tag:theconversation.com,2011:/ca/topics/eye-glasses-986/articlesEye glasses – The Conversation2021-11-25T04:21:36Ztag:theconversation.com,2011:article/1718262021-11-25T04:21:36Z2021-11-25T04:21:36ZWhat is orthokeratology? And will it help slow the deterioration of my child’s eyesight?<figure><img src="https://images.theconversation.com/files/432109/original/file-20211116-21-1fbmxqn.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C2443%2C1616&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>If you or your child is short-sighted (struggles to see things further away) you might have heard about orthokeratology. </p>
<p>Also known as OK or ortho-k, orthokeratology has been around since the 1960s. However, it has gained interest recently for its ability to slow the progression of myopia (short-sightedness).</p>
<p>Orthokeratology involves wearing a specially-designed rigid contact lens overnight. Like a mold, the lens temporarily reshapes the eye while you sleep by gently changing the profile of the cornea (the eye’s clear, protective outer layer that acts like a powerful lens).</p>
<p>This creates a temporary change; when you wake up, you take the lens off and voilà! You can see.</p>
<p>It takes about a week of going through the cycle for the full effect to be reached but after that – assuming you wear them every night and take them off every morning – you should be able to get through your days without glasses or contact lenses. </p>
<p>And most importantly, there’s good evidence it can help slow the progression of myopia.</p>
<p>Like all treatments, however, orthokeratology has its pros and cons – and its risks need to be well understood before use. </p>
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<strong>
Read more:
<a href="https://theconversation.com/hidden-in-plain-sight-how-the-covid-19-pandemic-is-damaging-childrens-vision-158737">Hidden in plain sight: How the COVID-19 pandemic is damaging children’s vision</a>
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<a href="https://images.theconversation.com/files/432114/original/file-20211116-25-1tk03qz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/432114/original/file-20211116-25-1tk03qz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/432114/original/file-20211116-25-1tk03qz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432114/original/file-20211116-25-1tk03qz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432114/original/file-20211116-25-1tk03qz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432114/original/file-20211116-25-1tk03qz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432114/original/file-20211116-25-1tk03qz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432114/original/file-20211116-25-1tk03qz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The orthokeratology lens temporarily reshapes the eye while you sleep.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>The pros</h2>
<p>Orthokeratology may be an appealing option:</p>
<ul>
<li><p>for people who want an alternative to glasses but find contact lenses either uncomfortable or not suitable (because, for example, they suffer from <a href="https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/dry-eye">dry eye</a>, work in dusty environments or enjoy water sports)</p></li>
<li><p>as an alternative to refractive surgery, also known as laser eye surgery or LASIK. Refractive surgery is permanent but orthokeratology is temporary; if you stop using the lenses, things go back to normal within a week</p></li>
<li><p>for parents of a child who might otherwise be wearing contact lenses at school; ortho-k allows a child to go to school without glasses or contact lenses, which can be lost or come loose during the day.</p></li>
</ul>
<h2>The cons</h2>
<p>The potential downsides include:</p>
<ul>
<li><p>the up-front costs are higher than daily wear contact lenses where the similar overall cost is spread over time</p></li>
<li><p>the effect wears off if you don’t use them every night</p></li>
<li><p>all contact lens use comes with a higher risk of eye infection than if you had no contact lenses at all.</p></li>
</ul>
<p>Some people might think orthokeratology has a higher infection risk than standard soft contact lenses. However, this is not supported by the research evidence. </p>
<p>A <a href="https://onlinelibrary.wiley.com/doi/10.1111/opo.12460">study in Japan</a> compared outcomes after 10 years of wear in children of either orthokeratology or soft contact lenses. It found there were no severe adverse events and the frequency of mild and adverse events were about equal between the groups. </p>
<p>If you get an infection from either a standard contact lens or orthokeratology lenses, it usually clears up with a course of antibiotics. However, it’s possible to get a rare infection called microbial keratitis, which has the potential to damage sight.</p>
<p>It’s not common. According to one <a href="https://journals.lww.com/optvissci/Abstract/2013/09000/The_Risk_of_Microbial_Keratitis_With_Overnight.6.aspx">study</a>, if you were to wear an orthokeratology lens every night for 1,000 years you are only likely to get one serious infection. </p>
<p>If you use sterile contact lens solutions and avoid tap water, orthokeratology lens-wearers will dramatically reduce their risk of eye infection. Tap water exposure to lenses or lens accessories greatly <a href="https://iovs.arvojournals.org/article.aspx?articleid=2124094">increases the risk of infection</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/432111/original/file-20211116-25-1fqf1ts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A girl gets her eyes tested." src="https://images.theconversation.com/files/432111/original/file-20211116-25-1fqf1ts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/432111/original/file-20211116-25-1fqf1ts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432111/original/file-20211116-25-1fqf1ts.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432111/original/file-20211116-25-1fqf1ts.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432111/original/file-20211116-25-1fqf1ts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432111/original/file-20211116-25-1fqf1ts.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432111/original/file-20211116-25-1fqf1ts.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Slower myopia progression also means less frequent need for replacing glasses, which can save you money in the long run.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<h2>Reducing risk of devasting eye disease later in life</h2>
<p>It’s now projected <a href="https://www.aaojournal.org/article/S0161-6420(16)00025-7/fulltext">half the world’s population will by myopic by 2050</a>, and the World Health Organization has sounded the alarm, saying in one <a href="https://www.who.int/bulletin/volumes/98/6/19-240903.pdf">bulletin</a>:</p>
<blockquote>
<p>High myopia greatly increases the risk of macular atrophy, glaucoma and
other causes of severe vision loss, the incidence of which is not reduced by
wearing standard glasses.</p>
</blockquote>
<p>Slowing the progression of myopia reduces <a href="https://theconversation.com/hidden-in-plain-sight-how-the-covid-19-pandemic-is-damaging-childrens-vision-158737">risk of sight-threatening eye disease</a>. It also means less frequent changes in vision, which can save money in the long run from needing fewer changes to glasses.</p>
<p>Myopia progresses <a href="https://journals.lww.com/optvissci/Abstract/2012/01000/Myopia_Progression_Rates_in_Urban_Children_Wearing.7.aspx">faster in younger years</a>, so a myopia control prevention should be prescribed as early as possible. We don’t know exactly how orthokeratology slows myopia progression, but compelling <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0124535">research</a> shows it does.</p>
<p>If you’re considering orthokeratology for your child, you and your eye specialist need to strike a balance. The child must be old enough to be handle it – but wait too long and the the myopia control benefits it offers diminish. </p>
<p>Every child is different. Some are more able than others to contend with orthokeratology, or willing to wear it overnight. It can be uncomfortable at first, and some might find the idea of a contact lens too confronting. It cannot be forced.</p>
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<a href="https://images.theconversation.com/files/432113/original/file-20211116-13-1j6celv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/432113/original/file-20211116-13-1j6celv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/432113/original/file-20211116-13-1j6celv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432113/original/file-20211116-13-1j6celv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432113/original/file-20211116-13-1j6celv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432113/original/file-20211116-13-1j6celv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432113/original/file-20211116-13-1j6celv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432113/original/file-20211116-13-1j6celv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Too much ‘close work’ can make myopia worse in children.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Review all the options</h2>
<p>Orthokeratology isn’t the only solution; there are also special lenses you can get for glasses and soft daily wear contact lenses that help slow progression of myopia. Seek advice from eye specialists to to review all the options. </p>
<p>I also recommend children do no more than two hours per day of leisure “close work” (meaning non-school work: close up screen time or book-reading) outside school hours. Parents can also teach kids the “<a href="https://www.mykidsvision.org/blog/the-visual-environment/">20-20 rule</a>” (for every 20 minutes of close work, take a 20 second break to look into the distance). Outside time (<a href="https://www.mdpi.com/1660-4601/16/14/2595">two or more hours per day</a>) is also crucial to healthy eye development in children.</p>
<p>What’s clear, however, is that all short-sighted children should be doing something to control their myopia. It’s not enough just to give a child standard single vision glasses to help them see, without doing more to help slow the march of myopia.</p>
<p>If right for your child, orthokeratology has one of the strongest research pedigrees for slowing progression of myopia.</p>
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<strong>
Read more:
<a href="https://theconversation.com/how-to-keep-your-contact-lenses-clean-and-what-can-go-wrong-if-you-dont-141117">How to keep your contact lenses clean (and what can go wrong if you don't)</a>
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<img src="https://counter.theconversation.com/content/171826/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Gifford is an Adjunct Senior Lecturer at the University of New South Wales and Adjunct Associate Professor at the University of Waterloo, Canada. He is co-founder of Myopia Profile, which educates optometrists and companies on research relating to vision, and MyKidsVision.org which provides parent focused research backed information on managing childhood myopia.</span></em></p>Orthokeratology involves wearing a specially designed rigid contact lens overnight. There’s good evidence it can help slow the progression of myopia. But like all treatments, there are risks, too.Paul Gifford, Adjunct Senior Lecturer, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1115992019-02-12T22:48:25Z2019-02-12T22:48:25ZToo much screen time linked to an epidemic of myopia among young people<figure><img src="https://images.theconversation.com/files/258623/original/file-20190213-90497-18zyb99.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Today’s young people don’t play outside as much as their predecessors and are heavy users of electronics.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Ask anyone about the benefits of technology and it probably won’t take them long to rhyme off a list of examples: it helps broaden your knowledge, connect with friends, both new and old, and allows you to see things you’ve never seen before.</p>
<p>But what about the drawbacks? Here’s a major one: increased screen time is hard on your eyes.</p>
<p>In fact, more and more young people are wearing glasses to correct their nearsightedness. This trend has prompted optical health experts to determine if the use of electronic devices such as computers, tablets and smart phones is leading to a deterioration in sight that is reaching epidemic proportions.</p>
<p>Let’s take the example of Pauline — although she could just as easily be a David or a Jason. She is 10 years old and a studious child, doing well in school. Like any young person her age, she loves to use her tablet computer to study or have fun. She’s on it two hours a day, plus weekends.</p>
<p>Pauline may be in for a change, however. She has recently been diagnosed with nearsightedness and her optometrist has strongly recommended that she — and her parents — limit her use of electronic devices and spend more time playing outside.</p>
<p>Pauline isn’t happy. She thinks it’s not fair.</p>
<p>But her case raises the question: what is the link between the use of electronic devices and the appearance of myopia?</p>
<h2>A public health issue</h2>
<p>Forty per cent of North Americans are affected by myopia. The number of cases <a href="https://www.ncbi.nlm.nih.gov/pubmed/18695106">doubled between 1972 and 2004</a> and continues to grow at a rate that <a href="https://www.ncbi.nlm.nih.gov/pubmed/24357836">qualifies the phenomenon as an epidemic</a>.</p>
<p>In Europe, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4504030/#sec2title">myopia is prevalent among 42.2 per cent of adults aged 25 to 29 years</a>, almost twice that of adults aged 55 to 59 years.</p>
<p>This suggests there is a real public health issue facing us — and not just the common problem of an error in the refraction of the eye which shows up as blurred vision when looking into the distance.</p>
<p>In fact, high amounts of myopia <a href="https://www.ncbi.nlm.nih.gov/pubmed/22772022">significantly increases the risk of major ocular health disorders </a>such as retinal tearing (21 times greater), glaucoma (40 times) or cataracts (six times).</p>
<p>An eye that becomes short-sighted becomes longer. The stretching is proportional to <a href="https://www.ophthalmologymanagement.com/issues/2012/july-2012/measuring-axial-length">the increase in myopia</a>. The more the eye stretches, the more the retina, which lines the inside of the eye, becomes thinner. Symptoms such as cracks, abnormal development of subretinal blood vessels and bleeding may appear.</p>
<p>Ultimately, the very nearsighted patient has a more than 50 per cent risk of spending the rest of his or her life legally blind — in other words living with vision reduced by 60 per cent. This means that the <a href="https://www.ncbi.nlm.nih.gov/pubmed/20363029">length of their eye exceeds 28 mm</a> (the normal length is 23 mm) or that <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=Tideman+JAMA+ophthalmol">the myopia levels exceeds six diopters</a>. (Diopters is a unit of measurement used to calculate eyesight — the further away from zero indicates a worsening in vision.) It is important to intervene before this happens to avoid these levels.</p>
<p>(In Canada, <a href="https://www.epso.ca/vision-health/general-interest/legal-blindness/">legal blindness is defined by a visual acuity of less than 20/200 </a>in the best eye with the help of glasses or contact lenses. A legally blind person therefore sees, at best, 20 times worse than a person with normal acuity.)</p>
<h2>What’s behind the epidemic?</h2>
<p>There are many causes of onset myopia. Genetics plays an important role but epigenetics — the environment in which the child evolves — is <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=Rong+Asia+Pacific+Pacific+J+Ophthalmol">a more important factor</a>.</p>
<p>And what has changed in our environment to explain the recent myopia epidemic? The impact of technology, which has seen a boom in recent years, is being closely examined.</p>
<p>For example, a rapid increase in visual problems has been noted since the introduction of the smartphone in 2007. While the device itself does not emit harmful radiation, it requires the user to read its screen at a distance of 20 cm rather than the normal distance of 45 cm to 50 cm. It has been suggested that this close distance <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4473431/">boosts the risk of developing myopia by eight times</a>, especially if both parents are myopic.</p>
<p>Ambient lighting also plays a role because <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4526691/">the use of fluorescents</a>, such as in classrooms, also promotes myopia. When a tablet is used in such an environment, the effect is multiplied tenfold.</p>
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<img alt="" src="https://images.theconversation.com/files/252534/original/file-20190104-32142-2rkjfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/252534/original/file-20190104-32142-2rkjfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=303&fit=crop&dpr=1 600w, https://images.theconversation.com/files/252534/original/file-20190104-32142-2rkjfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=303&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/252534/original/file-20190104-32142-2rkjfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=303&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/252534/original/file-20190104-32142-2rkjfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=380&fit=crop&dpr=1 754w, https://images.theconversation.com/files/252534/original/file-20190104-32142-2rkjfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=380&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/252534/original/file-20190104-32142-2rkjfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=380&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Unlike paper books, tablet and computer screens emit blue light. The short wavelengths from blue light are perceived in front of the others by the eye, which generates a myopia stimulus.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Unlike books printed on paper, tablet and computer screens are optically associated with so-called chromatic aberrations. The shortest wavelengths (blue light) are perceived in front of the others by the eye, which generates a myopia stimulus. There is a dose and response effect here, suggesting that prolonged use leads to more negative effects.</p>
<p>Today’s young people don’t play outside as much as their predecessors and are heavy users of electronics. However, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3474591/">exposure to daylight has a protective effect against myopia</a>. These beneficial effects are decreased, but not negligible, <a href="https://www.ncbi.nlm.nih.gov/pubmed/30288926">during less sunny months</a> or when <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5599950/">myopia is already present</a>.</p>
<h2>Possible solutions</h2>
<p>The purpose of myopia treatment is to reduce the rate of progression of the dioptric, but above all to slow down the elongation of the eye. If, obviously, we cannot play with genetics, it is imperative to influence epigenetics and therefore the environment in which the child evolves.</p>
<p>Therefore, using any electronic media before the age of two should be avoided, <a href="http://pediatrics.aappublications.org/content/pediatrics/early/2011/10/12/peds.2011-1753.full.pdf">even if it’s only for a few minutes</a>. A limit of one hour per day should be the rule for those between two and five years of age and the emphasis should be put on educational sites or applications that promote interactions between the parent and child.</p>
<p>While school requests should be taken into consideration, the use of electronic media should continue to be limited as the child gets older. A maximum of one hour, besides school work, must be observed for good eye health. A two-minute break after every 30 minutes of device use will also lessen harmful effects and <a href="https://bmjopen.bmj.com/content/5/1/e006748">exposure to a device should be avoided at least one hour before sleep.</a></p>
<p>Children should also get a minimum of 45 minutes of daylight per day. They can get this by walking to school or participating in such activities as regular outdoor sports.</p>
<p>The next step is to ensure the co-ordination of both eyes, from far away but especially close up. An optometrist will need to perform an orthopic check-up and correct, by exercise or optical means, any anomaly that may have been detected.</p>
<p>Finally, optical correction must be chosen with the goal of slowing down the progression. In rare cases, glasses with anti-myopia lenses may be prescribed. They provide a <a href="https://www.ncbi.nlm.nih.gov/pubmed/26826749">deceleration rate of about 30 per cent </a>. Specialized contact lenses are often preferred and offer control ranging from 50 per cent to 80 per cent. The contact lens treatment is available from the age of seven, and will be periodically reassessed according to the child’s changing needs.</p>
<p>In short, myopia is not just a commonplace vision defect. It is a significant risk factor for serious eye disease. We must therefore do everything possible to slow its progress and protect our children’s vision — and that means also reviewing their relationship with electronic devices.</p><img src="https://counter.theconversation.com/content/111599/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Langis Michaud has received funding from: Johnson and Johnson, Bausch and Lomb, Cooper Vision and is a member of l'Association des Optométristes du Québec.</span></em></p>Myopia is a major risk factor for serious eye diseases. It has become epidemic among children, particularly because of their heavy use of electronic devices.Langis Michaud, Professeur Titulaire. École d'optométrie. Expertise en santé oculaire et usage des lentilles cornéennes spécialisées, Université de MontréalLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/843632018-01-21T19:14:56Z2018-01-21T19:14:56ZCurious Kids: How do glasses help you see?<figure><img src="https://images.theconversation.com/files/201871/original/file-20180115-101495-1uqhel4.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Glasses help people to see by focusing light onto the retina.</span> <span class="attribution"><span class="source">Marcella Cheng/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em> </p>
<hr>
<blockquote>
<p><strong>How do glasses help you see? – Andy, age 5, Vincentia.</strong> </p>
</blockquote>
<hr>
<p>Hi Andy, and thank you for your question about glasses.</p>
<p>You’ve asked this at a very good time because more and more people are needing to wear glasses, including young children, and we don’t really know why.</p>
<p>Our eyes let us see because light enters each eye, and the eye then creates a message that goes to the brain. </p>
<p>The eyeball itself doesn’t actually “see” – the brain sees. The eyeballs just take pictures, like two little cameras. To see properly, each eyeball needs to send the light that enters it onto a very exact spot inside the eyeball, called the retina. If the light falls onto the wrong place, your vision will be blurry. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/190301/original/file-20171016-27729-1ckp1fz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/190301/original/file-20171016-27729-1ckp1fz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/190301/original/file-20171016-27729-1ckp1fz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/190301/original/file-20171016-27729-1ckp1fz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/190301/original/file-20171016-27729-1ckp1fz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/190301/original/file-20171016-27729-1ckp1fz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/190301/original/file-20171016-27729-1ckp1fz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Both shortsighted and farsighted people need glasses to help them see clearly.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Refraction_through_glasses_090306.jpg">Wikimedia Commons/Hackfish</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Many people don’t need glasses and can see just fine. This is because their eyeballs are focusing light properly onto the retina. </p>
<p>However, some people have eyeballs that are too long. They are called “shortsighted”. For these people, things far away, like street signs or the classroom blackboard, can look blurry. </p>
<p>Other people have eyeballs that are too short. They are called “farsighted” and things close to them, like a book or a mobile phone, can look blurry. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-is-the-sky-blue-and-where-does-it-start-81165">Curious Kids: Why is the sky blue and where does it start?</a>
</strong>
</em>
</p>
<hr>
<p>Both shortsighted and farsighted people need glasses to help them see clearly.</p>
<p>They work by helping the eyeball to focus light onto the correct place, the retina. Only then can the eye see clearly.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/201897/original/file-20180115-101508-dsnwd8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/201897/original/file-20180115-101508-dsnwd8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/201897/original/file-20180115-101508-dsnwd8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=476&fit=crop&dpr=1 600w, https://images.theconversation.com/files/201897/original/file-20180115-101508-dsnwd8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=476&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/201897/original/file-20180115-101508-dsnwd8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=476&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/201897/original/file-20180115-101508-dsnwd8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=598&fit=crop&dpr=1 754w, https://images.theconversation.com/files/201897/original/file-20180115-101508-dsnwd8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=598&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/201897/original/file-20180115-101508-dsnwd8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=598&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">They work by helping the eyeball to focus light onto the correct place, the retina.</span>
<span class="attribution"><span class="source">Marcella Cheng/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Maybe you have a grandma or grandpa who wears glasses whenever they are reading books or using their mobile phone. When people get older, they usually become a little bit farsighted because a part of their eye called the lens becomes stiff and doesn’t work properly.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/190299/original/file-20171016-27711-1328oyb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/190299/original/file-20171016-27711-1328oyb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/190299/original/file-20171016-27711-1328oyb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/190299/original/file-20171016-27711-1328oyb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/190299/original/file-20171016-27711-1328oyb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/190299/original/file-20171016-27711-1328oyb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/190299/original/file-20171016-27711-1328oyb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">More and more people, including young children, are needing to wear glasses.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/timomcd/3736541170/in/photolist-6GbKvC-5rc3NK-Xuf4vh-7xrNRs-cGzGdj-p8Q72J-T8FEdG-6ugcGh-aiPJBH-SovhJw-nkyk3R-8vBVVr-YAoiQ9-4y59S3-hWDbFP-9K2q1j-xbsf5q-UWXexK-hZ4qt8-dqrh9U-hXHbRq-jjQzky-4pA5Qg-58qL1f-382MiA-zNH8MF-7PjNjo-pnr2Bn-9iBkty-hW1q3H-mfgj32-paQj9d-58ySbD-hMdpY-ao6xHH-9j4qnh-hVRcEK-nigszh-hXVQoz-oTo4nT-fAiAQt-hXdHw9-aPfTfD-hXodH9-cDhbR9-ehRK4Q-cDhbH3-aiZZX2-ii64MC-oTnV7L">Flickr/Ryan McDonough</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>More and more young people in the world are needing to wear glasses.</p>
<p>We’re not sure why, but some scientists think that children who spend too much time inside are more likely to need glasses. We don’t know if it’s because they aren’t getting enough sunlight or if they’re simply reading too much or playing too many video games when they get home. </p>
<p><a href="https://www.nature.com/news/the-myopia-boom-1.17120">Most children in China are shortsighted</a> and need glasses to see things far away. The Chinese government is so worried about this that they are making sure all students spend some time outdoors instead of just being inside the classroom.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-can-prevent-an-epidemic-of-short-sighted-kids-with-more-time-outdoors-44595">We can prevent an epidemic of short-sighted kids with more time outdoors</a>
</strong>
</em>
</p>
<hr>
<p>Glasses can cost lots of money, and children who need glasses but don’t wear them don’t do as well in school. Once you need glasses, you usually need them forever - your eyes won’t go back to normal on their own. </p>
<p>I hope that one day we can find out why people’s eyeballs become too long or too short and then we can stop people needing to wear glasses in the first place. Then people will never lose or forget their glasses ever again!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/201911/original/file-20180115-101495-13e0tfv.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/201911/original/file-20180115-101495-13e0tfv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/201911/original/file-20180115-101495-13e0tfv.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=499&fit=crop&dpr=1 600w, https://images.theconversation.com/files/201911/original/file-20180115-101495-13e0tfv.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=499&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/201911/original/file-20180115-101495-13e0tfv.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=499&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/201911/original/file-20180115-101495-13e0tfv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=627&fit=crop&dpr=1 754w, https://images.theconversation.com/files/201911/original/file-20180115-101495-13e0tfv.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=627&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/201911/original/file-20180115-101495-13e0tfv.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=627&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When people become older, they usually become a little bit farsighted because a part of their eye called the lens becomes stiff and doesn’t work properly.</span>
<span class="attribution"><span class="source">Marcella Cheng/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<hr>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/84363/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Yosar does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Many people, from children to the elderly, wear glasses. Andy, age 5, wants to know how they work.Jason Yosar, Associate Lecturer, School of Medicine, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.