Considering the Utility of Multiple Light Sources and RFID
Panelists weigh in on expanded field of view and radio-frequency identification.
Dr. Packo: In my opinion, one disadvantage of first-generation vitreoretinal surgery technology was the quality of the lighting. How has the lighting evolved?
Dr. Murray: We cannot overemphasize the importance of being able to visualize the tissues that we are manipulating and cutting. The largest single component of that is lighting. I remember how we would put in our 20-gauge light and pray for the best. We would torque the eye out, have a small cone of illumination, very hot focused light sources in the area of illumination and very little illumination outside of the field. Now, I use either 1 or 2 light sources for direct illumination of the field of view and indirect illumination of the surrounding tissues.
Dr. Packo: There have been recent advances in lighting. For example, fully configured, the Constellation system provides two light sources with four ports of illumination. Do we really need four?
Dr. Murray: I am often in situations where I routinely use three. In 20-gauge surgery, I like to use a 20-gauge infusion chandelier that gives me a wide illumination source. I like to have a light source in the eye, and during laser, I like an illuminated laser probe that allows me to directly visualize the field. Having a backup is also a good idea, so we do not have to change the pace of our surgery if a light source malfunctions.
RFID FOR ILLUMINATION
Dr. Murray: The integration of radio frequency identification (RFID) technology into a vitrectomy system is a significant safety enhancement. It allows us to configure the illumination out of the port to the probe and avoid the potential for toxicity.
Dr. Packo: In the Constellation system, can we use a probe from a third-party vendor that does not have the RFID chip?
Dr. Murray: Yes, but you must manually select the parameters of your lighting source, eliminating some of the safety benefits of RFID technology, namely the interface of having a prepopulated lighting parameter setting.
Dr. Packo: With a probe from a third-party vendor, you must choose a similar probe, and the major governor is the fiber size. So if you tell the machine you are using a 20-gauge fiber, the machine limits the light level to a certain point. If you want higher light levels, you have to "fool" the machine by selecting smaller fibers. When you select a 25-gauge probe, it opens up the full capability of the xenon light.
Dr. Murray: Being able to look at the light levels directly is important, and we have not been able to do that. We have used our probes at high 1, high 2, high 3, or 100%, 80% or 50%, but to get a better idea of what illumination is coming out of the probe and to understand the impact will be important. We want to enhance the safety of surgical procedures for our patients, and this is one area that is significant.
COLOR TEMPERATURE CONSIDERATIONS
Dr. Packo: We have become accustomed to viewing the eye with the slightly blue-tinged xenon light, moving from the more yellow-tinged halogen. Some manufacturers are interested in going to metal halide, which gives a different color spectrum. Did you notice any difference in the color spectrum in the various xenon systems?
Dr. Dugel: We want to be able to see the pigmented structures, particularly the RPE or blood, and that is easily seen as long as the light output is normalized, which is done automatically. The color temperature of the various xenon systems are similar. What we want is a reliable system that maximizes the light transmission to the fiber. RP