Even though the propagated superiority of picoseconds over nanosecond lasers is still controversially discussed due to the inconsistent data situation, there is now an increasing number of controlled studies and reviews that demonstrate the one, albeit partly limited, superiority of picosecond systems. A recent review by Wu and colleagues evaluates all possible indications for picolasers and quantifies evidence levels according to the currently available study results. Benign pigment lesions receive an evidence level of I-IV, tattoos the highest level I. The authors therefore call picolasers the current gold standard for the removal of tattoos of almost any color [1].

This is consistent with the results of a new prospective clinical study that demonstrates the superiority of 532 nm and 1064 nm picosecond lasers over corresponding nanosecond lasers for the removal of various tattoo colors [2].

Picolaser pulses of the wavelength 1064 nm proved to be significantly more effective for the removal of black tattoos than all other examined wavelengths and pulse durations; at the same time, 532 nm picolaser pulses proved to be most effective for the removal of all other examined tattoo colors (here: red and green).

A recent review by Mehrabi et al. lists as “non-tattoo indications” for picolaser pigment lesions ranging from lentigines and cafe au lait stains, nevus ota, postinflammatory hyperpigmentation, periorbital darkening and melasma, to hyperpigmented scars [3]). An interesting option for more effective removal of light lentigines is a pretreatment with biophotonic fluorescence energy. This not only stimulates wound healing processes, a transient light hyperpigmentation also darkens existing lentigines and unmasks subclinical lesions. This makes the entire treatment more effective and safer [4].

The use of picosecond lasers also appears promising outside the treatment of pigments. Possible indications range from epidermal nevi and striae to atrophic (acne) scars and rejuvenation [4]. The reaction of the picosecond laser impulse with melanin particles in the skin results in laser-induced optical breakdown (LIOB) and consecutive laser-induced cavitation (LIC); microscopic defects in the skin are thus set, which are supposed to stimulate collagen and elastinneogenesis (e.g. [5]). A recent randomized, blinded split-face study demonstrated a significant improvement in acne scars and associated post-inflammatory erythema after three treatments with a 755 nm alexandrite picosecond laser [6].

A relevant number of studies have also been published on the therapeutic principle of LADD, i.e. the use of ablative fractional laser systems and the reduction of the epidermal barrier function of the skin, thus increasing the bioavailability of topically applied active ingredients. Banzhaf et al. report on the successful treatment of nodular and superficial multicenter basal cell carcinomas using CO₂-LADD of ingenolmebutate [7]. According to a recent study, the cutaneous bioavailability of the chemotherapeutic agent cisplatin can also be increased by LADD and could thus offer an option for the treatment of superficial and deep-seated skin tumors [8]. The same group demonstrated in a proof-of-concept study of 20 patients with uncomplicated basal cell carcinoma that such tumors can indeed be effectively treated with the CO₂-LADD of cisplatin in combination with 5-FU [9]. In a recent retrospective study of vitiligo treatment, 40.3 percent of the 1,026 lesions treated with a combination of a fractional Erb:YAG laser and topical betamethasone responded over a 12-month observation period [10]. In androgenetic alopecia, pretreatment with the fractional CO₂ laser also increases the effectiveness of topically applied minoxidil [11].

According to a recent international consensus paper, lasers are the first choice in the treatment of traumatic scars and contractures. The application includes different wavelengths and emission types and ranges from the treatment of erythema and vessels using vascular lasers, through ablative and non-ablative fractional laser therapy, to LADD of triamcinolone and/or 5-FU [12].

A recent review of onychomycosis suggests that non-ablative laser therapy has a cure rate in the range of 10 to 15 percent [13]. However, the strategy of LADD of antimycotics has not yet been included here. Indeed, in a recent study, CO₂ laser-assisted application of an antifungal cream with a healing rate of 25% after 24 weeks proved to be significantly more effective than the application of the cream without laser (3.75% healing) [14].

A fractional CO₂ laser also proved to be effective in treating the pruritus of primary cutaneous amiloidosis. Interestingly, the authors were able to demonstrate the reduction of the itching mediator IL31 and its receptor in treated lesions – an exciting new basic science association for laser treatment [15].

Remarkably, according to a recent meta-analysis, not lasers but topical bleaching externals (hydroquinone, possibly also in combination with retinoids and glucocorticosteroids) are still the treatment of choice for melasma. Chemical peelings or lasers are at best the same, rather less effective and with significantly less favorable side effect profiles. Systemic tranexamic acid appears promising. However, there are still no well-controlled studies [16].

Finally, a current metanalytic analysis summarizes the literature on the question of isotretinoin administration and the safety of laser treatments under this therapy. The authors conclude that systemic isotretinoin does not or only slightly increase the risk of side effects of laser treatment [17].

In summary, many exciting developments in the field of medical laser therapy are emerging even in times of the corona pandemic. The field is increasingly consolidating its importance as an essential component of modern, aesthetic dermatological practice.