CE Marking

THE FOLLOWING INFORMATION IS PROTECTED BY COPYRIGHT AND IS NOT TO BE COPIED OR SUPPLIED TO ANY OTHER  PARTY WITHOUT THE WRITTEN PERMISSION OF POLYMERIC SCIENCES

HISTORY OF BIOGEL^® MATERIALS

The Biogel materials are copolymers of methyl methacrylate and N vinyl pyrollidone. They have been manufactured since 1974 and their stability and clinical safety are well documented in the contact lens literature. Accordingly we would advise that for CE marking both the biological compatibility, clinical safety and stability of the material can be accepted as being completely satisfactory. A shelf-life of at least five years can be claimed, subject to the packaging of the lens maintaining the sterility, and limiting any moisture loss. However even if the lens were to completely dry out, upon re-hydration the original parameters would be completely restored.

Like all current soft lens materials, lenses made from Biogel materials will become deposited with lipids and to a smaller degree proteins, and may become contaminated with micro-organisms during usage. Therefore it is important that the lenses are fitted by a qualified contact lens practitioner who fully informs the patient about lens care and maintenance, and the normal hazards of contact lens wear. The Biogel materials have been found to be compatible with all the usual hydrophilic contact lens care products, and may be disinfected by heat as well as chemical means. Depending upon the water content, the Biogel materials have been used in all modes of wear, including extended wear.

The ingredients and manufacturing methods used by Polymeric Sciences are the same as in 1974. Process improvements have not altered the basic formula or method of production.

Manufacturing and material reproducibility

As an indication of the reproducibility of typical hydrophilic materials during actual production, the data below was abstracted from the records of  Polymeric Sciences. The data was selected randomly from the results of batches made for contact lens applications and two aspects of the results should be noted;

(a) the materials are high water uptake systems of 60% and 75% which are significantly more liable to variations of linear expansion ratio and refractive index than lower water content materials,

(b) the linear expansion ratio is an exceptionally subtle and sensitive indicator of the overall efficiency and reproducibility of the polymer manufacturing process. Variations of linear expansion have been found to be closely correlated to:

- refractive index variations,

- incomplete polymerisation resulting in excessive residuals for wash-out on hydration,

- and residual stressing resulting from inadequate post cure treatment.

Reproducibility

Data for four random samples of material released for sale and distribution. The linear expansion is measured by a travelling microscope with the sample totally immersed in normal saline and maintained at 25° C. Samples are cut from the top and bottom of two rods taken randomly from the production batch:

Biogel 75G - 74% Water content

Mean of 20 batches:   1.623      SD:   0.0088

Biogel 60 - 61% Water content

Mean of 11 batches:   1.3948     SD:   0.0096

MATERIAL BLANK DIMENSIONS

Biogel materials are normally supplied fully trimmed to the following specification:

Diameter:   12.70  ± 0.02 mm

Thickness:  5.00  ± 0.10 mm

MATERIAL ACCEPTANCE

It shall be a condition of supply of material to any customer that the purchaser shall carry out an acceptance test upon each Lot of Biogel material delivered to ensure that the material is suitable for use by the customer. The form of acceptance test is at the purchasers discretion, but shall at least confirm the expansion of the material upon hydration.

Any warranty will not exceed replacement of material or refund of monies paid for same.

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