For years, ophthalmologists believed that increased mucin ball production was either innocuous or beneficial for the cornea. One new study, however, suggests just the opposite. American researchers now say they believe mucin ball production could actually have a negative effect on contact lens wearers' overall corneal health.
Scientists at the Ohio Lions Eye Research Foundation were behind this latest study on the correlation between mucin balls and corneal health. In total, 289 people took part in this long-term study.
Researchers split this examination into two distinct phases. The first phase was during the first 30 days of the study and the second phase took place over the next 12 months.
In the first phase, researchers tested the patient's' eyes to tell which patients had higher mucin ball formation than average. Participants with eyes that produced mucin balls were referred to as "mucin ball formers," while everyone else was simply called "non-mucin ball formers."
During the second phase of the trial, researchers examined what effect mucin ball production had on the extended wear of the eyes. Interestingly, researchers discovered that people who had higher than average mucin ball production had a greater risk of a corneal infiltrative event in the second phase of the experiment.
This finding actually goes against the research team's hypothesis. Scientists involved in the study said they were expecting mucin balls to protect the cornea rather than increase the risk for infiltrative events. They based their hypothesis on a previous Longitudinal Analysis of Silicone Hydrogel (aka LASH) study that suggested mucin balls help decrease corneal issues.
For those who don't know, mucin balls are extremely small translucent spheres that appear near the cornea in most contact wearer's eyes. The vast majority of mucin balls are only around 20 to 200 micrometers in diameter and often start forming immediately after a contact wearer inserts his/her lenses. Sometimes mucin balls can simply be blinked away, but they tend to form small depressions in the cornea every time a patient removes their contacts.
The current medical consensus on mucin balls is that they pose no real threat to eye health or even contact lens comfort. Indeed, the previous LASH study suggested that mucin balls protected the eyes by forming protective microbial barriers between the contacts and the corneas. This added layer of protection was thought to give the wearer's eyes greater resilience against pathogens.
The Ohio researchers noted in their published study that although their findings were counter to their hypothesis, their results were "consistent with some other literature" on the effects of mucin balls on the cornea. When trying to make sense of this phenomenon, the study's authors wrote that the mucus layer produced by mucin balls might actually help bacterial antigens enter the cornea by breaking up important protective barriers.
This study was published in the April 2017 edition of Optometry and Vision Science under the title "Mucin Balls Influence Corneal Infiltrative Events." Johnson & Johnson Vision Care was a major financial supporter of this Ohio-based study.