Jim Happell, Ph.D., could write a dissertation on sulfur hexafluoride in his sleep. For the past 15 years, the University of Miami scientist has measured the presence of the colorless, odorless, and nonflammable gas in oceans around the world, using it as a transient tracer to study currents and circulation patterns.
“It’s like pouring dye into water, actually,” explained Dr. Happell, a research associate professor of ocean sciences at UM’s Rosenstiel School of Marine and Atmospheric Science. “Small amounts of sulfur hexafluoride that are in the atmosphere eventually dissolve into the surface of the ocean, where it essentially acts like a colored dye, allowing us to trace it and watch it move into the deep ocean. That helps us get all sorts of information on flow patterns.”
But what Dr. Happell never anticipated is that the gas, known by its chemical formula SF6, would help in another endeavor — a surgical procedure that probably prevented him from going blind in one eye.
Two weeks before he was to depart on a research cruise to the Pacific, Dr. Happell began experiencing symptoms of obscured vision that he could only describe as a veil or curtain being drawn across the corner of his right eye. After a thorough exam at Bascom Palmer Eye Institute at UM’s Miller School of Medicine, an ophthalmologist gave him the bad news: He was suffering from a detached retina initiated by a posterior vitreous detachment (PVD).
A natural change that occurs as one ages, a PVD is a condition in which the vitreous gel that fills the eye separates from the retina, the light-sensitive layer of tissue in the back of the eye that helps you focus on the images you see. Many people never experience symptoms and may never know they have one. But in other cases, a PVD can cause retinal tears.
“That’s exactly what happened to me,” said Dr. Happell.
His ophthalmologist repaired the damage that same day, sealing the retinal tear with a laser and using a gas bubble of SF6 to reattach his retina.
“SF6 just happens to be a gas that has properties that make it somewhat inert, and it has solubility properties that allow it to remain in the eye for a specific period of time when used in the right mixture,” said William E. Smiddy, M.D., a retina and vitreous diseases specialist who is the M. Brenn Green Chair in Ophthalmology at Bascom Palmer. “But it’s the physical more than the chemical properties that lend the SF6 to what we really use it for.”
Dr. Happell was astonished when he learned the gas, an excellent electrical insulator often used in power transformers, would be injected into his eye to help reattach his retina.
“I kind of chuckled and said, ‘Isn’t that ironic — that’s one of the gases I measure when I go out to sea,’” Dr. Happell said. “There were several other doctors and medical students in the room. I had already explained that I was an ocean scientist, so everybody there got a brief oceanography lesson.”
The vision in Dr. Happell’s right eye is now much better. He wasn’t able to go on his research cruise, but he will pick up the second leg of the expedition later this month in Hilo, Hawaii. He’ll spend 30 days in the Pacific studying ocean currents by measuring — what else — sulfur hexafluoride.