Efficacy and Safety Study With Visonac Photodynamic Therapy (PDT)

Inclusion Criteria: * Female and male patients, above 9 years of age with moderate to severe facial acne vulgaris (IGA score 3-4). * Female patients who are surgically sterile, pre-menstrual, postmenopausal, abstinent, or willing to use an adequate means of contraception including birth control pills, or barrier methods and spermicide for at least 14 days prior to T1. Patients using birth control pills must have used the same product and dose for at least 6 months and must agree to stay with the same product and dose for an additional 6 months. * Fitzpatrick skin type I through VI. * Patients with 20 to 100 inflammatory lesions (papules, pustules, and nodules) on the face. * Patients with 30 to 120 non-inflammatory lesions (open and closed comedones) on the face. * Patients with no more than 2 nodular lesions on the face. * Signed and verified informed consent form. For subjects under age of 18, an assent form in conjunction with an informed consent form, signed and verified by parent/guardian. Exclusion Criteria: Patients presenting with any of the following will not be included in the study: * Patient is the investigator or any sub investigator, research assistant, pharmacist, study coordinator, other staff or relative thereof directly involved in the conduct of the protocol. * Patients unlikely to comply with the protocol, e.g., mental condition rendering the patient unable to understand the nature, scope, and possible consequences of the clinical study, uncooperative attitude or unlikelihood of completing the study (e.g., drug or alcohol abuse). * Female patients using oral contraceptives, that have not used the same product or dose within the last 6 months and do not agree to stay with the same product and dose for the duration of the study. * Pregnancy * Patients undergoing testosterone or any other systemic hormonal treatment. * Patients using hormonal contraceptives solely for the control of acne. * Known allergy to MAL, to a similar PDT compound, or to excipients of the cream. * Patients with porphyria. * Patients with cutaneous photosensitivity. * Participation in other clinical studies either concurrently or within the last 30 days, before T1. * Patients with a washout period for topical treatments e.g., topical BPOs, retinoids and antibiotics, for their acne of less than 14 days, before T1. Medicated cleansers may be used during the washout period and stopped before the treatment. * Patients with a washout period for oral antibiotics for treatment of their acne of less than 1 month, before T1. * Patients with a washout period for oral isotretinoin of less than 6 months, before T1. * Patients with a beard or other facial hair that might interfere with study assessments. * Patients with melanoma or dysplastic nevi in the treatment area. * Exposure to ultraviolet radiation (UVB phototherapy, sun tanning salons) within the last 30 days. * Exposure to PDT within 12 weeks before T1.