LENS CARE® solution for maintenance of soft contact lences

Lens care® je is a solution used for washing, removing layers of proteins and lipids, disinfection, wetting and keeping all kinds of soft contact lenses. It is bufferand isotonic solution of Poloxamer 407, conserved with 0, 0001% of Polyhexanid.
Lens care® is the only registered solution in Serbia and surrounding. Registration was anticipated with ample clinical examinations. It’s a complex solution, belongs in the group of sterile medical devices and demands fulfilling of numerous requests for production and implementation of specific and complicated equipment.

LENS CARE® solution

Maintenance of the contact lenses

Maintenance of the contact lenses consists of three steps, and because of this those solutions are marked as three-function solutions, or three-in-one, and those functions are:

• removal of the impurities (cleaning)
• removal of lipids and proteins
• disinfection

At formulation of these preparations for contact lenses maintenance, it is necessary that the preparation protects the eye, doesn’t have negative effects on the eye, doesn’t damage the lenses and efficiently maintains the hygiene of the lenses. The main ingredient for cleaning in the contact lenses solutions is superficial active substance – copolymer of ethylene oxides and propylene oxides, Poloxamer 407 (BASF, Germany) or Lutrol F 127 (ICI Surfactant, USA). It’s a non toxic and non ion PAM, and cleans lenses of protein substances, lipids and other layers. It also conjoins the lenses surface and makes it wet and comfortable for wearing. Removal of proteins includes process of fission of molecules of proteins on shorter peptide chains which are easily removed by superficially active substance. It is necessary to wash the lenses in the solution with pH 6, 6-7, 8 and osmolarity in range of 280-320 miliosmoles/litre.

Presence of the conservancy in solution keeps them protected during the storage of lenses in the period of 30 days, if the lenses are not used. Traditional conservancies, benzalkonium chloride and thiomersal, are proved themselves as cytotoxic and lead to eye irritations.

More resent desinficint which is used in the contact lenses solutions is polyhexanide. It’s a coadunation of a large molecular mass:

• can’t penetrate in the matrix of the soft contact lenses
• it is used in smaller concentrations comparing with the traditional ones, and it’s less toxic for the eye tissue
• polyhexanide conjoins with phospholipids with negative electricity in plasma of the bacteria membranes and provokes decomposition of microorganism cells.

Maintenance of the contact lenses

Contact lenses cassettes

A cassette for contact lenses is an integral part of the disinfection system, but it is often neglected by patients. Microorganisms can form a biofilm on the cassette surface, which becomes resistant on disinfection and attracts other bacteria and polluters. Data show us that 40-55% of cassettes is bacteriological contaminated, which is the reason because it is recommended to change them at least in a three months period, and optimally monthly.

Solution LENS CARE is a water solution of thermo stabile components so it is manufactured by heating to 121°C in the minimal period of 15 minutes. Cooled solution (40°C) is filtrated through bacteriological membrane filter under pressure in the facility with the laminated currency of air of the corresponding quality, in sterilized bottles and it’s sealed with a lid with the safety ring. Predicted “best before” period for the solution LENS CARE (three years, or two months after opening of the bottle) is determined on the basis of examinations of the content of the active components and the sterility of the package after predicted period of keeping.

Contact lenses cassettes

Solutions for contact lenses

Expansion of using contact lenses, because of therapeutical or esthetic reasons, led to the appearance of large number of preparations for their keeping and maintenance of the hygiene. Some analyses show that only in the USA in the year 2005. there were 36 millions of contact lenses users.

For production of the products from this group it is necessary to pay particular attention to various things, beginning with the multifunctional demands for the solution itself, to the type and the quality of the package which a solution for the maintenance of the hygiene of contact lenses must fulfill. Since the year 1998. these solutions are no longer in the category of medicines, but in the category of medical devices (category 2 –medical devices which get in contact with eyes) according to the European directive 93/42.

With the degree of the development of the technology of materials and processes for manufacture of contact lenses, also changed and improved the quality of contact lenses. Today there are a large number of types of contact lenses which by their physical characteristics can be divided in three basic groups:

• rigid gas permeable contact lenses (RGPs) – manufactured of fluorosilicilic acrilats and flouropolimers and optimally are permeable for oxygen, and humidity of lenses and their resistance to layer are satisfying.
• soft contact lenses (SCL) consist of hydroxyethilmethacrylate (HEMA) of bar structure with the content of water in the range 3-85%. Those lenses can be ionic or non ionic, in dependence of the polarity of the lenses surface.
• silicon hydro gel contact lenses are more recent, they are present on the market since 1999. And have very large permeablity for oxygen. They are often marked as lenses that can be used also during the night.

During the usage, contact lenses can be contaminated with proteins and lipids from the film created by tears from tear glands, desqated corneal epithelium cells, pollution from surrounding (polluters-dust) or cosmetic preparations.

This provides bigger appearance of the contact lenses for microorganisms and sensibility for development of various eye infections. Among provokers’ of infections, along with pathogen and non pathogen bacteria and fungus, the most common is acanthamoeba.

Akantameba keratitis is very serious infection caused by this ameba, almost exclusively joined with wearing of contact lenses. Acanthamoeba is isolated from samples of earth, dust, community water, sea water, swimming pools, thermal baths and bottled drinking water. Cristle and Kilvington think that akantameba keratitis origins from primarily contaminated cassettes for contact lenses.

Considering all above said, a solution for maintenance of hygiene of contact lenses must be:
• compatible with the material of which the lenses consists
• non toxic for the eye surface
• manufactured according to the terms demanded by the legislation regulative GMP
• sterile, with maintenance in sterile condition for three years, or two months after opening of the package
• isotonic with tears and buffered
• destructive for all pathogen microorganisms in the eye
• efficient in removal of impurities and protein and lipid layers
• simple for use and with economical price

Solutions for contact lenses