Field change refers to areas of skin that have multiple AK associated with a background of erythema, telangiectasia and other changes seen in sun-damaged skin. These areas are probably more at risk of developing squamous cell carcinoma (SCC), especially if left untreated and, as such, it is recommended that they should be treated more vigorously. As such, the treatments should be applied to the whole area of field change and not just the individual lesions.