IPL, like lasers, works on the principle of selective photothermolysis, first described by Anderson and Parrish in 1983.9 The target structures may have different absorption maxima such as hemoglobin absorbs at a wavelength of 580 nm while melanin has a spectral range of 400–750 nm. Longer wavelengths are absorbed lesser by the melanin and penetrate deep, thus reaching deeper blood vessels and avoiding epidermal damage. The bandwidth of IPL is modified by application of filters which exclude the lower wavelengths. In that spectrum, during a 10 ms pulse, relatively high doses of yellow light at 600 nm are emitted and other wavelengths are emitted much less.4 This wavelength facilitates selective absorption by bright red superficial vessels.

Vascular lesion treatment filters require filters such as 515, 550, 560, 570 and 590 nm. Hair removal can be performed using longer filters such as 615, 645, 695 and 755 nm. These filters can also be used to cause fibroblast stimulation.

Spot size along with wavelength affects penetration depth. Smaller the spot size, more rapid the scatter and more rapid the decay of fluence by depth (Table 1). Thus larger spot size would result in greater amount of energy being delivered to the skin. The light emitting planar surface of the IPL device functions through a water-based interface between the crystal and the skin. This water based gel, as mentioned earlier has functions of enhancing optical coupling, minimizing reflections, acting as a “heat sink” and maintaining continuity of index of refraction of the skin/air interface. The gel also helps filter higher wavelengths, thus removing some of the ineffective or potentially tissue damaging near-infrared wavelengths before being absorbed by the target. In order to treat deeper or larger vessels, the fluence can be modified and increased and the gel can be chilled to protect the overlying epidermis. A 1–2 mm layer of chilling gel can be used between the crystal and the skin when working with a large footprint of IPL, as has been termed as “floating” the crystal. This is especially useful when an integrated chilled crystal is not being used.

Between two pulses, some amount of time is allowed for the epidermis to cool down and is referred to as thermal relaxation time (TRT). More accurately defined TRT is the amount of time taken for the temperature of a tissue to decrease by a factor of ε  =  2.72 as a result of heat conductivity. TRT helps to prevent the elevation of epidermal temperatures above 70°C and prevents epidermal damage.

Epidermal thickness of 100 μ has a TRT of about 1 ms, a typical vessel of 100 μ has a TRT of approx. 4 ms. This can be used to predict that vessels greater than 300 μ would have a TRT of more than 10 ms and thus these vessels will cool more slowly than the epidermis, with a single pulse. For larger vessels, multiple pulses prove more advantageous with 10 ms or more delay times in between the pulses for epidermal cooling. The treatment of darker skin individuals (Fitzpatrick IV–VI), and/or patients with hyper-reactive melanocytes should be performed very carefully, best by using a 755 nm filter with a pulse delay of 50–100 ms, to allow sufficient cooling time for the epidermis. When treating leg veins, better results have been obtained with longer pulse duration (up to 50 ms).10

A study conducted to understand the principles of “double or multiple pulsing” using a 585 nm yellow dye laser on larger vessels of Port wine stains, showed that these vessels absorbed greater energy fluences before reaching purpura after double pulses spaced 3–10 ms apart.11 After a pump pulse delivering 80% of the fluence necessary for causing purpura, the fluence of a second probe pulse necessary to cause purpura was determined and was found to increase the interval between the two pulses, in a manner consistent with the thermal diffusion theory. For a small vessel (0.3 mm), heat distribution was assumed to occur instantaneously. For a larger vessel, heat had to pass from the inside of the superficial vessel wall and through the vessel to the deeper wall. Larger vessels required longer cooling time periods for the accumulated heat inside the core. These principles are effective when using a double pulse 585 nm yellow dye laser in the treatment of larger vessels of PWS (larger than 0.1 mm). After double pulses spaced between 3 and 10 ms apart, larger vessels absorbed greater energy fluences upon reaching purpura.11

A study using pulsed laser irradiation at 585 nm with short pulse (0.45 ms) and long pulse (10 ms) durations showed that long-duration pulses caused coagulation of the larger diameter vessels. Small caliber vessels and capillaries demonstrated resistance to photothermolysis.12 The use of IPL with extended pulse durations from 12–50 ms has caused larger vessels (0.5 mm or greater) to undergo more clinical photothermal coagulation while sparing the epidermis.6

Leg telangiectasias are visible, ectatic dermal arterioles, capillaries, or veins with a diameter of 0.1–1 or 2 mm. The chromophores for vascular lesions are represented by the hemoglobin and its derivates: oxyhemoglobin, deoxyhemoglobin, and methemoglobin.13 Each target chromophore has a variable spectrum of light absorption. Oxyhemoglobin has a very high coefficient of absorption up to 630 nm, although the absorption is poor at longer wavelengths and increases again in the near infra-red range of 800–900 nm. Deoxyhemoglobin absorbs in the range of 600–750 nm, and unlike oxyhemoglobin, does not drop as much as 600–750 nm. Blue leg telangiectasias are slightly more deoxygenated compared to red telangiectasias.14 Additionally, when a vessel is treated with multiple closely spaced pulsing (up to 20 ms), oxygenated hemoglobin is converted to deoxygenated hemoglobin during the first portion of sequential pulsing, leading to predict that 600–750 nm range is preferable for treating relatively deoxygenated blue leg telangiectasias. Shorter wavelengths have been found to be effective in treating superficial red vessels, but are refractory in terms of treating deeper blue venulectases and reticular veins. These findings can be attributed to the following reasons:

Use of multiple devices in combination may be necessary for lower extremity vessels. For example, red vessels <1 mm in diameter can be treated with 578 nm KTP laser, 585–600 nm PDL, 532 nm Copper bromide laser and 500–1,200 nm IPL source, and blue vessels 1–4 mm in diameter can be treated with 755 nm Alexandrite laser, 800 nm Diode laser and 1,064 nm Nd:YAG laser.18 Longer wavelengths may be used to treat larger diameter blue venulectasia and small reticular veins.

A great advantage of IPL devices is that the parameters are adjustable in a way that the risk of epidermal injury is minimized. This can be done by proper selection of fluence levels, pulse type, wavelength, delay periods and always cooling of the skin immediately after treatment. The bigger the spot size is also important; the bigger the spot size, the more area is covered and more light penetration is assured.19

The lasers currently available to eradicate leg veins emit green light (532 nm), yellow light (578–600 nm), red light (755–810 nm), near infrared light (1,064 nm), and a broad spectrum IPL (515–1,200 nm).20 With appropriate wavelength matching for specific vessel color, luminal diameter and depth, improved results have been achieved. Extended pulse durations, higher fluences and improved contact and dynamic cooling technologies; contributed to more reliable clinical as more energy can be delivered while sparing the epidermis.

Clinically, telangiectasias can be classified as linear, arborizing, spider and punctiform.24 The reason for the development of facial telangiectasias in most cases is unknown, but sun exposure, topical or systemic steroids and hormonal replacement therapy play a role. Facial telangiectasias on nose and cheeks are a cosmetic blemish for many a patient. IPL and lasers have been very effective in improving these telangiectasias.25 PDL with 0.5 ms pulses are the most preferred way of treatment but intracutaneous hematomas have frequently been encountered.25 ’ 26 (Fig. 1a, b) On the other hand, IPL systems have less of these side-effects and have become increasingly popular for telangiectasia treatment.7 ’ 27 Clearance rates of 75–100% have been achieved in treating patients with essential telangiectasias, as demonstrated on 153 such patients by Angermeier.28 In another study by Schroeter et al. achieved 90–95% clearance in one session with PhotoDerm VL in 45 patients with telangiectasias and spider nevi.29 Clementoni et al. demonstrated a 75–100% clearance but did not find any correlation with lesion size, age, skin type but was related to operator’s experience.30

Erythematotelangiectatic (ET) rosacea clinically manifests as facial telangiectasias, persistant erythema and flushing involving the central face. PDL at wavelengths of 585 and 595 nm, have been used and considered to be an effective modality for their treatment.31 ’ 32 But, purpura was frequently a less tolerated side-effect of PDL treatment, which was quite a lot improved with the modifications that were introduced such as the use of higher fluences and incorporation of cooling devices. Besides, cryogen cooling sprays also aided much in protecting the epidermis while still delivering the heat sufficiently to target the deeper vessels.33 On the other hand, the main advantage with the IPL device is the absence of post-operative purpura when treating vascular lesions. In fact, in a study with 29 patients, a comparison was made between the nonpurpuragenic PDL and IPL treatment in the ability to reduce erythema, telangiectasia and symptoms in patients with moderate facial ET rosacea. With split face treatments with IPL/PDL, PDL/no treatment and IPL/no treatment combinations in three groups of patients, it was observed that both IPL and PDL had similar efficacy and safety and both modalities were reasonable choices for treating ET rosacea.

Schroeter et al. in a study to test the effect of IPL on 60 patients, observed that an average of four treatments, 77.8% clearance of facial telangiectasias occurred. The forehead showed the best (87%) clearance.34 Of the different, sites treated, the nose needed the maximum number of treatments (five) for the lesions to disappear. They also observed and suggested that IPL has the following advantages in treating facial telangiectasias over other lasers:

A case of hereditary benign telangiectasia treated with 12 treatments of IPL in 18 months and the condition showed vast improvement.35

Hemangiomas are characterized by a proliferation growth phase followed by slow, inevitable regression (involution phase) between 1 and 10 years of age. Although hemangiomas resolve, lesions persist in 35–50% of children who begin school.36 Even after spontaneous involution of the lesions, 15% of children have residual skin changes, including depigmentation or hyperpigmentation, telangiectasia, atrophy and wrinkling of the skin, and cutaneous depression. If skin changes occur, remaining changes of the skin may correspond to the largest size of the hemangioma.37 However, spontaneous regression is no guarantee of a satisfactory cosmetic result, as is often presumed.

Various lasers, particularly the flashlamp-pulsed dye laser, have been proven to be effective in the treatment of hemangiomas.38–42 (Fig. 2a, b) Nevertheless, the post-treatment side effects, such as pronounced purpura and changes in pigmentation, have been a matter of concern until longer pulse durations became available.

Ulceration is the most common complication of infantile hemangiomas and poses a therapeutic challenge due to associated pain, infection, hemorrhage and subsequent scarring. In a report on the use of an IPL system in the treatment of ulcerated hemangiomas in a 4-month-old girl, with hemangioma affecting the entire cutaneous surface of the left limb and development of four ulcerations on the inner aspect of this extremity.43 Two sessions with an IPL system using a triple pulse mode; (a 570-nm lower cut-off filter and a fluence of 38 J/cm²) were performed. Good results were rapidly obtained after two and four sessions of IPL treatment, respectively. Pain was soon relieved and complete epithelization was obtained by between 1 and 2 months in both patients. Yet, due to the pain being a very commonly associated complaint and more complications occur while treating hemangiomas with IPL, pulsed dye laser is still the preferred method of treatment for initial superficial hemangiomas.44

Poikiloderma of Civatte (POC) is a common manifestation of photoaging and presents as erythematous, pigmented and finely wrinkled appearance of the skin in sun exposed areas mainly on the neck, forehead and upper chest, with sparing of submental area.

Because of their ability to target vascular and pigment abnormalities simultaneously, IPL is an ideal device to treat POC. The use of 515 nm filter allows absorption, both by melanin and hemoglobin simultaneously. In patients with more dyspigmentation, initial use of higher filters (550 and 560 nm) prevents too much epidermal absorption and thus avoids crusting and swelling. Additional treatments with IPL using 550, 560 or 570 nm filter to treat the vascular component of POC may be required. Patients with severe form of POC may need initial treatments to begin with 590 nm filter followed by the use of lower ­filters. In different studies, a clearance of more than 75% of telangiectasias and hyperpigmentation was observed. An incidence of 5% of side effects including pigment changes has been seen.45

Although PDL has been proven to be the preferred treatment for port-wine stains (PWS) in children and adults, lesions with nodular parts and hypertrophic and extended PWS may not achieve great outcomes, thus making it necessary to look out for more options.46–48 The reason for the resistance to treatment with PDL is probably the large size and the greater depth of the vessels in PWS.11 ’ 49 (Fig. 3a, b)

In a certain multi-center study, it was shown that PhotoDerm VL yielded good results in both therapy resistant and hypertrophic PWS (Table 2).4