Letter: Plastic - friend or foe?

The timely article ‘View from the British Contact Lens Manufacturing Association (BCLA)’ in Optician, 7.9.18, stresses the need for manufacturers to encourage the recycling of plastic used in contact lens manufacture. The article claims: ‘Plastic is the scourge of the planet right now, polluting our oceans and having a hugely detrimental impact on the environment.’ While there is obvious merit in the encouragement to recycle plastic, which the article does, there is a much more fundamental approach needed, that is, to reduce its use.

A review of the various contact lens manufacturing technologies shows the almost universal reliance on cast moulding technology. This involves the manufacture of three separate carefully engineered plastic components (excluding the lens itself, which requires a miniscule amount of biocompatible polymer). One concave optical-moulding is required to form the front surfaces of the lens while another convex optical-moulding is required to form the back surfaces of the lens. After lens formation, the lens then has to be transferred to the third, and largest, moulding which is used to contain the lens and packing liquid ready for foil-lidding and sterilising before storage and shipping to the wearer. Hundreds of millions of contact lenses are made each year using cast moulding with little more than superficial design variation between manufacturers (the relevant patents having long-since expired) with scant regard being given to minimising the weight of plastic used – until now.