TKL is technical director and member of the board at Chempilots a/s (Denmark) with projects and general management responsibilities. TKL has managed several major customer projects over the years, including development of new chemistry and processing technology for soft contact lenses. His areas of interests include organic and polymer chemistry, product engineering, and management.

The ideal soft contact lens (CL) would be a lens that you would wear for years without removal. The lens should be comfortable and provide full correction and superb visual acuity.

Current soft contact lens hydrogel materials have their limitations in wear time mainly due to too low oxygen permeability and lens contamination by proteins and/or lipids. This is why many wear schedules prescribe that lenses are taken out at night, are cleaned and disinfected and replaced on a 1, 7 or 14 day basis.

The contact lens industry has for many years tried to develop truly extended wear materials so far with limited success. The main problem is that high oxygen permeability needs to be achieved by incorporation of either silicone or fluorine groups, that all are highly hydrophobic and cause problems with wetting of the lens. Two major approaches have been used to address this problem:

• Synthesis of hydrogels incorporating high amounts of either silicone or fluorine
• Surface modifications of the resulting highly oxygen permeable lenses making them more hydrophilic in the surface which improves wetting.

The position of a contact lens on the eye is locked which means that the design solution used for bifocal or multifocal glasses cannot be used with CLs. The design of a well functioning bifocal CL is a big challenge demanding extremes in micro machining capability and accuracy.

The talk will in more detail outline the requirements for suitable contact lens materials as well as discuss the latest advances with regard to design and optics of the lenses