Is the PALLAS laser as effective as the excimer laser?

The biggest difference is the wavelength and the method of generating the laser.

The existing excimer laser uses gas as a medium to emit 308nm ultraviolet light, whereas the PALLAS laser uses a titanium-sapphire solid crystal to produce a 311nm wavelength.

Like the excimer laser, the PALLAS also allows targeted treatment that selectively irradiates ultraviolet light only to vitiligo lesions.

Unlike whole-body phototherapy, it can reduce unnecessary ultraviolet exposure to normal skin, making it useful for patients with limited lesion areas or for sensitive areas like the face where pigment changes are a concern.

Another advantage of targeted laser treatment is that it can be used for pediatric patients who have difficulty entering a phototherapy unit.

After confirming biological effects in animal experiments, actual repigmentation was confirmed in a preliminary clinical study involving 14 vitiligo patients.

First, in animal experiments, after irradiating with the PALLAS laser, it was confirmed whether the expression of substances involved in the differentiation, proliferation, and migration of melanocytes, such as endothelin-1, stem cell factor, and WNT7a, increased.

As a result, the 311nm laser showed biological responses similar to those of the excimer laser.

Subsequently, 14 patients with vitiligo on the face and neck were treated twice a week with the PALLAS laser in combination with Protopic ointment.

The median number of treatment sessions was 23, and the median treatment duration was approximately 3.7 months.

On average, repigmentation began to appear after about 5 treatment sessions, and ultimately, 11 out of 14 patients (79%) showed 75% or more repigmentation. Among them, 3 patients showed complete repigmentation.

The pattern of repigmentation was also similar to that observed with the existing excimer laser, such as spreading out in spots from around hair follicles or filling in from the edges of the lesion inward.

The PALLAS laser requires higher energy to produce the same skin response compared to the excimer laser.

The minimal erythema dose (MED) of the PALLAS laser was approximately 1.7 times higher than that of the excimer laser.

This difference is due to the different wavelengths and photobiological characteristics of the two devices and does not mean that the treatment efficacy of the PALLAS is inferior.

In actual facial treatment, the excimer laser is started at approximately 150 mJ/cm², and the PALLAS laser at approximately 200 mJ/cm².

Afterward, both devices adjust the energy in increments of 50 mJ/cm², aiming for a level where mild erythema is maintained for about 24 to 48 hours after treatment.

Simply comparing the displayed energy numbers should not be used to judge which device is stronger or weaker.

Additionally, the beam size of the PALLAS laser is 12×12 mm, which is smaller than the 20×20 mm of the excimer laser. Therefore, irradiation time may be slightly longer for larger lesions.

On the other hand, because it is a solid-state laser, it does not require periodic gas refills like the excimer laser.

In terms of vitiligo treatment efficacy alone, both devices can be considered validated options.

Clinical studies have shown that the PALLAS laser provides a level of repigmentation comparable to that of the existing excimer laser, with no significant difference in safety.

Like the excimer laser, the PALLAS laser is also eligible for health insurance coverage for vitiligo treatment, so there is no significant difference in the cost borne by the patient.

Rather, what has a greater impact on actual treatment outcomes is the area where vitiligo occurs and each patient's treatment response, not the name of the device.

This is not due to differences in device performance, but because the distribution and characteristics of melanocytes vary by area. Even on the same face, treatment response may differ between the area around the eyes and the lips. While the face may recover well, both devices may have difficulty treating the hands.