Mary Flowers Mowrey-Mckee

COMPARATIVE CYTOTOXICITY POTENTIAL OF SOFT CONTACT LENS CARE PRODUCTS

ABSTRACT Purpose. To determine the cytotoxicity potential of soft contact lens care products and benzalkonium chloride (BAK) by two colorimetric in vitro assays on an immortalized human corneal epithelial cell line (HCE-T). Methods. Four commercial soft contact lens care solutions were tested at 1:3 dilution in growth medium. The positive controls for cytotoxicity were BAK in Dulbeccos phosphate buffered saline (DPBS) at 10, 5, 2.5, and 1.25 ppm and 1:3 dilution of DPBS as negative control. Cell viability was assayed using a novel tetrazolium compound and an electron coupling reagent (MTS/PES), and by cell membrane integrity using neutral red dye uptake and release (NRUR). Mean spectrophotometric optical density of the test samples was compared to mean optical density of the controls at 24 and 48 hours of exposure to test product. Significance was measured by ANOVA/Tukey HSD test. Results. Cell viability and cell membrane integrity tests were not significantly different between lens care solutions and the negative controls for CIBA Vision SOLOcare™ PLUS, Advanced Medical Optics COMPLETE® Comfort PLUS™, or BAK at 1.25 ppm. Exposure to Bausch and Lomb ReNu MultiPlus®, Alcon OPTI-FREE® Express® with Aldox™, BAK 10, 5, and 2.5 ppm yielded significant reduction in cell viability and membrane integrity compared to negative controls. Discussion. Assays of HCE-T cell viability by MTS/PES, and cell membrane integrity by NRUR cells yielded data that were similar to that previously reported with mouse L929 cells in tests based on the USP Elution Test. For the MTS/PES and NRUR assay methods, the solutions in order of increasing cytotoxicity potential were: SOLOCare = COMPLETE Comfort Plus < ReNu < < OPTI-FREE® Express® with Aldox.

Factors affecting staphylococcus epidermidis adhesion to contact lenses

Background. Staphylococcus epidermidis is a major causative agent of infectious keratitis associated with contact lens wear. Adhesion of this bacterium to contact lenses may contribute to the pathogenesis of infection and could be influenced by lens surface properties, packaging/storage solutions, and vary among different strains according to the level or type of adhesins expressed. Methods. Adhesion of six clinical isolates of S. epidermidis to three different contact lens materials was tested. Adhesion assays were performed on lenses immediately after removal from their packages, and also after lenses were soaked in sterile phosphate buffered saline (PBS) for 7 days to dilute the packaging solution. Results. For lenses tested immediately upon removal from their packaging, adhesion to polymacon (in PBS with 0.1% polyvinyl alcohol) was significantly greater than to etafilcon A (in borate buffered saline) and vifilcon A (in PBS). After soaking, adhesion to polymacon lenses was significantly less than to the other lens materials. This pattern was consistent for all strains, although major differences in baseline adhesion levels existed between strains, with exopolysaccharide (slime)-positive bacteria being more adherent to lenses. Conclusions. Properties of contact lens materials were not the sole determinant of viable S. epidermidis adhesion to lenses. Strain variability, including levels of exopolysaccharide expression, and the solution used for lens immersion also influenced adhesion

COMPARATIVE CYTOTOXICITY POTENTIAL OF SOFT CONTACT LENS CARE REGIMENS.: Poster #139

PURPOSE To determine the cytotoxicity potential of soft contact lens disinfection solutions. METHODS Three modifications of the United States Pharmacopeia (USP) elution test were conducted: trypan blue uptake test; regrowth of cells after exposure; and quantitation of viable cells after exposure test. Cycled lenses were also tested according to the USP direct-contact test. We compared the cytotoxicity profile of neutralized AOSept (CIBA Vision, Duluth, GA) disinfectant, SOLO-care Soft (CIBA Vision, Duluth, GA) brand multipurpose solution, OPTI-FREE Express (Alcon, Ft. Worth, TX) multipurpose disinfecting solution (with ALDOX), ReNu (Bausch & Lomb, Rochester, NY) multipurpose solution, ReNu MultiPlus (Bausch & Lomb, Rochester, NY) multipurpose solution, and COMPLETE Comfort PLUS (Allergan, Irvine, CA) multipurpose solution. Appropriate positive and negative controls were used for each test. RESULTS Neutralized AOSept, SOLO-care soft, and COMPLETE Comfort PLUS solutions were noncytotoxic by all four test methods. ReNu MPS and ReNu MultiPlus both were noncytotoxic by the USP direct contact test and the USP elution-based trypan blue uptake and cell regrowth tests, but both yielded less than 50% of viable cells. In the three USP Elution test methods, OPTI-FREE Express (with ALDOX) exhibited cytotoxicity. CONCLUSIONS These solutions have shown widely varying cytotoxicity potential. Neutralized AOSept, SOLO-Care Soft, and COMPLETE Comfort Plus were noncytotoxic by all four tests. ReNu MultiPlus and ReNu MPS inhibited the growth of cells after exposure. OPTI-FREE Express (with ALDOX) may have a higher potential for ocular irritation correlating to severe cytotoxicity in vitro.