A disadvantage of contact lenses is that they often get very dirty. A PhD student at the University of Twente has found a material that makes it take longer for the lens to get dirty. It involves the polymer Poly (Ethylene Glycol) Poly (Urethane Isocyanurate), or PEG PUI. He obtained his PhD on the subject last Friday.
Contact lenses are worn more often and for longer periods of time, with the result that the lenses become increasingly dirty. Over time, proteins and bacteria attach themselves to the surface. This is not only annoying for vision - as the lens becomes increasingly cloudy - but also dangerous as it increases the risk of infections of the eye.
PEG PUI
The material studied by researcher Piet Driest, Poly(Ethylene Glycol) Poly(Urethane Isocyanurate), or PEG PUI for short, does not get dirty as quickly as current materials. "The material is quite inert. This makes it difficult for bacteria and egg proteins to adhere," Driest says in a press release. In his research, he compared the material to commercial contact lenses. After 24 hours in a solution of proteins, on average twice as few proteins adhered to PEG PUI than to the commercial lenses.
An additional advantage is that the new material has a higher refractive index than most contact lens materials. "This means you can make thinner contact lenses from it, which increases wearing comfort," Driest said. The study found that the degree of flexibility, strength and transparency is comparable to that of current materials.
Burns and aircraft paint
To make PEG PUI, Driest combined materials for aircraft paint and hydrogels for burns. Driest says: "The hydrogels for burns already had potential for contact lenses, but were not yet robust enough. By combining it with ingredients for aircraft lacquer, we did manage to make these hydrogels sturdy enough for application as contact lenses." In addition, the aircraft lacquer also contributed to the inert properties that now keep the lenses so clean.
It may be some time before contact lenses made from PEGI PUI are available. "At the moment, the material does not yet allow enough oxygen for the eye to pass through," he says. That problem could possibly be solved, according to Driest, by combining the material with silicone, which is currently widely used in contact lenses and allows much more oxygen to pass through.
Piet Driest conducted his research in collaboration with Covestro, a German company that produces, among other things, polymers for the paint industry.
Source: University of Twente/De Ingenieur.
