The President and CEO of Polymer Technology Group, Robert S. Ward, along with Jean Jacob, Ph.D., professor of ophthalmology at Louisiana State University Health Science Center (LSUHSC), presented a report during the 234th National Meeting & Exposition of the American Chemical Society (ACS) at the Boston Convention & Exhibition Center. Their report (The Polymer Chemistry of Contact Lenses: Improving Comfort with Bulk and Surface Modification) focused on the bulk and surface properties required in silicone hydrogels and innovative PTG processing that allows scale-up from small R&D formulation to automated manufacturing for producing silicone-hydrogel polymers in bulk quantities.
“Silicone-hydrogels make possible a new generation of ‘super-permeable’ contact lenses that can transmit unprecedented amounts of oxygen to the cornea and, in some cases, enable 30 consecutive days of ‘extended wear’ without removal,” said Bob Ward. “Silicone-hydrogel contact lenses represent a breakthrough over traditional hydrogel soft contact lenses because silicone permits so much more oxygen to pass through the lens, which is essential for a healthy cornea,” added Ward. “In fact, these next-generation lenses allow as much as seven times more oxygen to permeate than previous contact lenses, which is why they are becoming very popular with both wearers and eye care professionals. Most users find silicone-hydrogel lenses much more comfortable to wear than traditional hydrogel lenses, and this is dramatically growing the market for silicone-hydrogels.”
In addition to increased oxygen permeability, comfort is improved through control of surface chemistry, without which high-silicone lenses might actually adhere to the eye. Thus, the success of silicone-hydrogel lenses comes from well-known bulk modifications of the lens material (the inclusion of silicone), combined with sophisticated surface modifications that convert the normally hydrophobic surface of silicone to a very wettable, hydrophilic surface that discourages protein accumulations and supports a normal ‘tear film’ on the outer surface of the lens.