Silicone hydrogel lenses appear to produce more mucin balls.

Presence of mucin balls more of a menace than thought

Excerpted from page 54 of the July/August 2017 edition of AOA Focus.

According to recent research, mucin ball formation can increase the risk of corneal in­filtrative events.

Interestingly, the study clari­fies research from a decade ago that seemed to indicate that mucin balls-spheres formed by a principal component of mucus-afforded a degree of protection over the eye. This new information warns clinicians that an entity previously thought to be benign can present a real danger to patients.

"If you see mucin balls, think twice about the type of lens that patient is wearing."

Researchers found that patients who were shown to be mucin ball producers experienced a greater rate of corneal in­filtrative events when using a very stiff extended-wear contact lens. The type of lens that seemed to produce more mucin balls was made out of silicone hydrogel. Almost 70 percent of all lenses sold today are made out of silicone hydrogel.

"In a corneal in­filtrative event, there is some type of bacteria or pathogen that triggers antigen-presenting cells to mount an in­filtrative response. That means they trigger the eye to send in white blood cells to ­fight any potential pathogen. The worst manifestation of a corneal in­filtrative event is a corneal ulcer," says Jeffrey Sonsino, O.D., past chair of AOA's Contact Lens and Cornea Section.

"The bacteria that creates an ulcer can eat through an intact cornea in 24 to 48 hours, so it is extremely serious."

Bacterial ulcers are usually quite obvious to the patient-causing pain, light sensitivity and decreased vision. Avoiding lens materials that could play a part in that is key.

The essence of science

Mucin balls, on the other hand, are impossible to detect by patients, and can only be viewed using high-resolution, high-magni­fication inspection of the eye with the lens on. No one paid much attention to mucin balls before this study, according to Dr. Sonsino.

"They weren't even on the radar," he says. "We noticed these things were around, but it didn't trigger a decision-making tree. After this paper, when we see them now, it will trigger a change. And that is the essence of science: 'Figure out if what you're looking at is important or unimportant.' This is an incredibly well-designed, randomized prospective multicenter clinical study and there are not as many of those as we would like to help us make clinical decisions."

"The takeaway message is, if you see mucin balls, think twice about the type of lens that patient is wearing," says Dr. Sonsino. "When I see mucin balls, I am going to switch the patient into a more flexible material and then check to see if they are a mucin ball former with that new material."

August 21, 2017

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