Myopia, or shortsightedness, is a common condition where the main symptom is blurred distance vision. This occurs because the focusing power of the eye is too strong or (more commonly) the length of the eye is too long. While blurry distance vision can be corrected with spectacles or contact lenses, the real issue is the structural changes at the back of the eye which increases the risk of irreversible eye disease. 1,2 The higher the level of myopia, the higher the risk.
Our optometrists offer a wide range of treatment options to slow the progression of myopia. If you would like to find out more, book an appointment at our Adelaide or Woodville practices or speak to our friendly staff.
In myopic eyes, light is focused in front of the retina rather than on it, causing blurry distance vision. This usually occurs because the eye is physically too long. Myopia is a progressive condition, meaning over time the eye continues to grow longer, increasing the level of myopia. As the eye grows, the tissues at the back of the eye become stretched. People with high levels of myopia are at an increased risk of irreversible eye disease (e.g. retinal detachments and glaucoma).1,2 Myopia can develop at any age but the younger the onset the higher the risk of progression to high myopia.
As kids grow so do their eyes. Normally our eyes keep growing until the age of 14, after which it stabilizes.3 However, in myopic eyes this normal growth pattern is interrupted and the eye continues to grow exponentially resulting in progressive myopia.3
The prevalence of myopia is increasing drastically, with the World Health Organisation considering it an epidemic. Currently, 30% of the Australian population is myopic and it is estimated that by 2050 half of the worlds population will be myopic.4 Myopia tends to manifest in children, with the average age of onset being 8 years old5, 6, however it has recently been discovered that 30% of myopic people develop myopia after the age of 17!
There are two main risk factors for developing myopia; lifestyle and family history. If one or both parents are myopia, then the likelihood of a child developing myopia is increased. 7 While you can’t choose your parents, you can choose your lifestyle! Modern lifestyles of urban environments, such as low levels of outdoor activity, low light exposure and prolonged near tasks have been shown to increase the development of myopia. 6, 7, 8
Historically, low myopia was considered a normal variation of the eye. Now there is a clear distinction between the two types of myopia:
The main difference between low and high myopia is the association with eye growth, or axial length. The best way to assess the risk of eye disease from myopia is to measure axial length and monitor the change over time. Due to the structural changes that occur at the back of the eye, once the axial length exceeds 26.5mm, the risk of eye disease such as glaucoma and retinal detachment is significantly increased.2 This is why slowing down the progression of myopia is so important.
A study published in 20121 on the interactions of several factors on myopia found the following:
“Myopia in the so-called ‘physiological range’ represents a major risk factor for ocular disease that is comparable with the risks associated with hypertension for cardiovascular disease or with the risks of stroke from smoking more than 20 cigarettes per day. For retinal detachment and myopic maculopathy, myopia carries a risk far in excess of any identified population risk factor for cardiovascular disease.”These conditions are far from rare: myopic maculopathy, a progressive condition causing irreversible damage to the retina, is the 4th most common cause of visual impairment in the UK, ahead of diabetic eye disease.7 While the risks of eye disease later in life are present for any degree of myopia, the higher the amount of myopia, the higher the risk. The risk of permanent vision loss in patients with axial length longer than 26mm is 25%, compared to 3.8% in eyes less than 26mm.2 If we can stop the progression of myopia into these high levels then a significant amount of blindness can be prevented.
The personal case of one of our previous optometrists, Alex Petty, highlights why myopia control is so important. Alex developed myopia at the age of 9. This progressed throughout his teenage years, eventually stabilising at a high -7.50 D in each eye. As a result, Alex suffered two retinal detachments in his left eye in 2009 and another in 2014 in his right. Fortunately, through timely surgery the damage was controlled with only slight vision loss.
If Alex had access to myopia control treatments when he was a teenager, it is unlikely his prescription would have worsened as quickly and these ocular emergencies might have been prevented. His experience has fuelled a passion to treat young people with myopia and prevent eye disease later in their lives.
Standard spectacle or contact lenses will make the distance vision clear but will do nothing to stop the lengthening of the eye or decrease the risk of permanent eye disease. While myopia cannot be cured or reversed, we can slow down and even stop its progression, making early detection and intervention critical. Current evidence shows that orthokeratology, atropine eye drops and multifocal contact lenses are the most effective tools to control myopia.
To find out more, make an appointment with one of our optometrists.
Orthokeratology (or ortho-K) is a type of contact lens wear which has been practiced at Innovative Eye Care for many years. Ortho-K involves wearing a custom-designed contact lens overnight which reversibly and temporarily reshapes the cornea (front surface of the eye) while you sleep, providing clear vision the next day without the need for spectacles or contact lens wear during the day.
As well as being convenient, ortho-K actually slows and in some cases stops myopia progression.8,9,10 Ortho-K has been proven to slow myopia progression by 32-100%, depending on the study.8,9,10 Results in our practice and from other myopia control practices in Australasia show complete halting of myopia progression in some patients.
Atropine is a prescription eye drop that has been used for many years to control myopia. It is thought to interact with receptors in the eye that control growth in order to slow myopia progression.10,11 There are different concentrations of atropine available, and evidence has shown that the effect on myopia control is a dose dependent relationship. Meaning, the higher the concentration, the greater the effect on slowing down axial length growth.10,11,12 For young patients that show aggressive myopia progression we recommend higher concentrations of atropine.
Atropine drops need to be taken every night and in some cases can be combined with ortho-K lenses to maximise the myopia control effect. Visual and general side-effects are unlikely to occur at low concentrations of 0.02%, however can occur at higher concentrations. Side effects may include glare symptoms due to dilated (larger) pupils or difficulty focusing up close. These side effects are reversible upon cessation and have not shown to cause any long term changes.12
Atropine drops will need to be specially formulated at a compounding pharmacy as they are not readily available at concentrations below 0.5%. To find out more about atropine and the different options suitable for you or your child, make an appointment at our Adelaide or Woodville practice.
Certain types of soft contact lenses have been used and developed to control myopia. Multifocal soft contact lenses are typically used by people over 40 to improve their near vision. These have a similar lens curve and pattern to ortho-K. As a result, when these soft contacts have been used by young patients, studies show an average of 38% decrease in axial length growth.10
Specialised soft contact lenses called MiSight (Coopervision) show a 40% reduction in myopia progression.10,13 If ortho-K lenses are not suitable, these soft contact lenses may be discussed by your optometrist as an alternative option, and may be used in conjunction with atropine drops.
Regular spectacles, although make distance vision clear, offer minimal myopia control benefit. Some spectacles that incorporate specialised designs, such as the Miyosmart lens, have been clinically proven to be effective in slowing down myopia progression. The Miyosmart lens incorporates Defocus Incorporated Multiple Segments (DIMS) technology that provides both clear vision and the benefit of slowing axial length growth by 60%.14 This lens will be available in Australia as of October 2020.
In myopic individuals that have an accommodative lag (decreased ability to focus up close), bifocal spectacle lenses may reduce myopia progression by up to 30%.15 The accommodative (focusing) system is tested by your optometrist during your appointment to find the best option for you.
Apart from active interventions, there is also sufficient evidence for the modification of lifestyle factors of time spent on near work and time spent outdoors. More time spent outdoors in natural light can delay the onset and perhaps reduce progression of myopia. There is also evidence that excessive near work increases the risk of myopia.3
There is an excellent website by Richard Anderson (myopiaprevention.org) which explains in detail all aspects of myopia control with the relevant research included.
Axial eye length is the best metric of risk and progression for myopia. It has the least variability and directly relates to the disease processes that myopia can create. If you are concerned about your child’s eyes becoming progressively short-sighted, please contact our friendly team to arrange a consultation with one of our optometrists.