Myopia or nearsightedness is reaching epidemic proportions. In a single generation the incidence of myopia has doubled. What is more startling is that researchers predict the incidence will increase an additional 40% over today’s numbers by the year 2050. Although genetics play a role in myopia development, studies are showing more evidence of behavioral and environmental factors contributing to the increase. The most prominent of them being less outdoor play during a child’s developmental years and more screen time both at play and at school.
While there is no outright cure for myopia, there are now options available to treat it. Instead of giving our children thicker glasses or stronger contacts every year, we are able to slow down or even halt its progression ensuring better vision for life. At the same time, we can reduce their risk for serious eye diseases associated with high myopia such as retinal detachments, early cataracts, and glaucoma. The chart below details these health risks associated with myopic progression.1
1. Flitcroft, D. I. (2012). The complex interactions of retinal, optical and environmental factors in myopia aetiology. Progress in retinal and eye research, 31(6), 622-660.
There are three treatment options currently available which have proven through research to be most effective in myopia control. These are: compounded atropine eyedrops; orthokeratology; and specialized daily soft contact lenses. While the efficacy of each method has proven to be essentially equal, a particular method may be chosen do to the fact it fits best into lifestyle for the child. Methods can be combined if a child still shows myopia progression on a single method.
Atropine drops have been used for many years especially in other countries to slow myopia progression. Atropine works on relaxing the accommodative or focusing mechanism of the eye. There is belief that progression occurs due to “focusing fatigue” from all the sustained near work children are doing. The problem with commercially available full-strength atropine is that it has the undesirable side effects of pupil dilation, as well as too much relaxation of the eye’s ability to focus. These side effects leave children light sensitive along with having difficulties reading without bifocals or reading glasses. This has led researchers to study diluted or compounded atropine. Multiple clinical studies have shown Atropine 0.01% to be as effective in controlling progression as full-strength atropine without giving children the negative side effects. Atropine is relatively easy to adapt into a child’s lifestyle. Typical dosing is one drop in the eyes once per day.
Orthokeratology or ortho-k is a method where a variation of a gas permeable contact is placed on the eye before sleeping. It harnesses the tear film to apply a gentle pressure causing a measured amount of flattening to the central cornea. This flattening allows the image to be aligned on the retina providing clear vision in much the same way LASIK does. This allows the patient to see clearly during the day without glasses or contacts. The difference between ortho-k and other treatments is that the effect is reversible. The effect must be maintained by continued nightly wear of the lenses, much like a retainer for the eyes. Once the patient stops wearing the molds, the eye returns to its pretreatment level within a few days or weeks depending on how long the lenses have been worn. The technique has been around for decades, but improvements in lens design and material, as well as its ability to control myopic progression, have caused in rise in usage. It still remains a specialty practice however, due to the time and skill level required to properly fit the lenses.
Control of myopic progression through ortho-k is achieved through a process known as “myopic defocus” as illustrated in the diagram below.
In the myopic eye, traditional spectacle or contact lens correction pushes the image back to the central retina to allow us to see. However, it does so in a single focal plane. Due to the fact that the eye is curved causes the peripheral light rays to be focused behind the retina. This leads to an area of hyperopic defocus as illustrated by the blue line. The theory is this area of hyperopic defocus acts as a stimulus for the eye to grow longer, causing it to become more myopic due to the fact that the eye wants to “catch up” to that peripheral image. With ortho-k, the central cornea is flattened to allow vison correction resulting in a slight steepening of the mid-peripheral cornea. This results in the peripheral light rays being refracted to land in front of the retina causing an area of myopic defocus as illustrated by the red lines in the diagram above.
Research has shown that while hyperopic defocus of the peripheral retina acts as a stimulus for progression of prescription, myopic defocus of the peripheral retina does the opposite. It acts to slow down or even halt progression since the eye no longer needs to “catch up” to that peripheral image.
Ortho k does have some advantages over the other methods. The biggest advantage of ortho-k is that after a few nights of lens wear, the child achieves full time vision correction, much like LASIK. This is due to the fact that the child is able to see clearly with the lenses on as well as off. The lenses only need to be worn at night allowing the child freedom from any type of vision correction during the daytime. This can be especially helpful for swimmers or other athletes, as they do not have to worry about losing a contact or breaking their glasses. Also, the ortho-k lenses are smaller than regular soft contacts, making them easier for children to handle, insert, and remove. Lastly because of the consistency of ortho-k, the area of myopic defocus of the peripheral retina is maintained around the clock, contributing to myopia control.
However, this is the most time-consuming method on the side of the doctor and patient in the beginning. Each ortho-k lens is custom designed for the eye and requires multiple follow up visits initially to ensure it is molding the eye appropriately. Due to the work involved with this process, it is also initially the most expensive of the methods. Lastly for the process to be effective, the lenses need to be worn during a normal sleep cycle, ideally for 8 or more hours per night. This can be difficult for some patients, especially during the teenage years.
There are soft contact lens options that have come onto the market that optically mimics what ortho-k does as far as creating myopic defocus of the peripheral retina. For this reason, it is thought to control the progression of myopia in this same manner. Most children notice no difference in vision when wearing this lens as compared to a normal contact lens.
Due to the fact this is a soft disposable daily lens very little maintenance required. The child wears the lens for the day and throws them away at the end of the day. No cleaning is required. On most occasions, these lenses are immediately very comfortable on the eye.
Just like any other contact lens the child will still require glasses for when they are not wearing their contacts. This differs from ortho-k where the child maintains constant vision with nightly wear of their molds. Also, the myopic control or myopic defocus will only occur when wearing the lenses.
All three methods of myopia control have their advantages and disadvantages. There is no correct or incorrect choice, it just depends on what you feel would best fit your lifestyle and the lifestyle of your child. The important thing is, whichever choice you make, you are doing something to help stop their eyes from getting worse.
Despite mounting research to support its efficacy, all methods of myopia control are currently considered “off label”. For this reason, insurance companies do not cover the cost of the programs. Insurance allowances can be used towards the cost of materials for ortho-k and the NaturalVue lenses, but not toward the program fees.
If you have any specific questions about myopia control please feel free to email the doctors directly.
Dr. Jenna Lewis: email@example.com
Dr. Ronald Jurcak: firstname.lastname@example.org