Combo Anesthesia During Retinal Laser Treatment Reduced Pain Perception

Combined topical and subconjunctival anesthesia reduced pain perception and treatment interruptions in diabetes patients undergoing panretinal photocoagulation (PRP) compared with topical anesthesia alone, according to a small retrospective observational study.

Patients' pain perception was significantly lower in the combination group -- 5 points versus 9 points on the pain grading scale (P<0.0001) -- while PRP was stopped for pain a mean number of 12.5 times for about 30 to 60 seconds with topical anesthesia versus 6.7 times with the combined anesthesia (P<0.0001), reported Marco Mafrici, MD, of Alès-Cévennes Hospital in France, and colleagues in the European Journal of Ophthalmology.

"Retinal laser therapy can sometimes reach a level of discomfort that some patients find unbearable, so it becomes necessary to pause the treatment on multiple occasions," Mafrici told MedPage Today. "We recognized the need for anesthesia to reach deeper into the posterior area."

The result was an anesthetic technique specifically developed for diabetic retinopathy therapy that went beyond providing the surface numbness of standard topical eyedrops.

In five eyes given only topical anesthesia, laser treatment was stopped owing to pain and discomfort, with no complications. Five eyes in the combination group presented with a small subconjunctival hemorrhage that was reabsorbed after a few days.

"This research has significant value as it underscores the importance of prioritizing the patient's comfort," Mafrici said.

The mean number of laser spots was significantly higher with combined anesthesia at +84.2 spots (P=0.01), with reduced time for laser execution (-2.5 minutes, P=0.0008). The mean number of anesthetic instillations in a single session was significantly reduced in the combination group (6.7 times vs 12.5 times).

With topical-only anesthesia, both the number of laser spots in a single session (r=0.50, P=0.02) and the duration of treatment (r=0.45, P=0.04) were associated with increasing patient age. No similar associations with spot numbers (r=0.21, P=0.36) and duration (r=-0.31, P=0.18) emerged under combined anesthesia.

"It is encouraging to see that there is continued interest in addressing this persistent problem in the current performance of PRP in the clinical setting," said Sam E. Mansour, MD, MSc, of the Virginia Retina Center in Warrenton, Virginia, who was not involved in the study. "Pain control for this procedure is currently under-managed."

He told MedPage Today that in the U.S., dual ocular anesthesia in this patient population is rare, with more than 80% given topical anesthesia alone, according to a recent survey by the American Society of Retina Specialists.

Despite the growing use of anti-vascular endothelial growth factor drugs for diabetic retinopathy, conventional PRP is still widely used in severe stages of the disease, Mafrici and colleagues noted. This procedure is painful, however, involving the burning of ischemic areas of the retina to prevent them from releasing pro-inflammatory cytokines and growth factors and triggering new abnormal vessels.

To date, few studies have investigated pain perception in diabetic patients during PRP laser treatment, the authors added, with research largely focused on comparing the efficiency and safety of different laser devices and the effectiveness of new laser technologies.

They acknowledged that the subconjunctival technique is more invasive, with adverse effects related to injection and potential drug-related consequences. "However, in a single session, the same patients completed laser photocoagulation in the fellow eye under combined anesthesia," they wrote.

"There needs to be a balance between adequately providing anesthesia during PRP and minimizing risk from more invasive techniques," said Mansour. "We know that retrobulbar anesthetic injections, for example, carry the greatest risk of complications, such as retrobulbar hemorrhage, penetration of the globe, and optic nerve damage."

The hope, the authors noted, is to make diabetic retinopathy treatment a painless procedure. "It would be intriguing to explore novel pharmaceuticals or innovative devices aimed at enhancing the patient's pain tolerance," Mafrici said. "We hope our research can lead to more comfortable experiences for both patients and healthcare providers during PRP."

For this study, the researchers consecutively enrolled 21 treatment-naive patients with type 1 and type 2 diabetes mellitus and severe, proliferative bilateral diabetic retinopathy. Mean age was 58.3; 13 were men.

Before PRP, one eye was treated with topical oxybuprocaine hydrochloride drops alone. In cases of severe pain, the fellow eye received topical anesthesia in combination with 2% subconjunctival lidocaine. The groups were compared for pain perception using an analog visual scale, number of laser spots, number of interruptions, and laser session duration.

Study limitations included the small sample size, the retrospective design lacking randomization and blinding, and the subjective nature of patient-reported pain perception, laser tolerance, and discomfort.

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