Thirty studies of variable quality were included.
Eight trials showed that topical tretinoin cream, in concentrations of 0.02% or higher, was superior to placebo for participants with mild to severe photodamage on the face and forearms (although losses to follow up were relatively high in most studies). For example, the relative risk of improvement for 0.05% tretinoin cream, compared to placebo (3 studies), at 24 weeks, was 1.73 (95% confidence interval 1.39 to 2.14). This effect was not seen for 0.001% topical tretinoin (1 study) or 0.01% (3 studies). A dose-response relationship was evident for both effectiveness and skin irritation.
One small within-patient study showed benefit from topical ascorbic acid compared with placebo.
Tazarotene (0.01% to 0.1%) and isotretinoin (0.1%) both showed significant improvement over placebo for moderate photodamage (one study each).
There is limited evidence (one trial), to show that the effectiveness of 0.05% tretinoin, is equivalent to the effects of 0.05% and 0.1% tazarotene.
One small study showed greater improvement in upper lip wrinkles with CO2 laser technique compared to Baker's phenol chemical peel, at six months.
Three small RCTs comparing CO2 laser with dermabrasion found no difference in wrinkle score at four to six months, suggesting that both methods are equally efficacious, but more erythema was reported with the laser.
The effectiveness of other interventions such as hydroxy acids and natural polysaccharides was not clear.
