Japanese researchers have identified a way of making the procedure oesophagogastroduodenoscopy (EGD), which is used to examine the lining of the esophagus, stomach, and upper duodenum, less painful.

EGD involves the insertion of a small flexible camera down the throat. While the administration of sedative drugs prior to the procedure is effective in relieving pain, such drugs can have significant side effects.

Dr Kazuhide Higuchi, from Osaka City University, and colleagues therefore looked at slow-wave photic stimulation as an alternative way to deliver pain relief to patients undergoing EGD.

Slow-wave photic stimulation has previously been shown to be effective in therapy for mental stress, depression and headaches. The technique involves the patient wearing special goggles connected to a light signal generator, which delivers stimulation to the patients' closed eyes during EGD and for a few minutes after the procedure.

The researchers found that 20 patients who underwent EGD with light stimulation for 25 minutes felt less discomfort than 20 patients who underwent the procedure without light stimulation.

Moreover, relative to previous examinations, 18 individuals in the photic stimulation group showed improved pain and discomfort scores, compared with just three of those not receiving photic stimulation.

"This study demonstrates, for the first time, that photic stimulation of slow-wave activity relieves the discomfort/pain caused by EGD," Dr Higuchi and colleagues write in the Journal of Gastroenterology and Hepatology.

"These findings suggest that photic stimulation might be a useful, easy and safe technique to improve patient tolerance without medication during screening EGD," they speculate.