Portal de Periódicos da CAPES

Viewpoint 3

2008; Wiley; Volume: 17; Issue: 3 Linguagem: Inglês

10.1111/j.1600-0625.2007.00665_3.x

1600-0625

Mario A. Trelles, Serge Mordon, R Glen Calderhead,

Skin Protection and Aging

Excessive skin exposure to solar UV brings about detrimental histological changes in the skin, which combine with and accelerate the effects of chronological ageing, and which result in the lax, dull and wrinkled appearance of ‘old’ skin. UV photochemically generated oxidative stressors such as singlet oxygen damage matrix integrity; elastosis-inducing damage to the underlying connective tissue occurs, with interstitial spaces appearing in the matrix caused by loss of collagen volume and fibre binding; the viscosity and quality of the matrix ground substance glycosaminoglycans is reduced; and an inflammatory infiltrate can be identified (1). The elegant idea of using light to repair the damage caused by overexposure to light was heralded by the indication of first the CO2 and the Er:YAG lasers in the early 1990s, (2-4) and then a system which combined both wavelengths in the one console (5, 6). Although still regarded as the ‘gold standard’ in the rejuvenation of seriously photoaged skin, laser ablative resurfacing is simply a controlled second degree burn of the dermis and is associated with, at best, unpleasant side effects and a long downtime. A non-ablative approach using lasers and intense pulsed light (IPL) systems delivered a zone of controlled dermal photothermal damage under an intact epidermis to ‘kick-start’ the wound healing process recognized as essential in successful skin rejuvenation. The very good histological evidence of tightening of the typically elastotic dermis failed to be echoed in a younger-looking epidermis, and patient satisfaction with single modality non-ablative skin rejuvenation was extremely low (7-10). The combination of single modality systems based on wavelength-specific photobiological precepts produced much better visible results (11-13). Fractional photothermolysis was next proposed for skin rejuvenation (14, 15), to bridge the gap between ablative and non-ablative technologies by delivering controlled microdamage to both the epidermis and dermis. Some good results have been reported, but patient satisfaction has again been fickle with fractional technology on its own, resulting in the development of a second generation of fractional systems. However, the entrance into the fractional field of CO2- and Er:YAG-based fractional systems is in some way taking us back towards our gold standard of ablative resurfacing, as once again heat deposition, combined with controlled epidermal damage, becomes a pivotal consideration to achieve the ideal rejuvenation results on a patient-by-patient basis, but with minimal downtime. Adjunctive LED therapy given immediately after the fractional procedure has shortened the downtime even further, so LEDs, as discussed below, must be factored into the equation (16). Photodynamic therapy (PDT) with short contact, liposome-delivered 5 aminolaevulinic acid (5-ALA) activated with broadband IPL energy, has recently attracted attention in skin rejuvenation (17, 18). But perhaps the most interesting and exciting advance is the entrance into the photoantiageing arena of LED therapy, based on the ‘NASA LED’ developed in the late 1990s (19, 20). The LEDs offer a solid state, inexpensive, robust, electrically efficient and heat-free phototherapy source. The new LEDs are truly quasimonochromatic with a variance of only a very few nanometres either side of the rated wavelength. When mounted in planar arrays in such a manner that the divergent beams of energy from a large number of LEDs are forced to intersect, the phenomenon of photon interference coupled with the excellent scattering characteristics of light in the red and near infrared wavelengths produces a zone of extremely intense photon intensity beneath the surface of the target tissue in a completely athermal and atraumatic manner. This ensures multiphoton absorption of the delivered wavelength by the cellular chromophores thus raising the target cells’ energy level in what is known as photoabsorption or photoactivation therapy (PAT) and cells can perform their allotted function better or can be repaired if injured or compromised (and what is photoaged skin but a collection of compromised cells). The LED array-based systems are accumulating an impressive body of solid scientific evidence to back up good clinical reports in skin rejuvenation (21-23). Wavelength has emerged as a prime determinant of LED efficacy determining as it does both the target chromophores, and the depths at which these chromophores can be reached. The wavelengths of 633 nm (visible red) and 830 nm (near IR) have emerged, used sequentially and in combination, as the ideal and most photobiologically sound skin rejuvenation protocol. In addition, 633 nm LED energy is an excellent activator of the new liposome-delivered low-strength 5-ALA for painless skin rejuvenation, having much more specificity for the target porphyrins than broad-band IPL energy. We have to ask some important questions, however. What is the point of new technology, if it is not a cost-effective option in these days of spiralling health care costs, both for patient and for surgeon? There appears to be a dazzling range of ‘new’ technology constantly appearing on the market: we have to ask ourselves why this is so. Is it truly patient-driven demand, or is it simply manufacturers leaping on the bandwagon and supplying the aesthetic ‘fashion industry’ with over-rated and over-priced new toys? The major problem as a result of this, we think, is poor examples of good technology muddying the waters for the efficient systems based on the same good technology. Another phenomenon is the very short ‘life’ of some of the new systems: they appear in a blaze of glory, and then simply fade away, due either to the technology being an answer in search of a problem, poorly-thought-out science, the lack of independent clinical results or indeed any good clinical results at all, poor cost-performance, or a combination of some or all of the above. Of these, the presence of solid controlled clinical reports, preferably multi-centric, is probably the keystone to acceptance, backed up by real science in good basic studies. The lack of such results sounds the death-knell for such systems. Overpricing of systems is yet another problem. It is quite possible that price is too often equated with quality, particularly in the higher-end private aesthetic surgical market, where the ‘best boys (and girls) have the biggest toys’, but with a very poor cost-performance ratio. On the other hand, just because LEDs, for example, are much less expensive, does this mean that they therefore have better cost-performance? The answer of course depends entirely on the results, and the results depend on the science on which the system is based and, most importantly, the ability of the clinician to harness that science and get the clinical results aimed for. The ideal for both patient and surgeon must surely be to achieve the best possible results with the least expensive equipment in the shortest time: in this respect we strongly feel that the practitioner should not be a ‘slave to fashion’, but should use whatever systems, stand-alone or most likely in combination, with which he or she feels happiest, based on knowledge and experience, to achieve effective results in as short a time as possible, with as few treatment sessions as possible (24). To return to the theme of LED therapy, and its role in the medicine of the 21st Century, although stand-alone combination 633/830 nm LED therapy has produced significant results, the most appropriate uses for LED therapy are developing as an adjunct to existing skin rejuvenation modalities, surgical or phototherapeutic, such as the very interesting results when fractional technology is enhanced with LED therapy. We believe that a treatment approach which combines epidermis and dermis care to produce an efficient outcome, nut only in one or few sessions, at low risks and without experiencing. Downtime, is the best method to achieve high patients’ satisfaction index, simple due to consistently good skin rejuvenation (25), and because of repair or even reserve the ravages to tissue associated with overexposure to terrestrial solar UV.