Feature: Taking a Closer Look at Post-Surgical Skin Changes - By Larisa Hubbs, Executive Editor Researchers share their experiences using a variety of advanced technological devices to objectively measure the effectiveness of ablative vs. non-ablative laser treatments on photodamaged skin. A n ongoing controversy in cosmetic dermatology has been how to tell if patients’ wrinkles improved — and by how much — following laser surgery, especially when patients have undergone the kindler, gentler version of laser resurfacing — non-ablative laser treatment. As you know, changes can be so subtle that critics — and physicians who perform the procedures — claim they want proof of improvement. This has led to a growing momentum among dermatologic surgeons to discover the best ways to objectively measure improvements to skin following laser surgery. “One of the things we’re seeing in the dermatologic surgery specialty is the desire and ability to quantify improvements in laser surgery outcomes,” explains Roy Geronemus, M.D., director of the Laser & Skin Surgery Center of New York and immediate past president of the American Society for Dermatologic Surgery. “Doctors want ways to measure improvements in fine lines, rather than just stating ‘the patient looks better,” he adds. To quantify outcomes in an objective manner, Dr. Geronemus and other physicians at the Laser & Skin Surgery Center of New York teamed up with Stacy Hawkins, Ph.D., a senior research scientist at Unilever Research and Development, and a team of scientists to evaluate two groups of patients who had undergone either ablative or non-ablative laser treatment for their photodamaged skin. While a few other studies have used some of the technologies used by the researchers in the study detailed here, there hasn’t been a study that has used this large a number of quantitative measuring devices to evaluate the same patients. “This study covers the state-of-the-art in technology in terms of devices we could use to objectively measure outcomes,” explains Dr. Geronemus, who was one of the lead researchers on the study. One of the main reasons the researchers used so many types of technologies was not only to objectively quantify outcomes but also to establish mechanisms of quantification for future studies, according to Dr. Geronemus. Here, read and view some of the interesting results the researchers attained after studying approximately 25 patients. A Look at the Patients • The ablative laser resurfacing group. Five patients underwent ablative laser resurfacing. Their ages ranged from 40 to 55, and the researchers used an Ultra Pulse CO2 laser to perform laser resurfacing of facial photodamaged skin. The subjects in the ablative laser resurfacing group received one treatment and were followed for 6 months post-treatment. • The non-ablative laser subsurfacing group. Twenty patients underwent non-ablative laser subsurfacing treatments. Their ages ranged from 40 to 55, and the researchers used a Cool Touch II system. The subjects in the non-ablative laser subsurfacing group underwent five treatments and were followed for 3 months post-treatment. Patients in both treatment groups had a moderate degree of photodamage. Rundown on the Technology Five different types of technology were used during the study to measure skin structure, skin firmness, skin elasticity and skin texture. Here’s a closer look at the devices the researchers used: • Optical Coherence Tomogra-phy (OCT). Researchers used a standard OCT device to measure the epidermal thickness. This technology utilizes a light source, which is projected through fibers that scan a light beam across the tissue that’s being imaged. Light is backscattered, and the result is a two-dimensional image that’s far more detailed and accurate than what is produced with currently available high-frequency ultrasound systems. • BTC-2000 (SRLI Technologies). This device non-invasively provides measurements of the skin’s elasticity to track wound healing and repair. The device employs a laser to obtain in vivo biomechanical measurements of the skin. The device creates a vacuum pressure that gradually and safely stretches and then releases the skin. The skin’s elastic compliance to stretch, firmness and elastic return of the skin after pressure is removed may then be measured. • Torsional Ballistometer (Dia-Stron Limited). Using a pendulum, which is dropped on the skin in order to create an impact on the skin’s surface, this device determines the level of indentation in the skin to gauge skin firmness. • DigiSize 3-D software (Cyber-ware). To measure skin texture, this near infrared laser-based system was used to obtain full-facial scans before and after treatment. The multi-point laser scanner computes numerous facial measurements in about 15 seconds without the need for any skin contact. The depth, volume and length of facial rhytids may then be measured to accurately characterize improvement. This technology is already being used in the film industry for film special effects, for reconstructive and cosmetic surgery, in the garment industry to ensure exact-fitting clothing and in designing ergonomically friendly products. (See above image for details.) • PRIMOS (GFMesstechnik). Researchers used this optical 3-D profiling system to also measure skin texture. This technology utilizes a projection device that projects a parallel series of digital stripes onto the skin. Then, a special camera (a CCD camera) records the stripes on the skin’s surface, and the information is processed by the CCD chip in the camera to provide a 3-D image of minute differences in elevations in the skin. What the Technology Revealed After using the OCT to measure epidermal thickness, researchers noted the greatest improvements in patients who underwent the ablative therapy, explains Dr. Hawkins. Note the changes in epidermal thickness in one of the patients who underwent ablative laser resurfacing. The differences are represented by looking between the red arrows at baseline and 6 months post-op. Improvement in epidermal thickness seen in the non-ablative treatment group was relatively much smaller than in the ablative treatment group. With the BTC-2000, researchers noted improved elasticity with the non-ablative patients when they measured the amount that the skin could distend and snap back. Patients who underwent ablative laser resurfacing still exhibited skin stiffness, which was most likely due to improved firmness with dermal remodeling in addition to the continuation of wound repair by the study’s end, says Dr. Hawkins. The results of skin firmness that were attained with the Torsional Ballistometer are represented in the graph on page 101. In the graph, the starting height of the pendulum drop is represented by line A (far left in image), B represents the depth of indentation, and C shows the different rebound heights. In the main image, comparing results from ablative and non-ablative patients, you can see that both the non-ablative and the ablative patients achieved significant improvement in firmness by resistance — their skin doesn’t have great indentations and is more supportive. As mentioned before, the Cyberware 3-D software was used to obtain full facial scans. This technique that’s been used in the film industry to scan cast extras and also in archeology for creating a virtual museum where someone can scan an object, rotate it, and look at it from different angles, according to Dr. Hawkins. “This technology is very useful for evaluation and analysis because you can have an expert process the before-and-after images at the same time, correctly aligned to baseline positioning and calibrated lighting conditions,” she says. “Using the Cyberware system, we could track the fine textural changes that you would see with improvement to photodamage,” describes Dr. Hawkins. In the image above, you can see the deepest line coming horizontally from the corner of the eye (bottom left of image). Researchers measured significant improvement in this facial area in both treatment groups — a 10% reduction with non-ablative patients 3 months post-treatment, and a 22% reduction in patients who underwent ablative treatment at 6 months post-treatment. The degree of improvement measured with both treatments to the corner of the eye area was similar when measured 3 to 4 months post-treatment. In addition, researchers also found improvement in the volume to the nasolabial fold, explains Dr. Hawkins. “We saw a much larger change with the ablative group, but what we don’t know is if the non-ablative patients would continue to improve over time,” she adds. Finally, researchers noted a reduction in wrinkle density with the PRIMOS imaging system (see image at left to view results in a patient who underwent non-ablative laser treatment). Note how in the before image the fine lines are much more apparent. In the after photo (above right), the lines have definitely filled in noticeably. The yellow topography images show how the surface of the skin has improved. The Overall Results The researchers found that the objective instrumental measurements demonstrated improvement in firmness, rhytids and repair for patients who underwent ablative and non-ablative laser treatment. Not surprisingly, greater changes were noted in patients who underwent ablative laser therapy. “The results were pretty much what we thought we’d see,” comments Dr. Geronemus. However, he adds that the value of the study was not so much in the results between ablative and non-ablative surgery but rather that the tools used to provide objective measurements of the surgical outcomes proved to be so useful. “We’ve received a lot of positive feedback from physicians. They really want some means to objectively assess their work,” he says. Skin & Aging - ISSN: 1096-0120 - Volume 11 - Issue 10 - October 2003 - Pages: 100 - 104