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Myopia Control

Myopia – ‘shortsightedness’ or ’nearsightedness’ is where the distance vision is worse than the near. Normally, light is focused to the level of the retina, in myopia, the light is instead focused to a point in front of the retina. As myopia increases, there is physical growth of the eye where the length of the eye increases (this is termed axial length elongation). The point of focus goes further away from the retina as the eye grows.

Myopia is on the rise. A study shows myopia prevalence in children in the UK has more than doubled in the last 50 years6. More than 50% of the global population will develop myopia by 20504. In the past, low levels of myopia were deemed the norm, just like normal levels of hypermetropia (longsightedness) and astigmatism where it poses little or no risk to eye health. The lower degrees of myopia were described as ‘physiological myopia’. It has long been known that higher levels of myopia (typically higher than -5.00DS) poses greater risk of developing other eye conditions, including sight threatening ones. This is classed as ‘pathological myopia’.

A paper published by an Ophthalmologist2 in 2012 changed our view of myopia. What we now believe is that there is no level of myopia that can be described as ‘physiological’. This is to say that even low levels of myopia increase the risk of certain ocular conditions. The statistics show someone with just -1.00DS myopia has double the risk of developing glaucoma, cataract, retinal detachment and myopic maculopathy. From -3.00DS to -5.00DS there is tripled risk of glaucoma and cataracts and 9 times the risk of retinal detachment and myopic maculopathy. Bearing in mind that this range was previously thought to be within the ‘physiological myopia’ bracket. Above -5.00DS, the risk of retinal detachment goes up to 20 times and for myopic maculopathy goes up to an alarming 40 times risk. Myopic maculopathy is 1 of the top 5 causes of blindness among working age people in the United Kingdom1.

The strong evidence provided by research tells us that myopia at any degree increases the risk of eye disease. The greater the degree of myopia, the greater the risk of sight threatening eye disease. We now need to be very serious in actively reducing the progression of myopia from as early as possible.

 

Myopia control

Glasses are prescribed for myopia to correct vision however they do not prevent progression. There are various methods to help slow the progression of myopia, these include:

Bifocals or progressive addition spectacle lenses– These are lenses similar to glasses used in adults for presbyopia, a near addition is provided to reduce the amount of accommodation needed for close work. Use of this type of correction in myopic children can help to reduce the rate of myopia progression.

Soft multifocal contact lenses– These contact lenses are intended for use for adults with presbyopia but their use in children and teenagers with myopia has shown to reduce the rate of myopia progression.

Orthokeratology with rigid gas permeable lenses. These are overnight wear lenses that mould the central corneal shape to provide corrected vision throughout the day. The effect of the corneal re-shaping causes a peripheral defocus in the peripheral retina. This method has shown to be effective in slowing the myopic growth of the eye3.  For more information, please see the Orthokeratology page.

Pharmacological – daily use of low dose atropine drops have proven to be an effective method for myopia control. This form of the drug is neither available nor licensed for use in Europe.

MiSight® lenses– These are specialized soft contact lenses produced by CooperVision® specifically designed for myopia control. Currently, this lens type is the only one to be licensed for myopia control treatment. It has just become available to a select number of practices in the United Kingdom and we are one of them.

An initial study by CooperVision® has already shown really positive effects. The study consisted of a 3 year trial of 144 myopic children, half wearing the MiSight® lens and the other half wearing a normal daily soft lens. Results showed that with the MiSight® group, there was a 59% reduction in myopia progression. This is very encouraging stats which works equally well if not better than Orthokeratology.

How do they work?

They are daily disposable lenses with ‘ActivControl’ myopia management technology. There are 2 treatment zones within the lens to defocus part of the image in front of the retina rather than behind. This effect helps to slow the growth of the eye. Unlike other lenses, the amount of defocus is the same at all the prescription powers available.

 

Which is the best option for my child?   

The 2 most effective treatment options available are Orthokeratology and MiSight® lenses. There are limitations in both options so the choice very much depends on your child’s prescription. Orthokeratology is most effective for myopia of up to around -5.50DS. MiSight® lenses can be used in much higher levels of myopia but best suited only for low levels of astigmatism. We also need to consider the child’s ability to wear and handle certain lenses. Lifestyle choices such as sporting activity also plays a big role when deciding which to go for. If the prescription falls outside the range for both these options, then we would then consider the other choices or a combination of options. Ultimately, an initial assessment by one of our Optometrists will be required to make the decision and this may include the use of drops to dilate the pupils for further assessment.

Preventing the onset of myopia

Research shows that the prevalence of myopia is lower in children who spend more time outdoors5,7. More encouragement of outdoor activities is recommended especially for children with a strong family history of myopia.

 

 

References:

  1. Evans JR, Fletcher AE, Wormald RPL, et al. Prevalence of visual impairment in people aged 75 years and older in Britain: results from the MRC trial of assessment and management of older people in the community. Br J Ophthalmol 2002;86:795–800.
  2. Flitcroft DI. The complex interactions of retinal, optical and environmental factors in myopia aetiology. Prog Retin Eye Res. 2012;31:622-60
  3. Hiraoka T, Kakita T, Okamoto F, Takahashi H and Oshika T. Long-Term Effect of Overnight Orthokeratology on Axial Length Elongation in Childhood Myopia: A 5-Year FollowUp Study. Invest Ophthalmol Vis Sci. 2012 Jun 22;53(7):3913-9. doi: 10.1167/iovs.11-8453.
  4. Holden BA, Fricke TR, Wilson DA, Jong M, Naidoo KS, Sankaridurg P, Wong TY, Naduvilath TJ, Resnikoff S. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology. 2016 May;123(5):1036-42. doi: 10.1016/j.ophtha.2016.01.006. Epub 2016 Feb 11.
  5. Rose KA, Morgan IG, Smith W, Burlutsky G, Mitchell P, Saw SM. (2008) Myopia, lifestyle, and schooling in students of Chinese ethnicity in Singapore and Sydney. Arch Ophthalmol. 2008 Apr;126(4):527-30
  6. Sara J. McCullough, Lisa O’Donoghue, and Kathryn J. Saunders. Six Year Refractive Change among White Children and Young Adults: Evidence for Significant Increase in Myopia among White UK Children. PLoS One. 2016; 11(1): e0146332.
  7. Sherwin JC1, Reacher MH, Keogh RH, Khawaja AP, Mackey DA, Foster PJ. The association between time spent outdoors and myopia in children and adolescents: a systematic review and meta-analysis. Ophthalmology. 2012 Oct;119(10):2141-51. doi: 10.1016/j.ophtha.2012.04.020. Epub 2012 Jul 17.