• The primary efficacy endpoint is "Treatment Success," a static endpoint defined as a score of 0 to 1 at Day 28 (at the end of the study treatment period) by the Investigator's Global Assessment (IGA) scoring system for atopic dermatitis status. [ Time Frame: 28 days ] [ Designated as safety issue: No ]
• Adverse experience, including pain and dermatologic/skin toxicity (incidence, severity, frequency, duration and causality). [ Time Frame: 8 weeks ] [ Designated as safety issue: Yes ]

• Investigator's Global Assessment (IGA) score changes at each visit from Day 1 pre-treatment. [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
• Eczema Area Severity Index (EASI) score changes of individual atopic dermatitis signs at each visit from Day 1 pre-treatment. [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
• Pruritus Self-Assessment score changes of atopic dermatitis related itching/scratching at each visit from Day 1 pre-treatment. [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
• Adverse change in clinical laboratory tests (CBC and CMP). [ Time Frame: 8 weeks ] [ Designated as safety issue: Yes ]
• Adverse change in vital signs (BP, pulse, temperature). [ Time Frame: 8 weeks ] [ Designated as safety issue: Yes ]

PH-10 is a formulation of rose bengal disodium (RB) for topical administration to the skin. PH-10 is capable of undergoing photochemical reactions when activated by ambient light. This phase 2 study will assess whether topical PH-10 applied once daily to mild, moderate or severe areas of atopic dermatitis (including atopic eczema) may ameliorate inflammation of the skin when activated by ambient light.

Inclusion Criteria:

• Men or women, age 18 or older.
• Mild, moderate or severe atopic dermatitis.
• Presence of atopic dermatitis areas outside the head and face with a baseline Investigator Global Assessment (IGA) of 2 (mild disease), 3 (moderate) or 4 (severe disease) at screening.
• Written informed consent by the subject or legal guardian.

Exclusion Criteria:

• Women who are pregnant, attempting to conceive, or nursing an infant.
• Subjects who have received phototherapy (UVB, PUVA) or systemic therapy (immunosuppressants, cytostatics, corticosteroids) within 4 weeks.
• Subjects who have received systemic antibiotics within 2 weeks.
• Subjects who have received topical therapy (tar, corticosteroids) within 7 days.
• Subjects who have received investigational drugs in a clinical research study within 4 weeks.
• Subjects who have received agents posing a clinically significant risk of photosensitivity reaction within 5 half-lives of initiation of study treatment.
• Subjects with a history of porphyria, systemic lupus erythematosus or xeroderma pigmentosum.
• Subjects with clinical conditions that may pose a health risk to the subject by being involved in the study or detrimentally affect regular follow-up of the subject.