Laser-based light source

  A laser light source may be the next step in the evolution of illumination systems for vitreoretinal surgery, because it provides brighter and safer illumination, tunable colour and microfibre capability, said Carl C Awh MD at the 16th EURETINA Congress in Copenhagen, Denmark. Being introduced by Katalyst Surgical, LLC, the new technology uses three lasers emitting 450nm blue light, 520nm green light, and 638nm red light that can be combined to create virtually any colour. “Conventional adjustment of light colour by coloured filters results in reduced brightness because the filters subtract light by absorption, resulting in a coloured light much less intense than the original white light. In contrast, colour tuning with the laser source occurs by light addition, with no loss of intensity. We are now able to create virtually any colour by combining different proportions of the three light colours,” said Dr Awh, who is in private practice with Tennessee Retina, Nashville, USA. Higher power density is another important benefit of the laser light source, because power density is a major limiter of the diameter of optical fibre through which light can be effectively transmitted. The laser light source is capable of projecting light through optical fibres that are much smaller in diameter than those used with current xenon, mercury-vapour, and LED technology. OPTICAL FIBRE With the latter conventional light sources, 15 to 40 lumens of light can be delivered through optical fibres that range in diameter between 250μm and 750μm. A 250μm optical fibre, which can fit within a 27-gauge instrument, transmits a maximum 20 lumens of light if connected to a conventional light source. In contrast, the laser light source can deliver the same 20 lumens of light through a 50μm fibre and 30 lumens of light through a 100μm fibre, Dr Awh explained. “This could lead to a new generation of illuminated multi-function devices. As an example, with the laser light source we can create illuminated infusion lines that provide useful light without loss of flow. Using new tubular fibre optics, we may also be able to create lighted cannulas or vitrectomy cutters. The increased brightness of the laser light should now make it possible to create a variable field illuminator that delivers both focal and wide-field illumination,” he said. Using videos, Dr Awh demonstrated the increased light intensity provided by the laser source and its benefits for improving intraocular visibility. He also showed how the appearance of different tissues and pathologies could be enhanced by tuning the light colour. Highlighting another advantage of colour tunability, Dr Awh noted that the ability to eliminate blue wavelengths of light could virtually eliminate the risk of retinal phototoxicity. Dr Awh concluded that continued development of the laser light source bring surgeons the advantages of brighter safer light, tunable colour, and microfibre capability. Carl C Awh: carlawh@gmail.com

Tags: cornea, laser