Stanford researchers have tried to alleviate the inconvenience of the contact lenses by advancing the understanding of how natural tears keep our eyes comfortable and developing a machine for designing better contact lenses.
The work was inspired by a graduate student's dry eyes.
Saad Bhamla, a Stanford postdoctoral scholar in bioengineering who conducted the work as a graduate student in Gerald Fuller's chemical engineering laboratory at Stanford said as a student he had to stop wearing lenses due to the increased discomfort, adding focusing his PhD thesis to understand this problem was both a personal and professional goal."
Bhamla was alone as more than 30 million Americans currently wear contacts, but roughly half of them switch back to glasses because of contact lens-induced symptoms such as dry eye. Bhamla and Fuller suspected that most of the discomfort arises from the break up of the tear film, a wet coating on the surface of the eye, during a process called dewetting.
They found that the lipid layer, an oily coating on the surface of the tear film, protects the eye's surface in two important ways through strength and liquid retention. By mimicking the lipid layer in contact construction, millions of people could avoid ocular discomfort.
In their most recent study, Bhamla and his co-authors outline two functions of the lipid layer. One is to provide mechanical strength to the tear film. Lipids in this layer have viscoelastic properties that allow them to stretch and support the watery layer beneath them.
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The key to producing comfortable contact lenses, then, involves designing lenses that don't destabilize the tear film. Manufacturers recognize the importance of protecting the eye's natural tear film on a contact lens surface to minimize painful symptoms such as dry eye, but it is not an easy thing to measure.
With the ability to accurately recreate a tear film on the contact lens surface and test how quickly it breaks up, manufacturers are now armed with the tools to make a more comfortable lens that protects users from the painful side effects of wearing contacts.
The study is published in the journal of Investigative Ophthalmology & Visual Science.