Not a dry eye in the house

A researcher’s own contact lens discomfort drove him to create a new machine to help manufacturers create more comfortable contact lenses in the future.

Stanford University PhD student, Saad Bhamla, told OT that his research aimed to tackle the discomfort caused by the break-up of the tear film by contact lenses.

Mr Bhamla and his university supervisor, Professor Gerald Fuller, have closely studied the tear film and, specifically, the lipid layer that sits atop the watery layer, to better understand it.

The lipids in this upper layer have ‘viscoelastic’ properties that allow them to stretch and support the liquid layer. Mr Bhamla said thinking of this lipid layer as a swimming pool cover is a good analogy.

He added: “You will sometimes see the guards at the Stanford Avery pool run over the surface of the covered pool. The mechanical structure is very thin, but it protects the whole bulk of the liquid.”

The lipid layer also reduces the evaporation of the tear film into the surrounding air, Mr Bhamla explained.

Studies have shown both the lipid and watery layer of the tear film are affected by contact lens wear, he noted.

With these insights, the pair built a machine that can reproduce a lifelike tear film on the surface of a contact lens. With it, designers and manufacturers will better understand how current and novel materials and solutions affect a tear film, and therefore, the comfort of the eventual wearers.

The machine has been aptly named the Interfacial Dewetting and Drainage Optical Platform, or i-DDrOP for short.

“Until we developed the i-DDrOP, there was no instrument to realistically make these studies in-vitro. 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. We felt we could definitely do better than that,” said Mr Bhamla.

Mr Bhamla had to stop wearing contact lenses as a student, finding them increasingly uncomfortable. “Focusing my PhD thesis to understand this problem was both a personal and professional goal,” he explained.

Image credit: Niek Beck/Creative Commons