What Is Myopia?
Myopia, or nearsightedness, is a vision condition where near objects are clear and everything in the distance is blurry and is the most common ocular disorder worldwide. It happens when light rays focus inaccurately in front of the retina. The axial length of the eye, aka the measurement from the front to the back of the eye, is a good predictor of who will get myopia and how severe it will be.
What Is The Myopia Epidemic?
In 2010, 27% of the world’s population was myopic and 2.8% had high myopia. It is estimated that by 2050, 52% of the world’s population will be myopic and 10% of them will have high myopia.
What Are The Risk Factors?
Genetics definitely play a risk factor: When both parents are myopic, the risk is 1 in 2. When one parent is myopic, the risk is 1 in 3. When neither parent is myopic, the risk is 1 in 4.
There are also lifestyle risk factors, some of which include poor lighting, low levels of outdoor activity and increased near tasks on digital devices.
Why Should We Care?
Most people’s prescriptions will stop changing at around 20-30 years old and because children are becoming myopic at younger ages than ever before, this results in more rapid progression and therefore higher amounts of myopia. When the axial length of the eye increases, it causes the retina to stretch and thin out, and therefore makes it more prone to getting certain eye diseases like cataracts, glaucoma, retinal detachments and myopic degeneration. The strength of myopia is given in 0.25 steps (4 steps = 1 dioptre); each dioptre of myopia results in a 58% increased risk of future eye diseases and 1mm change in axial length can result in as high as 2.00 to 2.50 dioptres of added prescription.
Odds ratios for myopia associated pathologies:
As you can see, the higher the myopia = the higher risk of eye diseases when compared to people with no prescription. Also, when the glasses prescription is changing so rapidly, this causes an increased financial burden on families, especially when the prescription is higher and an additional fee to thin out the lenses is required.
How Do We Slow Down Myopia Progression?
Myopia control refers to slowing down the rate of myopic progression with the use of lifestyle changes, eye drops, specialized glasses and/or contact lenses in children. We recommend starting myopia control before the age of 10 (or at the first sign of myopia) as results become limited after this age. With that being said, we have patients that are still using myopia control options well into their late teens and early 20’s. Some of the ways we can help slow down the rate of progression of myopia include:
Atropine Eye Drops
Atropine in higher amounts has traditionally been used to dilate the pupils and inhibit the eye’s focusing system. The exact mechanism of action is unclear but it is thought that maybe atropine inhibits the sclera from thinning or stretching (and therefore inhibits axial length changes). You still need to wear glasses and/or contact lenses while using Atropine drops and drop compliance is very important. The most common complaint is they do sting a little bit on instillation and it can cause light sensitivity and blurry vision, however most benefit plans will cover the cost of an atropine prescription.
There are multiple lens technologies that slow down myopia progression but we use HOYA’s Miyosmart lens at Kennedy Eye Clinic; it has been shown to also reduce the rate of progression on average by 60%. Normally when light hits the retina in a myopic person, the peripheral rays will focus behind the retina and this causes the eye to elongate and increase axial length. Miyosmart lenses use D.I.M.S. (Defocus Incorportated Multiple Segments) technology to give a 50/50 ratio of light rays that focus on the retina (clear vision) to light rights focusing in front of the retina (blurry vision or myopic defocus); the brain can still see a very clear image because the middle 9.4mm segment of the glasses has zero defocus. Around the center of the lens is a whole bunch of defocused islands in a honeycomb pattern. The technology can only work if the glasses are being worn full time. The cost is $455 for one pair and $730 for two pairs; they include a two year coating warranty as well as a one year prescription change warranty.
3. Soft Contact Lenses
Abiliti contact lenses by Johnson & Johnson are a breathable daily disposable contact lens used in myopia control. It uses a ring defocus technology that delivers great vision and the comfort as their Acuvue 1 Day Oasys lens. These lenses do not correct astigmatism and need to be worn at least 10 hours a day, 5 days a week, to benefit from the technology. The fitting fee is $39 ($100 for new wearers) and the cost per box of 30 lenses is $42 (aka $84 for a 1 month supply).
4. Orthokeratology (Ortho-K) Contact Lenses
Also known as “corneal re-shaping” lenses; these are a special kind of rigid contact lenses that you sleep in, kind of like a retainer for your eyes. They reshape the eyes while you sleep and when you wake up, you remove the lenses and can enjoy clear vision all day without glasses and/or contact lenses. You need to replace these lenses on an annual basis and the results are not permanent. The fitting fee is $925 and the cost per lens is $400.
5. Lifestyle Changes
There is a protective factor in exposure to outdoor lighting so we always recommend children to play outside as much as possible and limit screen time! It is important to note that once myopia has started, being outdoors does not seem to halt it’s progression.
One or more of these options can be combined to slow down the progression of myopia. Please consult with your Optometrist to decide which option(s) is best suitable for your child.
How Do We Monitor Myopia Progression?
Myopia results when the axial length increases outside of age-related norms; when kids are showing rapid changes in myopia, their axial length will change a lot faster than normal. We recommend checking the prescription as well as the axial length at the Kennedy Eye Clinic to make sure the treatment plan chosen is best suited for the patient and intervene early if modifications need to be made.
Enrolling In Our Myopia Control Program
To enroll in our myopia control program, we charge an annual fee of $200 (with a valid SK health card); this includes all follow ups with your Optometrist and at each visit, the doctor will do a prescription check, an axial length measurement (with an associated progression chart) and any treatment modifications or recommendations will also be given.
References: coopervision.co.uk, reviewofmm.com, retinatoday.com