Letter to the Editors

We appreciate the comments by Dr Cyrus Chess regarding our clinical comparison of hair reduction using the newest generation IPL and a Ž rst generation ruby laser. Dr Chess suggests that similar parameters regarding spot size, pulse duration, and contact between irradiator and skin should have been used. However, a standardization of these parameters would have totally changed the scope of the investigation, which was to perform a clinical comparison of one of the earliest, to one of the newest, devices for hair removal. In other words, our aim was to investigate the clinical implications of the technological developments of a couple of treatment devices since the beginning of optical depilation. It is beyond the scope of the present investigation to study the clinical effect of every single speciŽ c difference in the physical parameters of the two devices. We agree with Dr Chess in his general comments on spot size, pulse duration, and photon recycling. Instead of comparing the Ž rst generation ruby laser to the IPL, we could have chosen to compare the Ž rst ruby laser with one of the newer ruby lasers. However, to make the investigation more relevant to the majority of current users of optical depilation devices, we decided to compare the ruby laser to an IPL, as the IPLs have gained increased popularity in recent years. A comparison between the E-2000 ruby laser and the Ellipse Relaxlight 1000 as suggested by Dr Chess was not possible, as the E-2000 was not available at the beginning of the study. It was not our intention to state that broad band irradiation in general is more effective than monochromatic light. We investigated the clinical efŽ cacy of two speciŽ c devices and found the new IPL to be more effective than the ruby laser, and we did not attempt to draw any general conclusions regarding the efŽ cacy of other devices.