Alisa Sivak, MA, DipEd

Alisa assists the Centre for Contact Lens Research by writing and editing publications, reports, grant applications, and educational communications.

The following is part one of a synopsis of the 2008 meeting of the BCLA:
Nancy Keir and colleagues (Centre for Contact Lens Research, University of Waterloo, Canada) reported that they found no association between in vivo wettability, ex vivo wettability, and comfort when they examined lotrafilcon B and senofilcon A lenses.

A recent study conducted by the Institute for Eye Research (IER, Australia) revealed unique ocular staining with different solution-lens combinations: hydrogen peroxide causes almost no staining.  This group has developed a “matrix” in the hopes of minimizing SICS by helping practitioners choose the best combination of lens and solution for each patient. Mohinder Merchea and colleagues (Bausch & Lomb) conducted a study evaluating the relationship between lens-solution induced staining and inflammatory markers in tears.  Results indicated no association between acute inflammatory response and extent of solution associated staining.

According to Philip Morgan and colleagues (Eurolens Research, UK), silicone hydrogel lenses offer sufficient Dk/t to avoid both peripheral and central corneal swelling, compared to hydrogel materials which induce swelling either peripherally or both centrally and peripherally.

Stephanie Crass and colleagues (Anglia Ruskin University) confirmed that infrared spectroscopy can be used to examine surface dehydration of silicone hydrogel lens materials.  Results indicated that as materials dehydrate their surfaces are less effective at attracting water.

Soft contact lenses produce higher order aberrations, which can affect a person’s vision.  Jennifer Zuba and Paul Jeatran (Bausch & Lomb) reported that aspheric lens surfaces can offset positive spherical aberration by providing negative spherical aberration similar to that found in the uncorrected eye.  All other lenses investigated (lotrafilcon A and B, galyfilcon A and comfilcon A) exhibited a linearly increasing trend that under-corrected for average spherical aberration at low minus powers and did not consistently reduce positive spherical aberration.  Comparing balafilcon A (front surface aspheric and back surface bi-curve) and senofilcon A (front surface tri-curve and back surface monocurve) lenses, Shehzad Naroo and colleagues (Aston University) only found a statistical difference with respect to the coma high order aberration.

Lyndon Jones and colleagues (Centre for Contact Lens Research, University of Waterloo, Canada) reported that both surface-modified and non-surface-modified silicone hydrogel materials attract relatively low levels of protein from the tear film; in fact, all silicone hydrogel materials collect low levels of protein (with balafilcon A lenses collecting significantly more total protein and total lysozyme than comfilcon A lenses).  The amount and percentage of denatured lysozyme varies depending on the absence or type of surface treatment methodology. This group also reported that even after three months of wear, a novel lathe-cut silicone hydrogel lens material collects the same quantity and type of protein as other similar surface-coated silicone hydrogel lenses after one month of wear. (125 – 126 – 4 abstracts)

Mary Mowrey-McKee and colleagues (CIBA Vision) evaluated mammalian cell viability with silicone hydrogel contact lenses cycled in soft contact lens care products using an in vitro cell culture model.  They reported that lenses cycled with peroxide and PHMB-based solutions were non-cytotoxic while those cycled in a polyquad-based product were found to be cytotoxic. (129)