Myopia, or shortsightedness, is increasing around the world, with many calling it an epidemic. In the US for example the prevalence of myopia has increased markedly in the last 30 years – from 25% in the early 1970s, among those aged 12 to 54 years, to over 40% now. Australia shows similar trends. Aside from the burden of needing spectacles or contact lenses to function normally, patients with myopia have a much higher risk of blinding eye disease later in life. If you would like to know more about the specifics of the treatment options we offer here at Innovative Eye Care to slow the progression of myopia, book an appointment or find out more by giving our friendly staff a call.
For most people the concept of short-sightedness evokes the harmless image of a school-aged child using glasses to see the television and school board clearly. However, around the world the incidence of myopia is becoming worryingly high. There are approximately 1.4 billion people worldwide with myopia, with the prevalence rising to an estimated 2.5 billion by 2020. Studies in Taiwan have shown that 93% of 18 year old girls in the country are myopic. In Singapore, 7 out of 10 college graduates have the condition, and in the most populous country in the world, China, studies have shown rates as high as 78% among 15 year old children residing in urban areas. Statistics show that 30% of Australian high school graduates are myopic, and this percentage is on the rise.
Myopia is associated with the lengthening of the eye. The two most common forms of myopia are youth-onset myopia and adult-onset myopia, depending on the age of diagnosis. Most patients with youth onset myopia (<20 years of age) tend to have more aggressive myopia progression and will continue to become more and more short-sighted over time until their eye stops growing. Adults that develop myopia can also progress over time. Patients with myopia will be highly dependent on more expensive, high-powered glasses or contact lenses for any visual tasks. They may also have to keep updating their prescription lenses each year as their eye becomes more shortsighted.
Out of context the implication of myopia can be hard to grasp. Studies show us that the risk factor for eye disease due to any degree of myopia is comparable with the risks of cardiovascular disease associated with untreated high blood pressure. The myopia risks for glaucoma and cataract were also comparable with the risks of stroke from smoking >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.
More concerning is that all levels of myopia increase the chance of blinding conditions such as retinal detachment, cataracts, glaucoma and myopia retinal degeneration later in life. These conditions are far from rare: myopia maculopathy, a progressive condition causing breakdown of retinal cells, is the forth most common cause of visual impairment in the UK, ahead of diabetic eye disease.
The risk of these conditions is much higher as the degree of myopia increases. An Australian study showed myopes of less than 5 Dioptres (low 'phyiological' myopia: an arbitrary cut-off that was previously thought to represent a 'safe' level of myopia) had a myopic retinopathy prevalence of 0.42% as compared to 25.3% for myopes with greater than 5 Dioptres of myopia (high 'pathological' myopia). This represents a 60 fold increase in risk for higher myopic patients. The life chance of a retinal detachment in patients with more than 5 Diopters of myopia is around 5% as shown in a recent study, whereas this risk is 0.3% for the general population.
An important concept to re-iterate is that 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. If we can stop the progression of myopia into these high levels then a significant amount of blindness can be prevented. Studies suggest that even a modest reduction in the rate of myopia of 33 % could produce a 73 % reduction in myopia above 5.00 D.
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 -7.50D 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, these were able to be repaired 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.
CAPTION: The appearance of Alex's eye after his retinal detachment surgery (left) and some of the retinal scar left after surgery in Alex's eye (right). This peripheral part of his vision is now permanently blind.
Prescribing standard spectacle lenses or contact lenses will do nothing to halt the progression of shortsightedness. As a result, the patient will require frequent spectacle lens updates and will be put at risk of sight-threatening problems in the future. Unfortunately, the lengthening of the eye which causes myopia cannot be reversed, making it critical to control myopia sooner rather than later.
The good news is, there is convincing evidence that certain treatments can slow and even halt the progression of myopia. Orthokeratology and topically administered atropine drops have been shown to be the two most effective tools currently available to control myopia. These are not for every patient, so it is necessary to determine an appropriate treatment plan with your optometrist. Other treatment options do exist, though they do not show the same level of myopia control.
CAPTION: Myopia control can slow progression by 50% and lower risk of blindness
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 reshapes the surface of the eye, giving clear vision the next day without the lenses. As well as being convenient for the patient, the treatment actually slows and in some cases stops myopia progression. When myopic eyes are corrected with conventional spectacles and contact lenses, light entering the eye centrally will focus at the retina; however, light entering off-centre will focus behind the retina. This is thought to stimulate lengthening at the back of the eye as the retina tries to reach the focal point behind the eye, worsening the condition. Ortho-K lenses can slow this growth by changing the shape of the eye surface, allowing central light to focus accurately at the retina and off-centre light to focus in front of the retina. The retina will no longer 'attempt' to elongate.
Research has now shown a range of 32%-100% slowing of myopia progression depending on the study. Most reports suggest an average of a 50% reduction in the rate of myopia progression with ortho-K contact lens wear. Results in our practice and from other myopia control practices in Australasia show complete halting of myopia progression in some patients.
Atropine drops have been used for many years to control myopia; however, until recently they have been prescribed at a normal concentration of 0.5% - 1%. Atropine at this concentration causes loss of focusing in young children for near tasks and dilates the pupil leading to light sensitivity. For young patients that show aggressive myopia progression we will still recommend 1% atropine in order to best control their myopia progression. These drops are used in conjunction with tinted transitions progressive lenses to give protection from bright light and the ability to see for reading tasks.
Studies over the last decade have found that much lower concentrations of atropine, such as 0.02%, have a comparable reduction in myopia progression, without any noticeable effect on pupil size or near-focusing. For example the ATOM2 study showed the myopia control effect of 75% reduction for the 1%, 0.5% and 0.1% concentrations and 65% reduction with 0.01%. Studies have told us that 0.02% is the highest concentration of atropine that shows no significant change to near focussing or pupil size in children, and has no reported allergic side effects.
It was initially thought that as atropine drops paralyse the focusing muscles of the eye, this was the reason for the myopia control. Our understanding now suggests that the atropine molecule affects a receptor in the choroid or sclera of the eye (the vascular and structural layers of the eyeball), signalling to the eye not to elongate excessively. This mechanism is still being studied around the world.
Atropine drops need to be instilled nightly and can be combined with Ortho-K therapy to maximise the myopia control effect. Visual and general side-effects are highly unlikely at 0.02%. Atropine drops will need to be specially formulated at a compounding pharmacy as they are not readily available at concentrations below 0.5%.
Certain types of soft contact lenses have been used to try to control myopia, although results have been underwhelming. Multifocal soft contact lenses are typically used by patients in their fifth decade of life onwards to improve their near vision. These have a similar peripheral area of steepening on the lens like Ortho-K, although at a lower level (maximum +3D, whereas the above ortho-K example shows a +8D difference!). As a result, when these soft contacts have been used by young patients, studies have only reported a modest range decreased progression of 29-45% . Specialised soft contact lenses called MiSight (Coopervision) have been designed by a research team in New Zealand specifically with myopia control in mind, and have been TGA approved for the indication of controlling myopia progression. These lenses show a 40% reduction in myopia progression. 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.
As mentioned previously, normal spectacles offer no myopia control benefit. In some individuals that are already progressing myope and patients that show a near esophoria (tendency for their eyes to turn in more than required when reading) or an accomodative lag (a child's eyes do not focus enough on a near task they are looking at) then progressive addition spectacles lenses (normally used for older patients who cannot focus on near print) may offer some myopia control benefit. The near conditions mentioned above are tested by your optometrist during their appointments. Studies are varied but suggest a reduction of myopia progression in the range of 12-55% with these lenses.
Myovision spectacle lenses are specially designed for controlling myopia but studies suggest they only slow progression by 0-30%. As a result they are infrequently used. The 30% figure was for children aged 6-12 years with a history of parental myopia.
As well as the above treatments, there is some evidence that spending at least 2 hours a day outside in the sun may decrease the rate of myopia progression. The mechanism of action is not understood but the effect size is robust.
There is an excellent website by Richard Anderson (myopiaprevention.org) which explains in detail all aspects of myopia control with the relevant research included.
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 to discuss their myopia and what may be done to arrest this progression.
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