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Currently, there is a lack of effective treatments for dense comedones. Comedo squeezers have been widely used by dermatologists, but they have only temporary effects and may cause irritation. Carbon dioxide (CO₂) lasers can be used to treat dense comedones, but their efficacy and safety remain to be explored. This study used a single-center, randomized, single-blind, self-controlled design to randomly assign the faces of patients with dense comedones to two sides, one side receiving ultra-pulse dynamic CO₂ laser treatment and the other side receiving comedo squeeze treatment; once every two weeks, for a total of 4 times.
After 4 treatments
① The average acne reduction rate of CO₂ laser is 64.49%, which is much higher than the 46.36% of squeezers. 79.16% of patients reduced their acne by more than 50% after CO₂ laser treatment, while only 37.5% of patients achieved a 50% clearance rate on the squeezer treatment side.
② After treatment with both methods, the skin texture index, porphyrin index, red area, erythema index and transepidermal water loss all decreased, and CO₂ laser showed more improvement.
③There was no difference in moisture index and melanin index between the two treatments. No persistent or severe side effects were observed on either side. CO₂ laser was more efficient in removing acne and less painful than comedone squeezer.
Introduction
Comedones are likely to be formed due to abnormal proliferation and differentiation of keratinocytes in the infundibulum. According to their morphology and size, comedones can be divided into fine comedones, common comedones, sandpaper-like comedones, and large comedones. According to the acne assessment scale, comedones between 20 and 50 are grade II, 50 to 100 are grade III, and more than 100 are grade IV (dense comedones). Although comedones are considered non-inflammatory lesions in clinical manifestations, recent studies have shown that inflammatory factors are present in the process of comedonogenesis. Therefore, comedones are likely to develop into inflammatory skin lesions, especially dense comedones. In order to limit the progression of acne, controlling comedones is a key link. Comedones were once considered mild to moderate acne vulgaris, so topical medications are often recommended in clinical guidelines. Currently, the first-line treatment for comedones is topical retinoids, but the irritation of these drugs limits their use. These topical medications have some effect on grade I and grade II comedones (smaller in number and smaller in size), but have little effect on grade IV comedones. Oral isotretinoin can also be used to treat acne, but its teratogenicity, hepatotoxicity, and acne outbreaks after use make patients psychologically resistant. In addition, there are some physical therapies, including the use of comedone squeezers, syringes, tweezers and other tools to remove acne.
CO₂ laser or comedonal squeezer
The comedone squeezer was first invented by Dr. Henry Piffard in 1873, and has since undergone a series of improvements and evolutions. Most modern comedone squeezers widely used in clinical practice are made of titanium alloy, with one end sharp for piercing the skin surface and the other end equipped with a blunt squeeze ring to assist in squeezing out the contents. This tool is easy to operate and its cost is gradually decreasing, so it is widely used worldwide to assist in the removal of comedones. CO₂ laser is an infrared laser with a wavelength of 10,600 nanometers that targets water. The photothermal, photochemical, and photoacoustic effects of CO₂ laser work synergistically to promote skin regeneration, collagen remodeling, and regeneration. Therefore, CO₂ laser is widely used in the treatment of various skin diseases, such as acne scars, syringoma, onychomycosis, warts, etc. Compared with traditional CO₂ lasers, ultrapulsed CO₂ lasers have higher energy density and deeper penetration, and the dynamic mode makes it more flexible and precise. In this study, a high-energy density method of ultrapulsed dynamic CO₂ laser was developed to achieve better treatment effects and minimize pain. This study aimed to evaluate the efficacy and safety of a comedone squeezer and ultra-pulsed dynamic CO₂ laser for the treatment of dense comedones.
Treatment methods
The treatment endpoint reaction was the appearance of lipid filaments or cracks.
� Comedone squeezer treatment (control side) used a comedone squeezer with a needle on one end and a 5 mm diameter ring device on the other end. First, use the needle at about a 45° angle to puncture the surface of the comedone, then use a ring device to apply light to moderate vertical pressure around the comedone until the contents are squeezed out.
(A) Mean acne reduction rate over time for both groups (n = 24).
(B) Proportion of patients with different reduction rate grades after each treatment for both treatments (n = 24).
(C) Localized acne on the forehead of an 11-year-old female: before treatment (top), after four treatments (bottom); side treatedwith CO₂ laser (left), side treated with comedone squeezer (right).
After four treatments, the acne on the side treated with the CO₂ laser almost disappeared, while the acne on the side treated with the comedone squeezer was reduced but still quite numerous.
(D) Representative images of VISIA image texture masks before (top) and after (bottom) treatment in a 22-year-old woman. The part protruding from the skin (yellow dots) on the side treated with CO2 laser was significantly reduced,
indicating a more significant reduction in acne.
Discuss
This study shows that the ultra-pulse dynamic CO₂ laser is more effective than the comedone squeezer in treating acne. After four treatments, 79.16% of patients achieved a 50% acne reduction, and the average reduction rate of CO₂ laser treatment was 64.49%. On the CO₂ laser treatment side, the decreases in skin texture index (TI), porphyrin index (PI), red zone (RZ) and erythema index (EI) were more significant, indicating that the use of CO₂ laser treatment improves skin smoothness, The reduction of microcomedones and the reduction of the area and degree of skin inflammation are more obvious. The comedone squeezer pierces the epidermis with a needle at one end and squeezes with a ring-shaped device at the other end, which can remove excess sebum, cutin and excessive proliferation of infundibular keratinocytes. It is simple to operate and low in price, so it is widely used clinically. However, it is difficult for operators to control the intensity of squeezing, especially for inexperienced operators. Additionally, comedone squeezers may result in incomplete exfoliation of sebum, which serves as a growth matrix for bacteria and other microorganisms and promotes the development of acne. In addition, squeeze treatments can only target acne that has already appeared on the surface of the skin and cannot prevent or provide deeper treatment. In contrast, CO₂ laser makes up for these shortcomings.
First, the ultra-pulsed CO₂ laser in dynamic mode can precisely target acne. On the one hand, the photomechanical effect of CO₂ laser can destroy abnormal keratin; on the other hand, it helps reshape epithelial tissue and restore the new epidermis to normal. Secondly, the selective photothermal effect of CO₂ laser vaporizes the contents of acne into lipid filaments or solidifies them into particles, which are then discharged through the epidermal channels opened by CO₂ laser. Heat is also transferred to the surrounding of sebaceous glands, causing them to shrink and reduce sebum secretion. Third, CO₂ laser has antibacterial and anti-inflammatory effects. The shock waves generated by the laser can kill bacteria and destroy biofilms, thereby achieving antibacterial effects. Previous studies have found that the levels of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) are reduced after laser treatment, indicating its anti-inflammatory effect. The relief of inflammation may be due to the presence of inflammatory factors and bacterial proliferation in the acne stage, and the process of treating acne is also a process of reducing inflammation and preventing further development of inflammatory acne lesions. The reduction in transepidermal water loss (TEWL) indicated the repair of skin barrier function after treatment, which may indicate a potential relationship between dense comedones and skin barrier, but it is not clear which one occurs first. It is speculated that the destruction of the skin barrier is one of the causes of dense comedones, and the development of comedones further exacerbates the destruction of the skin barrier. There was no significant change in the moisture index (HI) and melanin index (MI), indicating the safety of both treatments. The pain caused by CO₂ laser was much lower than that caused by comedone squeezer, and the difference was statistically and clinically significant, because the minimum clinically important difference in the pain numeric rating scale (NRS) was defined as two units. As for the difference between the number of treatments, it may be related to the number of comedones, and this difference was only statistically significant but not clinically significant. No persistent or severe side effects were observed on both sides. For the urticaria reaction caused by CO₂ laser, the patients had no discomfort such as pain or itching, and these reactions subsided on their own within one hour without leaving any traces. The transient erythema and pigmentation caused by CO₂ laser or squeezing disappeared within 14 days, and at the last follow-up, all patients were free of erythema or pigmentation. Compared with traditional comedone squeezers, ultra-pulsed dynamic CO₂ lasers show higher clearance rates and lower pain scores in the treatment of dense comedones. The high precision and strong penetration of CO₂ lasers make their treatment not limited to the skin surface, but can penetrate deep into the skin to treat and prevent acne from the root. In addition, CO₂ lasers can stop bleeding during treatment, reducing the risk of infection and bleeding. Clinically, CO₂ lasers are easy to operate and low-cost (no consumables are required), which is also a major advantage. However, its long-term effect also comes at a price, that is, there is a scab and shedding process, and the recovery period is longer.
