The regions of the body that are most commonly affected in psoriasis include the knees, elbows, scalp, nails and lower back (sacrum), however, the body in its entirety may be affected. The severity of the condition is measured by assessing the total body area involved in the disease (plaque severity). The different variants of psoriasis include, chronic plaque psoriasis (psoriasis vulgaris) (Griffiths and Barker, 2007), flexural psoriasis (inverse psoriasis) (Laws and Young, 2010; van de Kerkhof et al., 2007), guttate psoriasis (Krishnamurthy et al., 2010), erythrodermic psoriasis (Laws and Young, 2010), palmar-plantar psoriasis, facial psoriasis, and scalp psoriasis, and, almost all the variants result in great morbidity and diminished quality of life for the patient (Finlay et al., 1990).
Some of the therapeutic modalities, implemented for the treatment of psoriasis, include topical agent use, systemic drug administration, photodynamic therapy (PDT), UV phototherapy, and laser therapy. Psoralen combined with UVA and UVB phototherapy provided a revolutionary means for the treatment of psoriasis, when it was initially introduced. However, some later studies suggested that, repeated and excess exposure to UVB radiation put individuals at an increased risk for developing skin cancer. Thus, Psoralen + UVA (PUVA) was introduced as a therapeutic modality, with a reduced risk of developing cancer, but its use was still restricted as it did not completely eliminate the risk of cancer.
Studies investigating the use of LLLT for treatment, with CO2 ablative laser (Bekassy and Astedt, 1985), helium-neon lasers (Colver et al., 1984), and red light photodynamic therapy can be dated to the 1980s (Berns et al., 1984).
The laser treatment was effective in that it prevented epidermal cell replication while also suppressing the localized immune responses and thereby reducing the characteristic inflammation observed in psoriasis (Railan and Alster, 2008). However, uncertainty exists regarding the carcinogenic ability of long-term excimer laser exposure. Thus, pulse dye laser (PDL) possessing a wavelength of 585 nm was suggested as an alternative. PDL lasers are commonly used for the treatment of vascular disorders, and thus, have proven to be a legitimate treatment modality for psoriasis due to, the association of increased vascularity with psoriasis (De Leeuw et al., 2009; Ilknur et al., 2006).
Furthermore, a recent study which investigated the efficacy of combination 830 nm (NIR) and 630 nm (visible red light) LLLT, for the treatment of recalcitrant psoriasis, has facilitated the consideration of LLLT for the treatment of plaques associated with psoriasis. In the study, patients that presented with psoriasis resistant to conventional treatment were administered sequential treatments with 830 nm and 630 nm wavelengths for two, 20-minute sessions, spaced 48 hours apart for a total of 4 or 5 weeks.
The results from the study did not display any adverse effects; rather, the results demonstrated resolution of psoriasis (Ablon, 2010). Although the study was promising, it was limited by its small sample size; however, the results of the study provided motivation for future investigations to look at the applications of LLLT as a therapeutic modality.