Do your eyes dry out when you wear contact lenses? That's because your "tear film," a kind of protective cover over the layer of moisture on your eyeball, is disrupted by the lens siting on top of it. And a new kind of contact lens, which leaves this film intact, may now be possible thanks to new research from Stanford University.
Stanford postdoctoral fellow Saad Bhamla, one of the project's researchers, compares the tear film to the cover of a swimming pool. It's a lot thinner than the liquid it covers, but it prevents evaporation and also offers protection.
Bhamla and his colleague Gerald Fuller tested their theory that dry eyes are a result of contact lenses breaking up this tear layer. Bhamla wears contacts himself, so he had some skin in the game, as it were.
Their latest study details the role of meibum, and oily lipid layer secreted by glands on the upper and lower eyelids. Previously, meibum was thought to be there mainly to help prevent evaporation, but Bhamla and Fuller found that it may also be there to help stabilize the eye's "swimming pool cover," thanks to its "remarkable viscoelastic properties." The role of meibum wasn't properly understood before because experiments away from the actual eye were conducted at room temperature, whereas meibum melts at the higher temperatures in our bodies—kind of like how chocolate melts in your mouth, but not on the countertop.
"Some people are studying contact lenses by holding them up to a light, dipping them in water, and looking at them to see if the tear film breaks up," Bhamla told Stanford News. "We felt we could definitely do better than that."
The discovery of meibum's importance in tear retention means that contact lens manufacturers can now design lenses or products which preserve it, meaning that your eyes won't dry out when you wear them, and that they'll be a lot more comfortable in general.