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.


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).


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.

Slowing Myopia - OrthoK Case Notes

Fitting children with hard contact lenses which they will wear while sleeping at night may seem like a big undertaking, but the outcomes
continue to impress us. From the first morning these children see massive improvements in their vision - one of the most rewarding
aspects to this work.
When we met Jack* he was 6 years old, an outdoors boy who loved to read, struggling to see the whiteboard at school. Jack’s Mum is
highly short-sighted (-9.00D myopic), and his dad is moderately short-sighted (-2.50D myopic). Jack’s first prescription in December
2015 was -1.00D.
Jack also had poor visual efficiency, a risk factor for becoming more myopic. The first step was a behavioural optometry assessment
and vision therapy to improve his binocular vision. This was successful, but his distance vision remained blurred.

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At the end of 2016 Jack got his first pair of glasses. To start he only wore his glasses a couple of times a week at school. Over a 6
month period, Jack’s vision got worse, by -0.50D. If he continued at this rate, by 18 years old his prescription could track towards -
11.00D increasing the risk of serious future eye problems (retinal detachment, glaucoma and maculopathy).
This year we have fitted Jack with custom made Ortho K contact lenses to wear while sleeping. This gives him clear vision the next day
once he takes out his contacts. Importantly, wearing these contact lenses can significantly slow down his myopia progression.
When we checked Jack after his first night wearing his contacts, he commented “I can see great” and his vision was 6/6 (equivalent to
20/20). He managed to take out his lenses solo on the second morning. There are more firsts; he was able to see his parents in the
back row of assembly when he won an award at school. His family report “we are so impressed with these lenses, Jack is really excited
to be able to see clearly and positive about the process.”
Jack will have follow-up checks every 6 months to monitor his vision. So far, after 2 months of treatment his vision has not changed at
*name changed for privacy

Research into Digital Artifical Light

A new study* highlights the disruption to sleep patterns which can be caused by blue light emitted from digital devices. 

The study, at the University of Houston College of Optometry, had people wearing blue blocking filters before bed. Participants still performed their usual nightly digital routine. Results showed a 58% increase in night-time melatonin levels. Melatonin is the chemical that signals your body its time to sleep. These melatonin levels were higher than would be achieved taking over-the-counter melatonin supplements.

“The most important takeaway is that blue light at night time really does decrease sleep quality. Sleep is very important for the regeneration of many functions in our body,” said Dr. Ostrin, from University of Houston College of Optometry.

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The 22 study participants wore sleep monitors 24 hours a day. They reported sleeping better, falling asleep faster, and even increased their sleep duration by 24 minutes a night.

The largest source of blue light is sunlight, but it's also found in most LED-based devices. Blue light boosts alertness and regulates our internal body clock, or circadian rhythm, that tells our bodies when to sleep. This light activates photoreceptors, called intrinsically photosensitive retinal ganglion cells (ipRGCs), which suppresses melatonin.

Dr. Ostrin recommended limiting screen time, applying screen filters, wearing computer glasses that block blue light, or using anti-reflective lenses to offset the effects of artificial light at night time. Some devices have night mode settings that limit blue light exposure.

“By using blue filtering lenses we are decreasing input to the photoreceptors, so we can improve sleep and still continue to use our devices" she said.

Closer to home we are dispensing blue coating on lenses. This coating improves comfort looking at screens. Wearers also find the blue coat is good for driving. Blue light causes light scatter so in daylight conditions blocking this reduces glare. Please contact us if you have any questions about lens coating options.

*Study published in Ophthalmic & Physiological Optics.


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.