What causes mucin balls to form under contact lenses?

Mucin balls form under contact lenses primarily due to lens dehydration. When a contact lens becomes dehydrated, the water content decreases, which can lead to changes in the lens surface. This altered surface characteristics can promote the accumulation of mucin, a component of tear film, leading to the formation of small, gel-like spheres or balls.

When the contact lens dries out too much, the interactions between the lens and the tear film change, causing the mucin to aggregate into these small balls instead of being evenly distributed. Ultimately, this formation can contribute to discomfort and even affect visual clarity for the lens wearer.

While other factors such as low Dk/t values (which represent the oxygen transmissibility of the lenses), improper lens hygiene, and lens overwear can lead to various complications with contact lens wear, they do not directly cause the specific formation of mucin balls like lens dehydration does. Thus, lens dehydration is the most relevant cause in this context.