Inclusion Criteria:  Male and females 18 - 75 years of age inclusive Patients with DLSO of at least one great toe Patients with DLSO in the target toe confirmed by positive KOH and positive fungal culture for dermatophytes Willingness to abstain from pedicures, nail clipping, or application of nail polish or nail cosmetics to their toenails over the study period  Exclusion Criteria:  History of any significant chronic fungal disease other than onychomycosis or an immunocompromised condition Any previous surgery to or abnormalities of the target toe that in the investigator's opinion could prevent the toenail surface area from clearing even if eradication of the DLSO infection is achieved Participation in another clinical study of an investigational drug or device within 3 months of screening No administration of oral terbinafine or another oral antifungal within 6 months of screening No topical antifungal used for onychomycosis or a dermatophyte infection (i.e. tinea pedis) within 3 months of screening No uncontrolled diabetes mellitus No severe psoriasis or severe atopic dermatitis  Other protocol-defined inclusion/exclusion criteria may apply