What is Myopia Control, and Why is it Important?
Myopia, or short-sightedness, is when the light entering the eye is focussed in front of the retina (rather than on the retina) and creates blurred distance vision. It typically starts between the ages of 7 and 14 and tends to progress throughout the teens and sometimes into the early 20’s and beyond. It is normally corrected with spectacles and/or contact lenses, and some people eventually opt for refractive surgery.
Myopia is becoming more common with each generation. In low degrees it is not too much of a problem, other than the slight inconvenience of having to wear glasses. However in higher degrees (say over -5) spectacles lenses become thicker and heavier, uncorrected vison is more debilitating, and more importantly the risk of certain eye diseases such as glaucoma and retinal detachment becomes higher.
Over the past 3 or 4 years there have been numerous scientific studies which show that certain types of contact lenses can be used to effectively slow down the rate of increase in the myopia in children and teenagers. The progression isn’t stopped, but on average the rate of increase is slowed by around 50%.
If you are interested in the science behind this, here’s a quick overview:
- When contact lenses or spectacles are used to correct myopia, the unfocussed light is correctly focussed on the central part of the eye (the macula) but at the periphery of the retina the light is actually focussed too far back, behind the retina.
- This has been shown to stimulate the eye to grow, in order to make the retina meet that defocussed light. The eye growing is what causes it to become more short-sighted.
- If that peripheral light could be made to focus IN FRONT of the retina, not behind it, this stimulus to grow larger would be removed, thus reducing the rate of worsening of the myopia.
There are two lens types which have been shown to accomplish this:
Orthokeratology, also known as Ortho-K, night-time lenses, and EyeDream lenses, involves the precision fitting of special rigid gas permeable (RGP) lenses which are worn overnight to subtly reshape the cornea. This reshaping effectively corrects the myopia for about a day, so that the following day there is no need to wear glasses or contact lenses. The effect is temporary so the lenses have to be worn every night in order to achieve good vision the next day. The optics the lens produces on the cornea bends the light so that the peripheral defocus is in front of the retina.
Ortho-K works best for those with a maximum prescription of -4.50 and with less than -1.50 of astigmatism. It is a great option for:
- Kids and teenagers with progressing myopia
- Kids, teenagers and adults who would like the freedom for visual correction during the day (even if they aren’t progressing!)
- Those who are unable to wear lenses during the day due to dry eyes or allergies
- People who do a lot of water sports, sailing, swimming etc. where in isn’t practical to wear glasses or soft contact lenses.
For further information on Ortho-K please give us a call or pop in for a chat. You might also like to have a look at http://www.eyedreamlenses.co.uk/.
Soft Multifocal Contact Lenses
These monthly disposable lenses were originally designed for people aged over 45 who need reading glasses. They have both distance and near prescriptions in the lens, and they actually provide the same optics as ortho-k lenses, making them a great option for myopic kids. They are worn during the day rather than at night, which some children may prefer. They are also a great option for young people with prescriptions over -4.50. The efficacy of multifocal lenses for myopia control is around the same as ortho-k, 50%.