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Ultra-rapid cooling of eye may provide effective nonpharmacologic anesthesia
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VANCOUVER, British Columbia — The first-in-human feasibility trial comparing nonpharmacologic, ultra-rapid focal cooling and standard-of-care pharmacological anesthesia showed the novel method was quicker, was well-tolerated by patients and resulted in similar patient-reported pain scores, according to a speaker here.
“Ultra-rapid cooling of the eye was well-tolerated and provided effective nonpharmacologic anesthesia. This first-in-human proof-of-concept study indicates that ultra-rapid cooling may be useful for ocular anesthesia, and we believe that this novel method may be an improved way of delivering anesthesia and improve patient care of intravitreal delivery,” Cagri G. Besirli, MD, PhD, said at the American Society of Retina Specialists annual meeting.
The current methods of ocular anesthesia have a variety of drawbacks, including patient risk for corneal toxicity and subconjunctival hemorrhage. Additionally, surgeons must wait between 3 and 10 minutes for the anesthesia to take adequate effect, Besirli said.
Besirli and colleagues created a focal cooling device to provide patients with ocular anesthesia.
“You put the device about 3 mm to 4 mm from the limbus ... activate the cooling and the cold temperatures rapidly penetrate the deep tissue, block the nerve conduction, and once you have this within 10 to 20 seconds, you perform intravitreal injection using standard technique,” he said.
To test the feasibility and efficacy of the technique, 22 patients were included in a single-center, randomized, unmasked, controlled trial comparing focal cooling and standard-of-care pharmacologic anesthesia. Patients were randomly assigned to one of five cooling groups, ranging from –5°C for 10 seconds to –10°C for 20 seconds. The second eye of each patient underwent the standard of care.
“We found that the effect of the pain control was better in increasing treatment duration and decreasing temperatures,” Besirli said.
Patients in the –10°C for 10 seconds and –10°C for 20 seconds groups reported similar pain scores as patients who received traditional anesthesia. Also, ultra-rapid anesthesia via cooling reduced patient wait times for intravitreal delivery, about a 4.5-minute savings when compared with the standard of care.
Additionally, at 4 hours after injection, pain scores were similar between the target temperature of –10°C and the standard of care, Besirli said. – by Robert Linnehan
Reference:
Besirli C. Clinical feasibility of ultra-rapid, non-pharmacologic anesthesia for intravitreal injection in patients receiving anti-VEGF treatment. Presented at: American Society of Retina Specialists annual meeting; July 20-25, 2018; Vancouver, British Columbia.
Disclosure: Besirli reports he receives equity and consulting fees from iRenix Medical.