Acne Phototherapy - Phototherapy: Laser, Light

Acne phototherapy
Contents
•What is Acne ?
•How does Phototherapy work ?
•Different types of Acne phototherapy ?
•Are small home use devices effective ?
•Blue light acne phototherapy with Accutane.

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What is Acne ?
Acne is a condition of the sebaceous glands that affects 80% of the human population. Acne usually starts in adolescence when hormonal changes cause the enlargement and then the obstruction of sebaceous glands in the skin. The obstruction of the glands’ openings cause the accumulation of sebum, which is followed by abnormal proliferation of bacterial population, predominantly Propionibacterium acnes. (P. acnes) These bacteria attract inﬂammatory cells and thus the unsightly red, painful pustules of acne are formed. These same lesions potentially heal with permanent scarring.

In spite of various available treatments for acne, there are many patients who fail to respond adequately or who develop problematic side effects. Topical acne medications are usually irritating to the skin: more than 40% of acne bacteria are insensitive to oral antibiotics and therapy with oral isotretinoin (Accutane), which is also associated with possible severe side effects and a high cost.

Sun exposure is known to be beneﬁcial in up to 70% of patients with acne. Although solar or artiﬁcial UV light has a mild camouﬂage effect on acne, its comedogenic and photoaging effects prevent its use in acne therapy.

How does Phototherapy work ?
Phototherapy for acne is based on the fact that P. acnes, the bacteria that populate the sebaceous gland, produce porphyrins as part of its normal metabolism. Exposing these compounds to special wavelengths in the red or, preferably, violet-blue visible light range starts a chemical reaction that produces peroxide, able to kill the bacteria. The reaction takes milliseconds and is conﬁned to the bacteria, thus having no direct effect on the surrounding tissue. Blue-violet light (405–420 nm) has been shown to be 10 times more effective than red light (630–670 nm) in triggering excitation of coproporphyrines. Ashkenazi et al cultured P. acnes anaerobically for 72 hours in a liquid medium and illuminated dishes twice (24–48 h interval) for 60 minutes with intense, narrow band violet blue light (405–420nm). At these conditions, the viability of the culture was decreased by four orders of magnitude compared with the control, untreated bacteria.

In Vivo , Skin bacteriology research performed at the Department of Dermatology, SUNY Health Science Center in Brooklyn, New York has shown a decrease in one order of magnitude of the bacteria count on all individuals that had P. acnes counts greater than 100,000 per cm square. Shalita et al have also shown a significant anti inflammtory effect of the 420 nm light.

Harth and associates and multiple others have shown more than 80% of treated patients respond to 420 nm acne phototherapy with a signiﬁcant reduction of 60%-70% of inﬂammatory acne lesions after only eight treatments of 15 minutes. Reduction in lesions was steady at follow-up 2, 4 and 8 weeks after the end of therapy. Prolonged remissions were evident after the end of therapy. No adverse effects or patient discomfort was noted in any of the treated patients.

Different types of Acne phototherapy ?
UV light and even X Ray were used in the past for therapy of Acne. These methods were of course abandoned due to their short and long term possible side effects. In the eighties and ninties, different researches tried red light for the therapy of acne with mixed results. A major advancement in the field was the use of high intentensity, UV free, blue light by Harth and Korman (US Patent 6835202). The system based on their invention supllied for the first time high intensity of blue light - that was found to be 5 -10 times more effective in the photodestruction of acne bacteria than red light. Safety fo therapy was assured by total elimination of UV light. The system that was the first to be approved by the FDA for Acne photherapy was the ClearLight Therapy System, a high-intensity, computerized, UV-free, non-coherent light source, emitting visible light in the violet-blue range with irradiance ranging between 502 and 200 mW/cm2. Smaller systems using LED light were also developed - usually supllying significantely lower energies of blue or red light.

Are small home use devices effective ?
In Vitro research have shown that a threshold energy needed for Photodestruction of acne bacteria. Although Multicenter reasrearch ckinical trials have shown the efficacy of leading high intensity blue light acne photherapy proffesional devices such as the Clearlight or iClear, effeicacy of small home devices is yet to be proved.

Blue light acne phototherapy with Accutane.
Accutane is a very effective oral therapy for the severe cases of Acne. Unfortunately its use is frequently associated with adverse effects among them the possibility of flare of the acne, after 4-8 weeks of treatment. This flare up may results in deeper scars.
Fournier et al have shown in a controlled study that using high intensity blue light therapy in combination with Accutane have significantly decreases the flare up associated with Accutane and resulted in faster and safer therapy of acne.
http://www.radiancy.com/int/lheacne.htm

Acne is a disease of sebaceous glands. Caused, many believe, by an increase in hormones brought on by the onset of puberty. Although primarily a ‘teenage’ affliction, acne has been known to continue well into adulthood and in some has become a life long battle.

Acne Factors
There are several factors that contribute to acne and its proliferation. The key players however are the hair follicles and sebaceous glands. The hair follicle is a small tubular cavity from which hair grows and into which the sebaceous glands open. Hair follicles are found everywhere on the body except the palms of the hands and the soles of the feet.

The sebaceous glands are small oil producing glands that open into the hair follicle and whose general purpose is to keep the hair and skin lubricated. The sebaceous glands produce an oily substance called sebum that drains into the follicular canal and eventually onto the surface of the skin. Sebaceous glands are found most often on the scalp, face, and upper body. During adolescence, increased hormone levels enlarge the sebaceous glands and cause them to produce more sebum than usual. The sebum mixes with dead skin cells and forms a plug that closes the follicle openings. This results in a build-up of sebum, followed by an over-development of the bacterial population due to a nutrition rich anaerobic environment. If not treated the bacteria commonly reach toxic levels that sometimes break through the follicle wall and cause inflammation and breakouts on the skin.

Propionibacterium, also known as P.acnes bacteria, is a common anaerobic bacteria and is believed to be one of the major causes of acne. P.acnes colonization begins during the 1-3 years prior to sexual maturity when its presence on the skin rise from fewer than 10/cm 2 to approximately 106/cm 2.
As part of its metabolism process P.acnes bacteria secrete a pigment known as porphyrin. When stimulated, porphyrin produces a molecule of singlet oxygen within the follicle. This oxygen in turn attacks the P.acnes bacteria ultimately destroying it. The goal of acne phototherapy therefore, is to stimulate the porphyrin to produce oxygen.

LHE Phototherapy
Since its development, LHE has made tremendous strides in acne clearance and has been found to be a very effective treatment modality. In clinical trials LHE has demonstrated up to 90% clearance of acne lesions after an 8 session, 4 week treatment course.

The efficacy of LHE treatments depends on its reliability in producing the required photochemical reaction from porphyrin activation to oxygen production. This reliability is based on three controlled parameters, those of wavelength, temperature and overall concentration of photons.

Wavelength
Although porphyrin is thought to be most reactive to wavelengths in the 400-430nm blue spectrum and is often chosen for acne devices, it continues to absorb photons throughout the visible spectrum albeit to a lesser degree.
One of the main challenges of acne light therapy has been overcoming the conflict between the depth at which p.acnes and porphyrin are found in the follicle and the relatively shallow penetration depth of the commonly used blue light spectrum.
To optimize the tradeoff between the penetration depth required and the porphyrin activation efficacy LHE utilizes a higher range of the light spectrum including green, yellow and red. It is thought that by offsetting the loss in absorption with a more direct targeting of actual porphyrin less photons are wasted at ineffectual depth penetrations.

Temperature
The Arrhenius equation describes the rate of production of excited porphyrin molecules as a function of temperature. For most chemical reactions elevating the temperature by 10°C will double the speed of the reaction.
By combining direct heat with the light pulse LHE further raises the temperature inside the follicle affecting a much faster chemical reaction time than light alone would generate.
The generated heat also serves to reduce the inflammation, open the pores and soothe the painful lesions often associated with acne.

Photon Concentration
To deliver the maximum concentration of photons, LHE technology uses an extra large spot size.