A KTP laser is a solid-state laser that uses a potassium titanyl phosphate (KTP) crystal as its laser medium. The KTP laser medium is energised through a beam generated by a neodynium:yitrium aluminium garnet (Nd: YAG) laser. This is directed through the KTP crystal to produce a beam in the green visible spectrum and has a wavelength of 532 nm.
The selected wavelength of laser light is absorbed to a high degree by the target structure (called a chromophore), and is absorbed less by surrounding tissue.The skin chromophores targeted by the KTP laser are melanin and oxyhaemoglobin.
The pulse duration of laser energy is shorter than the target structure’s thermal relaxation time, which is the time taken for the target to cool by 50% of its peak temperature after irradiation. This ensures that the impact of thermal energy is limited to the target structure and does not affect the surrounding tissue.
Absorbed energy is most responsible for the clinical effect because it is converted to thermal energy (heat) by the intended targets (chromophores), thereby killing the target cells. The effects of the KTP laser on the skin can be modified by altering the pulse width and degree of cooling.
Best responses for port wine stains were found with fluences ranging from 18 to 24 J/cm2 with pulse width 9-14 ms and wavelength 532 nm.
Successful treatment has been achieved with KTP laser: 15-J/cm2 fluence, 10-msec pulse duration, 1-mm spot size, 3-Hz pulse rate, 5-15 pulses per lesion, 2 treatment sessions.
Patients usually prefer KTP laser treatments of cutaneous vascular lesions to pulse dye laser because of less discomfort and minimal purpura post-treatment.
KTP laser has been shown to be beneficial for the removal of sun spots (lentigines) and freckles in fair-skinned (Fitzpatrick skin types I–III) individuals.
For seborrhoeic keratosis, dermatosis papulosa nigra and skin tags 1-2 sessions of KTP laser treatment are required at high energy settings to ablate the raised tissues.
KTP lasers activate the bacterial porphyrins of Propionibacterium acnes, the causative bacteria of acne. Activation of the bacterial porphyrin releases free radical molecules, which can kill the bacteria.
KTP lasers have been reported effective in rosacea. Usually 1 to 3 treatments are required at monthly intervals.
Used in the Q-switched mode, the KTP laser can be used to remove red-coloured tattoo ink.