Alternative disinfectant suggested for intravitreal injections

SAN ANTONIO, Texas – Hypochlorous acid causes less pain than povidone iodine when used as a disinfectant before intravitreal injections, researchers say.

Povidone iodine is the standard of care, but hypochlorous acid may offer a viable alternative, at least in patients who find povidone iodine unbearable, said Robert L. Avery, MD, of California Retina Consultants in Santa Barbara, in. California, who presented the discovery at the 2021 annual meeting of the American Society of Retina Specialists (ASRS).

“There is no doubt that it is less painful,” he said Medscape Medical News. “The only question is whether it does the job too.”

To compare the two treatments, Avery and his colleagues recruited 62 patients and treated one eye in each patient with hypochlorous acid and the other eye with povidone iodine.

After instilling the disinfectant, the researchers asked the patients to rate their pain on a scale of 1 to 10, with 10 being the worst pain the patients had ever felt. The researchers repeated the question immediately after the injection and 1 to 2 hours after the injection.

Table. Disinfectant pain


After disinfectant, scale 1-10

Immediately after injection, scale 1-10

1-2 hours after injection, scale 1-10

Povidone iodine




Hypochlorous acid




P value


An hour or two after the procedure, 51 of the patients reported that the eye treated with hypochlorous acid was more comfortable than the eye treated with povidone iodine. None said the eye treated with povidone iodine felt better, while eight said there was no difference and three did not respond. Thirty-nine reported a foreign body sensation in their eye with povidone iodine, compared with three who said the same about their eye with hypochlorous acid.

The proportion of negative cultures was 68% with povidone iodine and 47% with hypochlorous acid. The difference was not statistically significant (P = .067), and none of the patients had endophthalmitis, but the trend towards more negative cultures with povidone iodine raises concerns about hypochlorous acid, Avery said.

Previous studies have shown better disinfectant results with increased application of povidone iodine drops; the same could be true of hypochlorous acid, Avery said. When using it in his own office for patients who cannot tolerate povidone iodine, Avery applies hypochlorous acid up to five times before and after applying an anesthetic gel.

A randomized controlled trial is underway to provide a more definitive comparison of the two disinfectants, Avery said.

Hypochlorous acid is an important potential addition to the therapeutic arsenal for infection control in intravitreal injections, said Linda Lam, MD, MBA, professor of ophthalmology at the University of Southern California Roski Eye Institute in Arcadia. . “This is the aspect of the procedure that patients are most unhappy with,” she said. Medscape Medical News .

Like Avery, she would need to see more research before using hypochlorous acid on a regular basis. But she said it might be helpful in patients who don’t want to be treated again after getting a povidone iodine injection. “There are a lot of patients who just don’t come back,” she said.

The study was funded by the California Retina Research Foundation. Avery said he has been a consultant for companies making drugs for intravitreal injection. Lam did not disclose any relevant financial relationship.

American Society of Retinal Specialists: Comparison of the use of hypochlorous acid versus povidone iodine before intravitreal injection: a prospective randomized trial (PAVE study). Presented October 9, 2021.

Laird Harrison writes on science, health and culture. His work has been featured in national magazines, newspapers, public radio, and websites. He is working on a novel on alternative realities in physics. Harrison teaches writing at Writers Grotto. Visit him on or follow him on Twitter: @LairdH.

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