Don't flush your contact lenses down the sink! Contact lens plastics could be dangerous to aquatic life?

Researchers are advising us to stop flushing used contact lenses (CLs) down the sink. Instead put them out with other solid plastic rubbish.

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In the US it is estimated that around 15-20% of the 45 million American contact lens (CL) wearers flush their lenses down the sink or toilet. The result - anywhere from 6 to 10 metric tons of plastic CLs end up in wastewater treatment plants.

CLs are unlike other plastic waste (often made with a combination of polymethylmethacrylate, silicones, and fluoropolymers), so the effect of wastewater treatment on CLs was unknown. This sparked Professor Rolf Halden and colleagues from Arizona State University to find out how CLs break down and whether they pose a threat to aquatic life.

They exposed polymers found in CLs to anaerobic and aerobic micro-organisms (which would be present at wastewater treatment plants).

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They reported, “When the plastic loses its structural strength, it will break down physically, leading to smaller plastic particles which would ultimately lead to the formation of microplastics. Aquatic organisms can mistake microplastics for food and since plastics are indigestible, this dramatically affects the marine animals’ digestive system. These animals are part of a long food chain. Some eventually find their way to the human food supply, which could lead to unwanted human exposure to plastic contaminants and pollutants that stick to the surfaces of the plastics.”

The researchers have also called on CL companies to address the way their products are ultimately disposed.

Macular Degeneration Trigger Enzyme Discovered

The discovery of a crucial trigger for dry macular degeneration (AMD) – an enzyme called cGAS – could lead to the development of a drug to prevent disease progression. 

This discovery, at the University of Virginia School of Medicine, was a surprise. Drs. Jayakrishna Ambati and Nagaraj Kerur had determined that cGAS plays an important role in the body's immune response to infections detecting foreign DNA, but its role in dry AMD was unexpected. 

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Myopia Management - Resources

Short-sightedness is a global public health problem. Most people think of myopia (the medical term for short-sightedness) as an inconvenience because the blurred vision it causes is easily corrected with glasses or contact lenses. The problem is that a myopic eye is a longer eye and so the light sensitive part at the back of the eye is stretched. This can lead to a number of eye diseases in later life, such as glaucoma, maculopathy and retinal detachment. Higher levels of myopia (stronger glasses) correlates to greater problems.

Experts are also concerned because the number of people with myopia is increasing. Research suggests that by 2050 it will affect half the world’s population. Myopia normally develops in children and increases in prevalence and amount during the teenage years. We know that about 30% of teenagers in the UK have myopia, and in some East Asian countries around 80% of teenagers have myopia.

Here are the predictions: 

  • 5 billion myopes by the year 2050; up from 1.4 billion in 2000
  • 1 billion high myopes by 2050; a five-fold increase from 2000
  • Number with vision loss from high myopia to increase seven-fold from 2000 to 2050; myopia to become a leading cause of permanent blindness worldwide.

The impact of these levels of myopia on all areas of society is enormous due to the cost of eye examinations, glasses and treatment of eye disease. The reasons why myopia develops are not fully understood; the prevalence has increased too quickly to be explained solely by genetics.

We know that our visual environment also has a role in myopia development. Our lifestyle has changed significantly over the last 50 years, with greater time being spent indoors on computers, tablets and smartphones. It is the lack of time that children spend outdoors that seems to trigger myopia development.

Globally there are many people actively looking for ways to prevent myopia, or, if it has started, at ways to slow its progression. It has challenged our traditional approach to myopia, test vision and make up stronger glasses as needed. Now we are actively helping people consider alternatives which may help reduce progression, and increasing understanding of this phenomenom.

Here are some resources:

Australian Optometrist Dr Kate Gifford has developed an online tool for families to work out the risk of children becoming myopic - My Kid's Vision

Myopia Prevention is a good overview.

Nature published this great article about the Myopia Boom.

Please contact us if you would like to discuss myopia.