Impact of Ethylene Oxide Butylene Oxide Copolymers on the Composition and Friction of Silicone Hydrogel Surfaces

Abstract

The surface chemical compositions of three types of silicone hydrogel contact lenses, PureVision Ò (balafilcon A), ACUVUE Ò OASYS Ò (senofilcon A), and O 2 OPTIX Ò (lotrafilcon B), were analyzed using X-ray photoelectron spectroscopy prior to and following treatment in a test solution of diblock copolymer of poly (ethylene oxide) and poly(butylene oxide) (EO-BO). Prior to treatment, differences in surface elemental compositions of the lenses were found to reflect known bulk compositions and/or respective surface treatments. Following solution treatment, surface chemical modifications were apparent in balafilcon A and lotrafilcon B, especially in the distribution of chemical functionalities present at the surface. Only modest changes in surface composition were observed for the senofilcon A material. Atomic force microscopy (AFM) was employed to evaluate the surface topography and frictional properties of the lenses prior to and following similar solution treatments. AFM measurements in saline revealed large disparities between the coefficients of friction of the three lenses, with balafilcon A and lotrafilcon B exhibiting coefficients of friction approximately five times greater than that of senofilcon A. Lens surface treatment with the diblock copolymer test solution produced a significant reduction in the coefficients of friction of the two lenses exhibiting higher friction, yet only a small reduction in friction was observed for senofilcon A lens. Together, these results depict a strong correlation between the surface chemistry and frictional response of the lens systems as they relate to solution treatment with this specific diblock copolymer.

Oral tribology: Providing insight into oral processing of food colloids

“…Further, adsorption processes (e.g. macromolecules onto surfaces of contact lenses) (Huo, Rudy, Wang, Ketelson, & Perry, 2012), and chemical reactions (e.g. redox reactions in preparation of silver-lignin core-shell nanoparticles) (Gan, et al, 2019) can be tracked by XPS to provide insight in to the associated lubrication performance.…”

Biocompatibility in the Development of Silicone-Hydrogel Lenses

“…The modulus of the lens determines the ability of the lens to respond to the mechanical forces of the blink. Both of these factors directly affect measurable parameters of the lens surface, such as wettability [33][34][35] and coefficient of friction, [36][37][38] and contribute to the degree of biofouling and final material on eye performance. High modulus lenses are stiff and rigid under the eyelid forces and injure the adjacent tissues, cornea, and conjunctiva of the eye and eyelids, to varying degrees.…”

“…The cornea, conjunctiva, and eyelid are highly innervated with both ophthalmic and maxillary branches of the Trigeminal nerve. 38 Although the initial impetus in development of SiHy materials was to achieve extended/continuous wear for 14 to 30 days, SiHy materials have also been introduced into the Daily Disposable contact lens market. The cold neural receptors of the cornea can become sensitized with contact lens-induced dry eye and changes in the corneal nerve plexus have been noted after extended contact lens wear.…”

Sustained Release of a Polymeric Wetting Agent from a Silicone-Hydrogel Contact Lens Material

“…These include poloxamer (triblock copolymer, PEO-PPO-PEO), poloxamine (four-armed copolymer, PEO-PPO), and diblock PEO-PBO copolymer, among others. 23 , 25 Release rates of wetting agents have been correlated against their molecular weight and/or against their hydrophilic/lipophilic balance (HLB). 23 , 25 …”