If there is one major advancement in the world of contact lenses in recent years that has made the biggest impact on the industry, then it would have to be silicone hydrogel. The key date in this development is 1999, when Ciba Vision became the first company to introduce silicone hydrogel contact lenses under its Night and Day brand, and this was quickly followed by PureVision contact lenses from Bausch and Lomb.
Eyes need oxygen
The importance of this development is all about the ability to transmit oxygen to the eye, which is a vital requirement for eye health. The cornea needs to get oxygen directly from air and a lack of oxygen will result in corneal damage as well as other eye problems.
That is the reason behind the importance of silicone hydrogel since it has a much higher oxygen permeability than other hydrogels and allows as much as eight times more oxygen to reach the eye than other hydrogels1. The man credited with developing silicone hydrogel is Kyoichi Tanaka, who patented the technology in 19792. It is specifically the oxygen permeability of silicone that made the breakthrough in this advancement possible.
Silicone hydrogel was originally developed for lenses intended to be worn on a continuous basis and overnight for periods of up to thirty days. However, since its introduction silicone hydrogel has been used in all types of lenses including monthly disposable lenses and daily disposable lenses, which have become hugely popular due to the comfort and flexibility they provide as lens wearers do not need to clean or disinfect them.
Research and development
Research and development has continued into silicone hydrogel and some well-known brands of fortnightly and monthly disposable contact lenses, such as Acuvue Advance and Acuvue Oasys, are made from so-called ‘second generation’ silicone hydrogels, and for example come with UV protection and are softer and have greater wettability.
Acuvue also has a brand of daily disposable contact lenses that are made from silicone hydrogel: 1-Day Acuvue TruEye. But the industry has not stopped there and now there are even third generation silicone hydrogels, such as CooperVision’s Biofinity brand of lenses, which also has very high oxygen permeability and does not need a wetting agent.
New era dawning
All contact lens manufacturers are striving towards three common goals: to produce contact lenses that are extremely comfortable and which promote eye health and provide excellent vision. The launch of Ciba Vision’s Dailies Total 1 daily disposable contact lenses marks a new chapter in the story of silicone hydrogel. They are the first water gradient silicone hydrogel contact lenses on the market. This means that the water content increases from its core to the outer layer and according to Ciba Vision these lenses have the highest oxygen transmissibility of any daily disposable contact lens3.
Talk to your optometrist
Silicone hydrogel lenses can correct all types of eye conditions from astigmatism to presbyopia. With all the available choice, from continuous wear contact lenses to daily disposable ones, it is worth consulting your optometrist if you are unsure about which lens may be best for you. But one thing is certain: you won’t be lacking in different options.
1 Silicone Hydrogels: The Evolution of a Revolution. By Deborah Sweeney, BOptom, PhD, FAAO, Desmond Fonn, DipOptom, MOptom, and Kylie Evans, BA. Contact Lens Spectrum
3 Background information provided by Ciba Vision