<!DOCTYPE html><html><head></head><body style="margin: 0px; background-color: white;" ><div id='sa-content-div-pSdBShew0A' style="position: relative; display:inline-block"><div style="position:absolute; top:0; right:0; background:white; opacity:0.7; width:17px; height:15px; text-align:center; z-index: 16777270"><img id='sa-adchoices' src="https://creative.stackadapt.com/icons/adchoices/adchoices.png" width="12" height="12"></div><script>try{var sa_adchoices = document.getElementById('sa-adchoices');if (sa_adchoices){sa_adchoices.onclick = function(){window.open('https://www.stackadapt.com/privacy-policy','_blank');}}}catch(err){console.log(err);}</script><!-- This creative was designed by StackAdapt's creative templates Builder; {SA_CUSTOM_CLICK_TRACK} --><iframe src="https://display.stackadapt.com/templates/23108/csU8SiFgoli-5ilc2aX0Hg/index.html?&click=https%3A%2F%2Fclk.srv.stackadapt.com%2Fclk%3Faid%3D1-2097-176299440907958204102912-4%26cid%3D2681420%26adid%3D11078281%26sid%3D8133a6a5-aba3-4846-8378-179026f00028%26uid%3D54k4_IR5Ste4Nf_KLddJuw%26did%3Dradiopaedia.org%253A%253A159%26adurl%3Dhttps%253A%252F%252Fap.srv.stackadapt.com%26t%3D1762994409%26brandname%3DEyecare%2BPlus%2BOptometrists%26adheading%3D%26iidx%3D0%26nid%3D159%26bip%3DMjAzLjMyLjE0Mi41OQ%26conv%3Dtrue%26curl%3DaHR0cHM6Ly93d3cuZXllY2FyZXBsdXMuY29tLmF1Lz91dG1fc291cmNlPURpc3BsYXkmdXRtX21lZGl1bT1DUEM%253D%26r%3D&fclickout=true" width=300 height=50 marginwidth=0 marginheight=0 hspace=0 vspace=0 frameborder=0 scrolling=no bordercolor="#000000"></iframe></div><div></div><div></div><div><img src="https://www.facebook.com/tr?id=128445976965582&ev=PageView&noscript=1" width="1" height="1"><img src="https://ap.srv.stackadapt.com/cookie?campid=2681420&is_ctv=0&nativeid=11078281&domain=radiopaedia.org%3A%3A159&auctionid=1-2097-176299440907958204102912-4&impindex=0&m=MjAzLjMyLjE0Mi41OQ&isipgen=0&conv=1" width="1" height="1"><img src="https://ap-win.srv.stackadapt.com/win?aid=1-2097-176299440907958204102912-4&sid=8133a6a5-aba3-4846-8378-179026f00028&wp=0.15&rid=7b07614e-e84e-4aa2-9342-d542f167af16&network=159&t=1762994409&said=1-2097-176299440907958204102912-4&sanid=159" width="1" height="1"></div><script src="https://s3.amazonaws.com/stackadapt_public/js/saimp.js" purl="https://ap.srv.stackadapt.com" aid="1-2097-176299440907958204102912-4" iidx="0"></script><script src="https://s3.amazonaws.com/stackadapt_public/js/saurl.js" id="sa-url-script" purl="https://ap.srv.stackadapt.com" aid="1-2097-176299440907958204102912-4" iid="8133a6a5-aba3-4846-8378-179026f00028" br_domain="radiopaedia.org" br_ip="203.32.142.59" network="kargo" br_page_url="https://radiopaedia.org/articles/cerebellum"></script></body></html>