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Have you ever thought about what happens to your contact lenses when you throw them away?

There is a significant environmental impact when you throw away your contact lenses. The plastic matter from disposable contact lenses when discarded can contaminate water supplies.
Many people have used disposable contact lenses, often daily wear contact lenses, all their adult lives, and we are only now beginning to ask if anybody has investigated what happens to these plastic lenses when people discard them.
Researchers at Arizona State University in the USA have just presented a research paper at the American Chemical Society in Boston about the impact of disposing of plastic contact lenses into the water system.
They discovered that 15 to 20 per cent of contact lens wearers throw their used lenses either into the toilet or down the sink. The lenses absorb water and flow into the water treatment plants. The research team estimate that in just one year between 6 and 10 tonnes of plastic lenses end up in treated water, which then goes into rivers and lakes in the USA. Because these plastic contact lenses are heavier than water they sink to the bottom of the rivers and lakes and this presents a threat to aquatic life. In particular, aquatic species that live at the bottom of the sea, lake or river bed can ingest the contact lenses.
It is difficult to see contact lenses when they are in the water treatment plants because they are transparent. Much of the material used in plastic bags and other forms of discarded plastic is polypropylene. Polypropylene is present in car batteries and textiles; however, contact lenses comprise a combination of polymethyl methacrylate, silicones and fluoropolymers that create a soft material which allows the oxygen to pass through the contact lens to reach the eye.
The trouble is that when these contact lenses go into the water treatment plants, they absorb the bacteria and micro-organisms present. This absorption process causes the lenses to break up and decompose into much smaller particles of plastic, and therefore they become micro-plastics. The principal problem is that aquatic life will eat these micro-plastics and they enter the food chain which forms part of our diet. So ultimately we are probably eating our own contact lenses, albeit as microplastics.
If you are having trouble with your contact lenses, have dry eyes or keratoconus, or if you don’t see clearly with lenses, it is time to talk to our consultant corneal and ocular surface specialist, Mr Sajjad Ahmad.


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