A careful use of technique, power parameters, and preventive moves against IOP spikes can make cyclophotocoagulation or phaco and ECP more effective.
Reviewed by Jeffrey Kammer, MD
Close attention to details when performing transscleral cyclophotocoagulation (CPC) or phacoemulsification with endocyclophotocoagulation can go a long way in preventing complications and ensuring excellent results, according to Jeffrey Kammer, MD, associate professor of ophthalmology, Vanderbilt Eye Institute, Nashville, TN.
With transscleral cyclophotocoagulation, the most vision-threatening complications include hypotony, phthisis, and vision loss. The first step to help avoid these is to carefully select the surgical location. “If you can avoid the 3 and 9 o’clock locations, you are less likely to cause ischemia and its associated complications,” Dr. Kammer said.
“Surgeons also should titrate their power appropriately. “When using the classic CPC treatment parameters, I prefer to start at a lower power, titrate up just a little until you hear a little crackle, and then decrease the power to just underneath that level,” Dr. Kammer said.
Avoid the ‘pop’
Dr. Kammer tries to avoid hearing a loud “pop” because this is indicative of tissue destruction. In these cases, he typically starts with a power between 1,750 to 2,250 mW (higher watts in patients with lighter pigmentation and lower watts in patients who are more heavily pigmented), with a duration of 2,000 mS and six spots per quadrant. Surgeons also may want to consider the use of the alternative Gaasterland “slow coagulation technique” that was popularized by glaucoma specialist Doug Gaasterland, MD.
In this treatment paradigm, patients are treated with lower energy per pulse but with longer treatment duration. Patients typically experience less pain, less inflammation, and less macular edema, albeit with similar efficacy compared to the traditional CPC treatment paradigm, according to Dr. Kammer. Dr. Kammer also stressed that cyclophotocoaguation should not be relegated to endstage glaucoma.
In fact, he noted that transscleral CPC is highly effective with a more favorable side effect profile in patients with mild-to-moderate glaucoma. This has been noted in traditional transscleral cyclophotocoagulation laser therapy as well as with the newer Micopulse cyclophotocoagulation.
Embracing the use of newer techniques, (Micropulse Cyclophotocoagulation, Iridex) offers a less destructive laser modality that provides excellent efficacy with a more tolerable side effect profile. In fact, due to the fact that this technique does not actually coagulate the underlying tissue, Dr. Kammer prefers to call this Micropulse Cyclo “modification.” In “modification” technology, a continuous-wave of energy is released in a series of repetitive short pulses. This allows the underlying tissue to be heated up and altered without actually destroying it.
Dr. Kammer also shared a Micropulse cyclophotocoagulation technique-related pearl, recommending that surgeons’ probe axis be placed roughly 1 mm behind the limbus and perpendicular to the sclera. This is in contrast to classic transscleral cyclophotocoagulation, where you hold the Gprobe immediately behind the limbus and parallel to the visual axis, he said.
Jeffrey Kammer, MD
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This article was adapted from Dr. Kammer’s presentation at the 2019 American Glaucoma Society annual meeting. Dr. Kammer is a consultant for Iridex.