A copper bromide laser produced by Norseld in Adelaide, South Australia, the Dual Yellow has been refined to be more stable, quicker to warm up to active mode, and, with new hand pieces, to be able to treat a wider range of conditions.
The core of the Dual Yellow is the copper halide tube which provides the characteristic light. In contrast to quite a number of other laser sources (excluding tuneable dye lasers) which produce only a single wavelength of laser light, the Dual Yellow produces two – 511nm (green in colour) and 578nm (yellow).
The yellow 578nm corresponds well to a peak of absorption by the haemoglobin pigment in the red blood cells. At this point the absorption is stronger than for the melanin (tan) pigment in skin. Hence it is a good wavelength for treating blood vessels.
The green 511nm light has a stronger affinity for melanin. Therefore the green is useful for treating pigmented lesions. The two colours can be combined to create a greater source of power for ablating or vapourising lesions (there are industrial versions of this laser used for cutting metals).
The two colours also correspond to two absorption peaks in the molecule protoporphyrin IX which is why it has been used in acne treatment (see below).
The recent improvements in the laser have made it more robust but also allowed for better delivery of the light. Initially it was produced as a bare fibre delivery system. This allowed the light to issue directly from the end of the fibre-optic cable. A problem with this is that it tends to become contaminated readily and become charred, reducing the delivery. Some time ago a hand-piece was added that allowed focusing of the light at a specified distance (marked by a guide-wire end on the hand-piece). This allows intense application of power at a point (about 0.6mm) to create strong local changes. It is the piece that is used for ablating lesions like unwanted moles etc.
The contact point hand-piece again focuses light to a point but through a perspex 0.6mm tip. With a gel coating of the skin the light is traced over the lesion. It allows good penetration of the light at the treatment point with minimal surface scatter. It is a good means of treating blood vessels and non-elevated pigmented lesions. It can be used for the free-hand scanning treatment of the face in a photo-rejuvenation mode.
Two other Perspex contact tips are currently available, one with a 2mm point, the other with a 10mm one (an earlier version of it had a 5mm point). The former was designed for treating acne (we also employ it in the treatment of stretch marks). The other, designed for photo-rejuvenation, has a motorised scanning mode that rapidly scans over the area of the 5-10mm point as it is held in place.
Different problems that can be treated
With the dual wavelengths of 511 & 578nm corresponding to two of the absorption peaks for protoporphyrin IX, acne has been treated by the contact 2mm Perspex tip. The theory behind this is, as with blue light treatment, that within the bacteria which are involved with acne lesions molecules of protoporphrin IX are present. When activated by appropriate wavelength lights singlet oxygen radicals are produced which kill the cells. Hence acne activity can be produced.
Because green and yellow lights penetrate deeper than blue, the effect will extend further than with the traditional blue light.
As mentioned under the section on photodynamic therapy, the effectiveness of this treatment is quite limited as it relies on the presence of the particular bacteria. We have trialed this method of acne treatment but find photodynamic therapy much more effective for all levels of acne.
Facial Blood Vessels
The fine telangiectasiae (commonly called spider veins) of the face are quite well treated by the Dual Yellow laser using the 578nm yellow light. There is some “pinging” sensation as this occurs. This is less obvious when the contact tip is employed. As the yellow light has a limited maximum power some vessels are less well managed by the Dual Yellow. These are any vessels that are larger, of high flow and especially those about the sides of the nose. For these, and most face vessel problems, we use the Xeo Cool Glide laser.
Lentigos and Freckles
Over time people who freckle on sun exposure tend to produce larger brown lesions known as lentigos. They are flat, non-raised but due to their size, tend to be quite noticeable. Before treatment they need to be checked to ensure they are benign. Individual lesion treatments or scanning general ones will reduce them.
Unwanted moles can be vapourised leaving a small dark base that will flake off usually in one to three weeks depending on the location. A small pink area will be present for a time. This should gradually merge to normal skin colour. Any lesion that appears suspicious must be biopsied before treatment. Any malignant change should not be treated this way.
Other Pigmented Lesions
Excluding malignant lesions, a wide range of other pigmentation problems can be treated. Those that occur deeper in the skin structure usually require another approach.
This has become very popular in recent years. From the mid 1990s the CO2 laser was widely used in an ablative (vapourising) fashion to improve sun-damaged skin. Exposure to the sun creates faster ageing changes in our skin. We produce less collagen and elastin. Fine lines and wrinkles result. Our surface cells multiply more slowly with resultant skin thinning. The very top cells become more flattened and keratinised (crusty). As a result the translucent nature of our skin reduces. Patchy pigmentation and fine blood vessels appear.
By removing all the old skin from our face, new fresher skin appeared, wrinkles decreased and colour was more even. But there was some downtime involved as the skin regenerated. The open graze took some time to heal and was subject to the side effects of infection, scarring and permanent pigmentation loss.
Advances in the CO2 laser helped but did not eliminate problems. The Erbium laser was less troublesome this way but still involved downtime. Also because of the less rapid turnover of other skin, the face was about the only area of the body which could be treated in this way.
We have covered some of these ideas and other ways of treating this problem in our non-ablative laser treatments with the Xeo Cool Glide laser.
Throughout the world Intense Pulsed Light devices have been employed to achieve some non-abative changes. Usually quite a few sessions are required, they can be painful, and there are significant variations between machines and operators.
The Dual Yellow can be employed with a free-hand scanning contact motion, or the programmed scanner, to produce dramatic changes with only one or two sessions. The best results are in Caucasian skins with pigmentation and redness problems. Some wrinkle reduction will result. But this will be greater with more sessions. Dark areas will temporarily become darker, but then shed, leaving more youthful even-coloured skin.
These non-malignant variously raised and pigmented lesions seem to have a hereditary basis and occur later in life. We produce more as we age. Their colour can vary from pale skin to almost dark black. If rubbed, they can become bigger. They can also be scratched off leaving a bleeding base. They will then reoccur at the same point.
Using the non-contact tip and usually the combined energies they can be ablated to a flat dark mark that will gradually flake off leaving a slightly pink base that will assume normal skin colour over time.
Redness in early scars can be rapidly reduced with a couple of point and contact scanning sessions with the Dual Yellow laser using the yellow light. Further sessions, using the scanning mode with yellow 578nm light will cause quite significant remodelling of the scar. There will be some residual mark evident. But the appearance will be greatly lessened.
These appear as red to whitish scaling rough lesions on sun-exposed areas of the body, especially the hands and the face. Over quite a few years some of them will turn to skin cancers. By treating them with 578nm yellow light in an ablative fashion (but sometimes with contact one) they can be removed with very little disturbance to the underlying and surrounding skin. This is especially when compared to the standard liquid nitrogen cryotherapy. However the laser treatment is much more expensive.
We find the new Metvix photodynamic therapy much more straightforward and effective.
Our best results for stretch marks have occurred with the Dual Yellow laser. Using the yellow light in contact mode (we usually use the 2mm contact head) we trace over and around the marks at sessions usually three or four weeks apart. One or two sessions can dramatically reduce redness of the marks.
For further changes to the appearance, usually five or six sessions are required. Some can reappear a while later, but can then be treated again. Care needs to be taken with darker skin types to avoid hyper-pigmentation.
Wrinkles and Lines
As noted in the photo-rejuvenation section, fine lines and wrinkles tend to reduce with scanning treatments. Changes can be noticed with one treatment. But several are needed for more dramatic results. Finer skin lines about the eyes show change more rapidly. Care needs to be taken about the eyes to not affect sight.
Melasma (Blotchy Pigment)
A new protocol involving around four treatments with the dual yellow laser has been developed through studies in Korea. This can result in a long term clearing of this vexing problem.
For Further Information On Dual Yellow
See the site for Norseld, the manufacturer of the laser.