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“ OK LENS ” - NIGHT TIME LENSES FOR DAY TIME FREEDOM

What is orthokeratology ? Orthokeratology ( ortho-k ) involves the use of rigid , gas-permeable contact lenses worn overnight to shape the cornea in order to correct mild to moderate refractive errors , such as myopia and astigmatism . Patients do not need to wear the lenses during the day and can thus be spectacle free . However the effect is temporary and the ortho-k lenses need to be worn regularly at night to maintain clear daytime vision .

Who might benefit from orthokeratology ? Ortho-k has emerged as an appealing option for many kids with myopia , especially those who are involved in sports or other activities that make wearing glasses inconvenient . Parents can insert the contact lenses for their child before he / she sleeps , remove them in the morning and the child will have near perfect vision nearly the whole day provided that the myopia is less than -5.0 D . In addition , some studies have shown that the use of ortho-k lenses may help slow the progression of myopia and parents can consider this option to control their child ’ s myopia .

Why are we worried about myopia ? There has been a dramatic increase in the prevalence of myopia worldwide , especially in the East Asian population where figures of 90 percent have been reported in university populations . Aside from its socioeconomic burden , myopia , even when relatively low , is associated with significantly increased risks of potentially blinding diseases such as myopic maculopathy , retinal detachment , cataracts and glaucoma . Rather than simply treating the consequences , the focus is now on limiting the progression of myopia , which typically peaks between the ages of 8 to 12 years in Singapore .

Does orthokeratology slow down myopia progression ? One of the first studies suggesting that ortho-k might slow down myopia progression was published in 2011 , when researchers from Japan evaluated the effect of ortho-k lenses on eyeball elongation in children , a factor associated with myopia progression . They found that overnight orthokeratology suppressed the elongation of the eyes of children .

Since then , more studies have been published and most of them found that ortho-k has significantly greater efficacy in controlling axial elongation in children compared to spectacle correction . In addition , there appears to be a greater myopia control effect in Chinese children compared to Caucasians , and in those with higher initial myopia .

However , atropine eyedrops have been found consistently to be more effective in controlling myopia progression . A paper published in the American Academy of Ophthalmology Journal used a network meta-analysis to compare 16 forms of intervention . Atropine eyedrops showed clear effects on control of myopia progression , with ortho-k only showing moderate effects . And studies on ortho-k ( unlike the atropine studies ) have not to date included washout data in terms of sustained effect after stopping treatment , which is an im- portant factor to consider .

What are the risks of orthokeratology ? Similar to the use of any form of contact lenses , ortho-k lenses can be associated with complications like cornea abrasions , allergic reactions and severe corneal infections ( known as infectious keratitis ). If not treated promptly , infectious keratitis can lead to perforation of the cornea , and even if treated successfully , can result in a scar , which can affect the vision significantly . These risks can however be mitigated if the use of ortho-k lenses is closely supervised and monitored by eye care professionals .

Conclusions There are many benefits associated with the use of ortho-k lenses , including the control of myopia progression and leading a spectacle-free lifestyle . As ortho-k can be associated with certain eye complications , patient selection and assessment of suitability are very important . Patients on ortho-k must also be monitored regularly by eye care practitioners .

Call 6456 1000 or email Eagle Eye Centre at email @ eagleeyecentre . com . sg to find out more about different modalities to manage and control Myopia in Children .

Eagle Eye Centre www . eagleeyecentre . com . sg

GlobalHealthAsiaPacific . com NOVEMBER 2021

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