Silicone Hydrogel Contact Lenses
Roughly 125 million people around the world wear contact lenses and almost all of them have experienced the problems of hypoxia – a condition that arises when the cornea doesn’t receive enough oxygen.
Contact lenses create a physical barrier to the surface of the cornea. Hypoxia associated with long-term lens wear can lead to conditions such as corneal swelling, redness, blood vessel growth, thinning of the cornea, vision loss, predisposition to inflammation and infection, and reduced wearing time.
In the 1980s, UNSW scientists including Brien Holden and George Mertz, wrote the recipe for hypoxia-free contact lenses. They did this by running trials with subjects sleeping in lenses to determine the optimal oxygen transmissibility.
In the early 1990s, Australian and global collaborators were brought together in the Cooperative Research Centre for Eye Research and Technology with industry partners to implement ‘the recipe’ and engineer the lenses. The permeability threshold they needed to achieve was known as the Holden–Mertz Criterion.
Holden and UNSW Professor Athur Ho led the global project. It included UNSW's Professors Debbie Sweeney, Klaus Schindhelm and Eric Papas, and up to 90 other researchers working across eight locations around the world.
The result were revolutionary contact lenses containing both silicone and hydrogel polymers in a structure that allowed the transmission of oxygen as well as fluid through the lens to the surface of the eye. The transmission of oxygen and fluid are both essential for eye health.
Industry partner CIBA (now Alcon) Vision Care called the silicone hydrogel contact lenses Focus Night and Day. The lenses virtually eliminated the problem of hypoxia and provided a platform for the delivery of many important therapies such as the slowing of myopia in children.
The lenses were sold for the first time in 1999 and subsequently licensed through a partnership to all the major contact lens companies. Sales over the last 14 years have exceeded US$20 billion and the collaboration has generated over US$1 billion in research funds and over US$200 million in royalties for the CRC collaborating partners.
“This technology completely changed the paradigm for contact lens technology and is now the standard material for the industry, all from an innovative group of scientists, engineers and clinicians,” says Tim Grant, Head of Professional Marketing for Asia Pacific, Alcon.
Today, around half of all contact lenses fitted globally are manufactured from these silicone hydrogel materials.
“Australia has developed a reputation for producing the most innovative science in the eye-care field,” says Holden. “Many of the royalties from the sale of our products have been reinvested in further research, postgraduate education and humanitarian programs to build sustainable eye-care systems in developing communities.”