A bright solution to our problems for everyone?
Laser therapy has provided numerous breakthroughs in the treatment of many dermatological conditions. Moreover, lasers are dubbed as “lunch-time procedures” simply because of the low downtime and ease of administration that it promises. Therefore, it is not difficult to see why laser therapy is the “go to” treatment for many.
The reason behind its effectiveness is because the laser light can be precisely directed at small areas with very high energy. The goal is to focus the treatment at target cells or areas and avoid harming the surrounding tissues. Additionally, because short pulses of energy are given off, this once more aids in minimising the heat that the cells are exposed to and hence lower the scarring risk secondary to thermal injury.
Although laser therapy has a marked influence on numerous people’s pursuit of beauty today, there is seemingly a group of people who are neglected—the darker skinned individuals. For decades, laser therapy has almost been exclusively recommended for those with fairer skin owing to the mechanism of action of lasers that put the darker skinned individuals at higher risk of adverse effects such as scarring and hyperpigmentation or hypopigmentation and for some, ineffective treatment.
In spite of the increased demand for dermatological laser treatments by African Americans, Hispanics and darker skinned Asians, a survey revealed that a bulk of the research is still being dedicated to improving and expanding the laser treatment options for individuals with fair skin tones.
As such, this article serves to explore the secrets of why dark skin and lasers are not compatible and the solution for this group of individuals.
Why lasers and dark skin are not meant to be
In order to understand why dark skin is a relative and for some, absolute contraindication for laser therapy, we need to know the difference between dark skin individuals and their fair skin counterparts. Melanin is a pigment found in our skin in varying percentages and it makes that area dark. Dark skin people have a much higher percentage of melanin in their skin as compared to fair skin people.
Most dermatological lasers currently in the market can target melanin. Research shows that in individuals with Fitzpatrick skin types III and IV, more light energy is absorbed as opposed to individuals with skin types I and II. When a higher amount of laser light energy is absorbed, this renders dark skin individuals a higher risk of adverse side effects – scarring, changes to the texture of their skin and hyperpigmentation or hypopigmentation – because of unintended and nonspecific thermal injury to the melanin in their skin. Additionally, prior history of treatments such as chemical peels or dermabrasion is important because these cause skin trauma and thus increase the individual’s risk for pigmentation.
Next, the large melanin deposits present in the epidermis serve as competition for the laser light energy. It rivals with the deeper dermal lesions that actually need to be targeted during the treatment and ultimately impedes the amount of laser light energy that these target spots need to receive. Hence, the desired clinical result is not achieved and this explains the reason why lasers are not as effective in dark skin individuals.
It is important to also recognise that these well-documented adverse side effects that dark skinned individuals suffer from are harder to conceal and appear more pronounced on their skin.
In light of all of this, it is apparent that laser therapy and dark skin are a pair not meant to be.
New research and hope for dark skinned individuals!
Despite the aforementioned pessimistic explanation on why laser therapy is not suited for dark skinned individuals, there has been some research poured into this area. There are namely 2 paramount findings which reveal how laser treatments can and now are being bettered to allow laser energy to be less efficiently absorbed by endogenous melanin. This way, a greater margin of safety is provided and decent results can be achieved for dark skinned individuals.
Firstly, research has revealed that the absorption of laser light energy by melanin decreases significantly when the wavelength of light increases. Therefore, this implies that it longer wavelengths of light are used, greater penetrance through the layers of skin to reach the target spots effectively can be achieved.
Apart from taking into consideration the wavelength of light, the power level of the laser treatment is essential to bear in mind as well. Various studies have shown that skin with a large amount of melanin deposits (present in dark skinned people) absorb electromagnetic energy much more efficiently than people with a smaller amount of melanin deposits (present in fair skinned people). In fact, Fitzpatrick skin type VI absorbs approximately 40% more energy when irradiated by a light laser as compared to a Fitzpatrick skin type I or II, when fluence[1] levels and exposure duration remain constant. Hence, it is recommended that irradiation test spots be carried out for the patient in order to individualise and adjust the power settings accordingly to achieve satisfactory results safely for the patient. This however may mean more laser treatments are necessary in order for maximum clinical results to be achieved for dark skinned individuals.
Lasers that are suitable for dark skinned individuals
Owing to the fact that lasers have innumerable uses, this article will just be touching upon 4 key dermatological areas that laser therapies are used in and how they have current modifications and innovations to extend its use to include dark skinned individuals.
For one, laser therapies can be used to target pigments on the skin such as sun spots, age spots, post inflammatory hyperpigmentation and freckles. Lasers used for this purpose can also be used for the removal of tattoos. Out of the numerous types of laser treatments available, the alexandrite and Nd:YAG laser systems are the safest for dark skinned individuals. The two utilise wavelengths of light that are less efficiently absorbed by epidermal melanin and hence reduce unwanted and unintended thermal injury to the innocent surrounding areas of skin. In the removal of tattoos, unpredictable tissue response needs to be anticipated. This is because there are numerous different pigments present in a tattoo. While the Q-switched 694 nm ruby laser is very effective in removing blue and black tattoo pigments, epidermal melanin strongly absorbs it and hence this laser puts dark skinned individuals at a higher risk of adverse side effects. Thus, alexandrite and Nd:YAG lasers still provide a safer and yet still efficacious alternative. In recent years however, the pico laser has been getting more recognised for its effectiveness and safety profile in dark skinned individuals. It has also proven itself to be the most efficacious in removing tattoos according to statistics. Its quicker pulse speed as compared to other laser systems allows the pico laser to generate less heat and for this reason, minimises the risk of scarring when being used on dark skin tones.
Skin resurfacing with laser treatment is another common function of lasers today. Broadly, skin resurfacing can be divided into ablative and non-ablative forms with the former being associated more with side effects such as post treatment pigmentation. They serve as an effective way to improve one’s appearance and target dermatological conditions such as atrophic scarring, diffuse dyschromia and acne. It is important to note that acclaimed lasers such as the carbon dioxide laser and erbium:YAG that are used in skin resurfacing are unable to achieve the degree of cosmetically pleasing results in those with darker skin as opposed to those with Fitzgerald skin type I and II. In spite of this, several studies still document a high rate of satisfaction amongst dark skinned users. To reduce the side effects faced by dark skinned individuals after laser skin resurfacing procedures, there must be strict adherence to these few rules:
1. Avoidance of excessive sun exposure
2. Consistent use of full-spectrum sunscreens at least 3-4 months prior to laser treatment and immediately after treatment
Interestingly, several studies show that pre-treatment with retinoic acid aids in increasing cell turnover rates and thus skin healing and it also reduces melanin production post laser treatment. Hence while it does not eliminate the occurrence of post treatment hyperpigmentation in dark skinned individuals, it does help in minimising its severity and time the pigmentation spots take to recover. To add on, topical hydroquinone and glycolic acid creams have also been found to speed up the resolution of post laser hyperpigmentation in dark skinned individuals.
Non-ablative skin resurfacing lasers on the other hand are generally considered to be safe to treat acne or acne scarring in patients with darker skin. This is because the wavelengths of light used in the laser can be thought of as being “colour blind”.
Next, vascular lesions are also able to be targeted with laser therapy. Some examples of vascular lesions on the skin include hemangiomas, facial telangiectasias, hypertrophic scars, port-wine stains and post-acne redness. Currently, the 585nm pulsed dye laser has secured its place as the laser with the highest efficacy and best safety profile in treating vascular lesions in individuals with darker skin. Although post inflammatory dyspigmentation (hyperpigmentation and/or hypopigmentation) may be expected post treatment, it is usually transient and the risk of developing dyspigmentation are addressed with new skin cooling techniques. Apart from the 585nm pulsed dye laser, the Vbeam laser (also another pulsed-dye laser), which is commonly used to target red pigment in the skin is currently now another viable option for people with dark skin and vascular lesions such as rosacea and spider veins. The crux lies in toning down the speed and temperature of the Vbeam laser when it is being used in dark skinned individuals.
Hypertrichosis[2] and hirsutism[3] are problems that can be addressed with laser treatment as well. However, the efficacy of tackling the hair follicle is impeded by competition from epidermal melanin as explained earlier. 800nm diode lasers and 1064 nm Nd:YAG lasers are associated with a lower melanin absorption compared to other laser options and are thus more effective for use in patients with darker skin. Precautions such as low laser fleunces still should be taken so as to allow for a safe administration of the laser.
Conclusion
Hopefully this article has served its purpose to provide more insight into the complications that dark skinned individuals face relative to their lighter skinned counterparts and how these adverse side effects can be reduced with the institution of conservative treatment parameters; lower electromagnetic power settings and longer wavelengths of light. Having said this, it is vital for clinicians to properly educate their dark skinned patients on this as well so as to manage their expectations and provide them with the necessary precautions being taken.
In good faith, more focus will be directed at this area and with further research, eventually new laser treatment options will be brought into the market to provide novel and refined laser solutions for patients of all skin types.
References:
- Davis, Erica C, and Valerie D Callender. “Postinflammatory Hyperpigmentation A Review of the Epidemiology, Clinical Features, and Treatment Options in Skin of Color.” Postinflammatory Hyperpigmentation A Review of the Epidemiology, Clinical Features, and Treatment Options in Skin of Color, July 2010, ncbi.nlm.nih.gov/pmc/articles/PMC2921758/.
- Cole, Patrick D, et al. “Laser Therapy in Ethnic Populations.” Laser Therapy in Ethnic Populations, 2009, ncbi.nlm.nih.gov/pmc/articles/PMC2884928/.
- Alster, Tiner S, and Elizabeth L Tanzi. “Laser Surgery in Dark Skin.” Laser Surgery in Dark Skin, Medscape, medscape.com/viewarticle/451058_1.
[1] Definition of fluence. 1: the number of particles (such as photons or neutrons) incident on a sphere divided by the cross-sectional area of the sphere 2: the total number of particles per unit area with which a material is irradiated particle fluence.
[2] Excessive hair growth over and above the normal for the age, sex and race of an individual
[3] Excessive hair growth in women following a male distribution pattern
