Contact Lens Care & Compliance
A New Multipurpose Solution Enters the Market
BY MICHAEL A. WARD, MMSC, FAAO
Bausch + Lomb introduced its new soft lens multipurpose solution called Biotrue last month at the American Optometric Association’s annual meeting in Orlando. B+L describes it as a bioinspired product (see the Contact Lens Spectrum Special Edition 2010) that will meet the demands for modern soft lens care, disinfection, and comfort.
Disinfectants Biotrue’s formula employs a powerful dual disinfection system of polyhexamethylene biguanide (PHMB) plus polyquaternium-1 (PQ-1). PHMB is the classic preservative/anti-microbial used in Renu Fresh (previously ReNu MultiPlus) (B+L), Complete MPS (AMO), and Aquify MPS (Ciba Vision). Polyquaternium-1, also found under the Polyquad trade name, is the primary antimicrobial in Alcon’s Opti-Free Express and Opti-Free Replenish. PHMB and PQ-1 have different modes of action, which act synergistically when combined to yield an enhanced antimicrobial efficacy against bacteria, fungi, and protozoa. B+L claims significant antimicrobial activity against Acanthamoeba polyphaga trophozoites and cysts as well as against all challenge bacteria and fungi.
Although Biotrue meets the criteria for a stand-alone contact lens disinfection product, B+L has chosen to launch this new MPS with a rub-and-rinse regimen and soak time of four hours.
Buffer Biotrue is borate buffered, which matches the pH of healthy human tears at 7.5. Borates can go beyond buffering capabilities and may also exhibit microbiostatic and even microbicidal effects, therefore contributing to a product’s antimicrobial effectiveness.
Lubricant Hyaluronan (a.k.a. hyaluronic acid, sodium hyaluronate) is Biotrue’s primary lubricant. Sodium hyaluronate is the sodium salt of hyaluronic acid (HA), which is a naturally occurring disaccharide biopolymer. HA is a structural polysaccharide composed of repeating units of N-acetylglucosamine and glucuronic acid. It is available in a wide range of molecular sizes and weights, and it has considerable viscoelastic properties and a high capacity to imbibe water (HA can bind up to 1,000 times its weight in water). Sodium hyaluronate solutions strongly adhere to the mucin layer of the tear film, creating a persistent water-retaining layer that resists evaporation. For this reason HA has been successfully used in the rewetting drops Blink Contacts (AMO) and Aquify Long-Lasting Comfort Drops (Ciba). Sodium hyaluronate is also found in human synovial fluid of knee joints, the vitreous humor of the eye, cartilage, blood vessels, extracellular matrix and skin. HA naturally binds to receptors in the corneal endothelium, which makes it useful as a viscoelastic (e.g. Healon, AMO) to protect the corneal endothelium during intraocular surgery (see the Contact Lens Care column titled “New Rewetting Drops Improve Patient Comfort,” from the November 2004 issue.)
A New Beginning
B+L also claims that its new solution will protect necessary tear proteins lactoferrin and lysozyme from denaturing. These proteins in their denatured states are in part responsible for some ocular inflammations such as giant papillary conjunctivitis.
From 2004 to 2006 we witnessed the last significant introduction of new soft contact lens care products from the major manufacturers. The industry has learned a great deal since then. B+L’s new Biotrue is likely the beginning of the next wave of improved lens care products formulated based on the lessons learned from the past. CLS
Mr. Ward is an instructor in ophthalmology at Emory University School of Medicine and Director, Emory Contact Lens Service. You can reach him at email@example.com.