyme (ACE) inhibitors)

Adverse events were collected during the complete 16 weeks of the clinical Investigation.

Any untoward medical occurrence, unintended disease or injury, or any untoward clinical signs (including an abnormal laboratory finding) in patients, users or other persons whether or not related to the investigational medical device. This includes events related to the investigational device or the comparator. This includes events related to the procedures involved. For users or other persons this is restricted to events related to the investigational medical device.