Retina Today - First Impressions of the Iridex IQ 577 Yellow Laser: Seeing Is Believing (April 2010)

摘要

As we all are aware, diabetic macular edema (DME) is the cause of mild to moderate vision loss in about 40% of patients who have diabetes, so it is a formidable problem for us to manage. In the 1980s, we based our treatment for DME on contact lens examination. In those days, thickness was thickness, and there was no real distinction in terms of different types. Today, we have the benefit of better imaging technology that shows more detail within the retina, so we can decide which eyes may be more appropriate for a particular treatment. The ETDRS study1 showed a reduction in vision loss with standard grid laser therapy, and patients were grateful, but most patients today hold us to a higher standard. My patients ask, a??When am I going to see better, doctor?a?? Answering that can be a challenge, because often they have systemic issues that are difficult to manage. In general, the benefits of laser photocoagulation include reduced retinal thickening and some slight visual improvement, but we are still grappling with the problem of thermal injury. The impact of inducing scotoma is sizable, particularly as it affects a patienta??s ability to read. Most patients do not experience appreciable visual acuity improvement In recent years, researchers have investigated pharmacologic remedies, but the data have shown laser photocoagulation is still better for our patients with macular edema.2,3 Laser is our gold standard, and in terms of overall management, I think it will continue as such for some time. The question remains: How do we optimize laser therapy to enhance visual and anatomic results and minimize patient discomfort? POLISHING THE GOLD STANDARDWhen Iridex introduced the IQ 577 yellow laser, I saw that it had some interesting clinical advantages. Visibility at the slit lamp is better with the yellow laser. Because 577 nm is at the peak absorption of oxyhemoglobin, the IQ 577 produces consistently sharp burns. Blanching occurs with lower power settings and is confined to a smaller area due to the reduced scatter of the laser. In terms of panretinal photocoagulation, the 577 nm yellow causes less pain because it uses less energy than either 532 nm or 561 nm systems.A notable feature of the IQ 577 is its ability to turn off the red aiming beam while the footswitch is depressed. This is important because the surgeona??s eyes tend to fatigue, looking at the bright laser, even when the aiming beam is turned down as much as possible. With the aiming beam turned off, you can easily distinguish early burn development. APPLYING THE a??RESIDENTS TESTa??What I particularly like about the IQ 577 and find useful for residents is that the eye safety filter system allows the simultaneous use of a red-free filter on the slit lamp while treating. As we know, the red-free accentuates the visibility of xanthophyll pigment so the surgeon can clearly see the fovea and the parafoveal region. We can see what we should be treating from the fluorescein, but we cannot necessarily distinguish it clinically, especially when viewing a fundus image. Trying to decide where or how close to the macula to treat can be difficult. The red-free filter distinguishes the macular pigment and highlights any microaneurysms. The surgeon commonly will not treat with red-free light when using a green laser because it is somewhat disorienting, and visualization is compromised. With a green (532 nm) system, the protective filter blocks the green light coming from the slit lamp. It can be difficult to have the light bright enough to see without creating additional discomfort for the patient. With the IQ 577, however, we can comfortably see the target area because the filter blocks the yellow (577 nm) lighta??not the green light I like to test certain theories with my residents because they do not have intellectual baggage from years in practice. I tell them, a??Ia??m going to let you treat these areas, bu