Is Short-Sightedness (Myopia) Causing My Eye Floaters?

For us to be able to see, light must enter our eyes and be focussed on to the retina, the light-sensitive layer at the back of the eye. 

The eye contains two parts for focussing light: the lens and the cornea. Light will first pass through the cornea (the clear outer layer at the front of the eye), and then the lens (a clear middle part of the eye). This causes the light to refract, or bend, so it is focussed directly on to the retina .

Short-sightedness is part of a group of several visual defects, including long-sightedness (hyperopia) and astigmatism, which are classed as refractive errors. These defects cause blurred vision due to light not focussing correctly on to the retina. Refractive errors reflect a mismatch between the length of the eye and its optical power , which can occur for a number of reasons:

• Eyeball length – the distance between the front and back of the eye is too long or too short, meaning light entering the eye does not focus on the retina correctly.

• Lens aging – the lens can stiffen as we age and cause the eye to struggle to focus correctly.

• Cornea shape – If the cornea is too shallow or steep, or not evenly curved in all directions, then it will not focus light onto the retina correctly.

Short-sightedness most commonly develops in young children, while the eye is still growing, with onset usually occurring between the ages of 6 to 13. 

Progression continues through the teenage years as the length of the eye changes and tends to stabilise by the age of 18 , with eye growth stopping at around 20 years old. More recent research has shown that short-sightedness can start at or progress into adulthood, after eye growth has stopped. 

The visual system has an active process to maintain the optimum light focussing distance in the eye and keep the eye focussed when looking into the distance (emmetropia). As the eye grows, the lens can stretch so that it flattens and thins to reduce its focussing power to compensate for the increases in eye length. When this process fails to occur adequately the eye becomes short-sighted.

While eye experts are unsure of the exact causes, it is commonly believed that both genetic and environmental risk factors play a role in the start and progression of short-sightedness, such as:

• Ethnicity – certain groups of people have higher incidence of short-sightedness than others.

• Family history – Short-sightedness tends to run in families, with short-sighted parents increasing the likelihood of having short-sighted children.

• Time outdoors – Studies have shown not spending enough time outdoors is linked to short-sightedness incidence.

• Near vision activity – Spending more time doing work at short distances (known as “near work”) such as reading or using screens like smartphones or computers, has been shown to increase the odds of being short-sighted in children and adults . 

Now that we understand what short-sightedness is and what some of the potential risk factors are, let’s take a closer look at how the condition can be linked to the formation of eye floaters.

“Eye floaters are black or grey shadows and dark spots which can drift in your field of view and move with eye and head movements. Floaters are more obvious against bright backgrounds and are heavily associated with aging as structural and molecular changes to the vitreous humour, a clear gel-like fluid that fills the eye, cause it to liquefy and contract” - Milston et al 2016.

Collagen, hyaluronic acid, and water are the major structural molecules of the vitreous, which also contains different antioxidant molecules and enzymes.

Events such as the dissociation of hyaluronic acid and collagen can cause the vitreous gel to liquefy and collagen aggregates to form. From this, further disruption of the vitreous can occur from the formation of pockets of liquid (called ‘lacunae’). 

These opacities can cause shadows to be cast onto the retina at the back of the eye, which appear as floaters in our vision.

The degradation in vision as a result of floaters is medically referred to as vision degrading myodesopsia (VDM). The disruption to our vision by VDM has been shown quantitatively using ultrasound scans. Contrast sensitivity function (CSF) is a quantitative measure of our ability to perceive sharp images and clear outlines of small objects that has been shown to diminish in patients with floaters, which can significantly impact psychological well-being and quality of life. 

Floaters have anecdotally been reported to be common in short-sighted people, and surveys have shown short-sighted people to be more likely than those with normal vision to report having moderate or severe floaters.

As it turns out, myopic vitreopathy is in fact the leading cause of vitreous floaters and VDM in young people. As people become more short-sighted, the length of the eyeball between the cornea and retina increases. This stretching of the eyeball disrupts the vitreous structure and we see in short-sighted eyes that the vitreous is particularly liquified , meaning floaters can likely form.

As the proteins and fibres of the vitreous clump and the gel degenerates, the gel may contract and separate from the retina. This is called posterior vitreous detachment (PVD), and comparative studies have shown that PVD develops at a significantly younger age in highly short-sighted eyes . This, along with retinal detachment and retinal tears, can cause the sudden onset of significant floaters, as well as flashes of light in your sight and blurred vision.

There has been research to support the notion that there is a causal relationship between short-sightedness and eye floaters which corresponds to a deterioration in visual function. 

A study by Nguyen et al assessed 79 participants who were either myopic or non-myopic, and either had PVD or not. They found that there were significant correlations between increased eye axial length with both increased vitreous fibrous liquefaction and a decrease in visual CSF. 

The deterioration of vitreous structure and contrast sensitivity were worsened by the presence of PVD. These results suggest that as short-sightedness progresses, the deterioration of the vitreous structure too progresses, causing more significant floaters.

While we have established that the structural changes caused to the vitreous as a result of the progression of short-sightedness can result in floater formation, studies have highlighted oxidative stress as a common process which can play a role in the development and progression of both conditions. 

Huibi et al showed that treatment of myopic chick eyes with traces of zinc could inhibit eye axis elongation. Levels of retinal zinc were also greater in normal eyes than myopic eyes. It is known that a lack of zinc increases oxidative stress, and the lack of zinc can result in increased generation of reactive oxygen species (ROS) in the retina. This can feed into the adjacent vitreous, where oxidative stress can promote protein crosslinking and glycation events, resulting in vitreous liquefaction and the formation of floaters.

Some research has hypothesised that the origin of floaters in young people with myopic vitreopathy may also be a result of embryonic remnants in the vitreous, rather than age-related vitreous degeneration, which would help to better explain how some people are affected by floaters from very early ages. 

During the first trimester of pregnancy (from conception to embryo to foetus), the vitreous contains blood vessels, called the foetal hyaloid vasculature, which feed the eye as it grows. In the second trimester of pregnancy, these blood vessels regress and disappear as retinal blood vessels start to grow. 

Studies into how the protein composition of the vitreous changes during this process has led researchers to suggest that people affected by floaters due to myopic vitreopathy will have evidence of incomplete regression of the foetal hyaloid vasculature .

Floaters aren’t the only complications that can arise from the progression of short-sightedness, with increased risk of other sight-threatening conditions being placed on individuals, especially those who are highly short-sighted.

Glaucoma  is a group of eye diseases that can cause vision loss and blindness by damaging the optic nerve in the back of the eye. A systematic review of available evidence concluded that the risk of developing glaucoma was almost 50% greater in high and moderately short-sighted individuals compared to those with low myopia.

Cataracts are caused by the clumping of proteins in the lens resulting in clouded vision. Population studies have shown that short-sightedness is associated with cataract formation, and progression to high short-sightedness associated with an increased risk of cataracts.

Macular degeneration is a condition which causes loss or blurring of your central vision due to damage to the macula, part of your retina. The risk of macular degeneration increases sharply as short-sightedness worsens, particularly as you age . 

At present, there is no way to reverse short-sightedness once it has developed. There are however a number of treatment options that you can consider.

The most common intervention used for short-sightedness is glasses with corrective lenses. Concave prescription lenses will bend light rays slightly outwards to counter the over-focussing propensity and focus light directly on the retina. 

Regular contact lenses do the same job as glasses but sit directly on the surface of the eye, while ortho-k (orthokeratology) are special types of lenses which help temporarily reshape the cornea to improve vision. 

Surgical intervention is an option to correct short-sightedness, with several types of laser eye surgery and lens surgery available. Laser eye surgery involves using a laser to alter the shape of the cornea, while in lens surgery an artificial lens will be put into your eye. 

For more information, The Royal College of Ophthalmologists website provide detailed patient guides about laser eye surgery and lens surgery.

You should have an eye test every 2 years or as often as your optician recommends it. For children, it is often recommended to have a test every year. 

If you notice any changes in your vision, book an eye test as soon as possible. In the UK, the NHS offer free eye tests for certain groups, including children under 18. Particularly for refractive errors, organising a routine eye test with your optician will give you an accurate prescription from which you can discuss the best options for you.

Oxidative stress plays a role in the development of both short-sightedness and eye floaters, but your intake of micronutrients can help prevent oxidative stress and protect your eyes. 

You can increase the amount of antioxidants in your diet by adding more types of fruit and veg, herbs and spices, or using supplements such as Theia Bio’s Clearer^TM which contains potent antioxidants from ingredients such as zinc citrate, lutein, and zeaxanthin. 

Regular exercise is hugely important for your overall health. It can help to promote your body’s anti-oxidative and anti-inflammatory responses, and regulate blood sugar levels, providing great overall protection for your eye health. 

Part of the solution to short-sightedness, according to the World Health Organisation (WHO), comes from encouraging children to spend more time outdoors and less time doing intense ‘near-vision activity’ such as reading or looking at screens. 

Try to limit your screen time as much as you can and spend more time outdoors, but also be mindful to wear sunglasses to protect your eyes from harmful UV rays.

Globally, short-sightedness is becoming an increasingly common issue, which can arise due to a combination of genetic and environmental factors. 

The structural changes that occur as the short-sighted eye lengthens can cause eye floaters to arise as the vitreous structure degenerates, while processes such as oxidative stress can contribute to the development and progression of both eye floaters and short-sightedness.

In isolation, there are a number of ways short-sightedness can be managed, but significant sight-threatening complications such as cataracts or glaucoma can still arise - particularly in those who are highly short-sighted.

While there is little we can do to prevent the condition entirely, maintaining a proactive approach to our eye health will help ensure that you can seek out the best treatment options for you and your family.

Changes to your vision are sometimes unavoidable, so always consult your optician or ophthalmologist if you notice any differences, and be sure to keep up to date with how often your eyes are being tested. 

Also, making small changes to your daily routines, in terms of your diet and activity levels, are an easy way you can make sure you are best protecting the health of your eyes. 

Paying particular attention to how much time your children are spending outdoors and away from intense ‘near-vision activities’ can go a long way to reducing their risk of being significantly affected by short-sightedness.