A clear perspective with contact lenses
New revision of DIN EN ISO 11986 Ophthalmic optics - Contact lenses and contact lens care products - Determination of preservative uptake and release
Contact lense care products play a key role in ensuring re-usable contact lenses are hygienic and do not harm the eyes. The proper preservation of contact lens care products supplied in multi-use containers is absolutely necessary if these are to retain their effectiveness and maintain their performance from the first time the container is opened until the time it reaches its discard date.
Contact lens are often made of materials that tend to absorb (and re-release) aqueous solutions. This is a side-effect of material optimization with a view to making the contact lenses more comfortable to wear. It has to be taken into consideration when specifying formulas for care products intended to be used with certain contact lens materials. Special attention needs to be paid to the uptake (and release) of preservatives. Contact lens care products and systems need to be designed to prevent the substances they contain becoming concentrated in the matrix or being released at a later date while the contact lenses are being worn.
DIN EN ISO 11986 provides general specifications for the selection of test methods, preparation of samples and test procedures relating to the uptake and relase of preservatives from contact lenses. It is primarily aimed at manufacturers of contact lenses and contact lens care products, as well as establishments that carry out such tests on behalf of manufacturers.