Myopia in Children and Teenagers
Myopia, also known as shortsightedness or nearsightedness, is a condition in which the eye is longer than average length and images that pass through the pupil do not meet with the back of the eye, the retina, which in turn causes blurred far vision.
Myopia commonly develops in school aged children. Progression of myopia is more aggressive between the ages of 6 to 13 years old however can continue to progress into ages 20’s or 30’s.
Myopia Risk Factors
The frequency of myopia is increasing worldwide; currently there is extensive ongoing research into the causes of myopia and its progression. Myopia is genetically linked however exactly how is unknown. It is estimated that if one parent is myopic the risk is 60-90% higher in the child.
There is continuing research and ever changing theories as to exactly why myopia may progress. There is some evidence that as well as genetics, some lifestyle factors contribute to the progression of myopia. The current research has found that it is not just the increase of near tasks or digital devices but that children are spending less time outdoors.
Research shows that the more myopic a person becomes the more at risk they are for serious eye health conditions later in life. Some of these conditions are retinal detachments, cataracts, macular degeneration and glaucoma. Current research has found that there is no level of myopia that can be considered “safe” in comparison to those who aren’t myopic.
Hence, the best practice in addition to correcting vision is to also consider treatments proven to reduce the rate of myopia progression and at an earliest age possible. Another consideration is quality of life; if your child is myopic the higher the prescription = the more reliance on vision correction, which may impact lifestyle choices like sports.
Prior to commencing any intervention to slow myopia progression a range of tests are needed to assess treatment options then also to monitor the effectiveness of the treatment. Most of the research uses axial or eye length and the prescription measurements to monitor treatment efficacy.
Management options for slowing the progression of Myopia
Ortho K is a well established treatment program for vision correction to enjoy the freedom from spectacles or contacts lenses throughout the day. The custom-designed hard contact lenses are to be worn whilst sleeping then upon removal in the morning, it results in an immediate improvement of vision. The lenses work by gently reshaping the front structure of the eye, the cornea. Initial wear of these lenses may take some time to adjust but comfort and vision improves within a few days, worn consistently they can be an effective treatment for many years.
Studies have shown the effectiveness of Ortho K as strong when used in reducing the progression of myopia, making it one of the leading interventions. Click here for more information about Ortho K.
Multifocal soft contact lenses (MFSCLs) are contact lenses which correct vision whilst changing the pathway of peripheral light rays in the eye. These contact lenses come in daily or monthly disposable modalities but cannot be slept in overnight, they are both just for daytime wear and vision correction.
They have been shown to have a strong to moderate effectiveness in reducing the rate of myopia progression.
Atropine is an eye drop which is mainly used in the diagnosis of eye conditions or eye therapy. Research shows Atropine in any dose slows the progression of myopia, however the mechanism how is unknown. In its full dosage, 0.5 or 1%, it causes a strong but reversible dilation of the pupils and temporarily halts the eyes focusing system. In low doses (0.05%) studies have shown the side effects are minimal. Additionally, as it is to be instilled at night any side effects are likely to have worn off by the morning with this dosage.
Despite strong research showing its strong to moderate efficacy in reducing myopia progression it is not yet approved by the Australian Therapeutic Goods Administration (TGA) for this purpose and hence the use of this scheduled medication is off label. Again, because use is off label it is not available commercially and a compounding pharmacy must make it fresh every month.
Bifocals are spectacle lenses which have a line separating the distance prescription to the near prescription and Multifocal lenses or PALs are spectacle lenses which seamlessly (without a line) progress from a distance prescription at the top to a near prescription at the bottom. The research behind having a prescription for near which is different to distance, such as in these lens options, is that it would provide clear vision over a range of viewing distances which changes the focus of light inside the eye.
Several studies show moderate to weak effectiveness in slowing progression of myopia when wearing bifocals, multifocals or PALs compared to single vision spectacles. These options work better in children with low myopia and additional focussing disorders.
These spectacle lenses have been designed to change the path of light entering the eye to slow the progression of myopia by inducing peripheral myopic defocus. One family of lens brands is MyoVision and MyoKids by Zeiss. The current literature shows this spectacle lens has the best efficacy for east and Southeast Asian children aged between 6 and 12 years of age with a family history of Myopia. Myovision has been shown to have a moderate to weak reduction in myopia progression.
The main drawback of this lens, besides lower efficacy than other options, is that the eyes may not always be centred behind the lens or children may look over the top or under these lenses (as with any spectacle modality of management) as opposed to in contact lenses where the lens moves with the eye.
New research shows increased outdoor time is a protective factor for myopia progression. Alongside myopia management options it should be encouraged for children or teenagers with progressing myopia to spend more than 90 minutes outside a day with appropriate UV or sunglasses eye protection.
Additionally a good habit to get into whilst indoors is to take frequent breaks while doing close work, every 20 minutes time should be taken to focus far away and allow the eyes to relax. Near tasks or near screen time outside of school should be limited to no more than 2 hours a day.