Short-sightedness, or near-sightedness, is a type of refractive error. It’s that type of refractive error that makes you squint as you try to figure out whether that person over there is your wife or someone different entirely. It’s the type of refractive error that makes children sit at the front of the class or end up copying from their friends’ books if they end up in a seat at the back of the room. It’s also the type of refractive error that can cause permanent legal blindness.
What is Myopia?
Myopia is the medical term for short- or near-sightedness. Alongside hyperopia (far- or long-sightedness) and astigmatism, it’s a type of refractive error. Refractive error refers to a mismatch of the eye’s focusing power to the eyeball length. This means that light being focused, or refracted, through the eye doesn’t come to a sharp point on the retina, which is where we need it for clear vision. Instead, in myopia, the focal point falls in front of the retina. This is because the eyeball is essentially too long for its focusing power.
People with myopia will find that their near vision, such as for reading, is not too bad. Conversely, things in the distance will be blurry. Just how far an object needs to go before it becomes blurry will depend on your degree of myopia. If you already wear glasses or contact lenses, you’ll notice that your prescription is typically written with a minus in front of the number, such as -2.50D.
Myopia can be managed with glasses, contact lenses, or laser eye surgery techniques, such as LASIK or PRK. Contact lenses and laser eye surgery do have limitations to the range of treatable prescriptions. For example, many contact lens manufacturers only make lenses up to -12.00D. Your eligibility for laser eye surgery depends on a number of factors in addition to your prescription, such as your corneal thickness.
Not Being Able to See Far into the Distance Isn’t the Only Problem That Comes with Myopia
In fact, myopia is considered so problematic that eyecare experts are calling it a global myopia epidemic. In the year 2020, around 35% of the world’s population had some degree of myopia. However, back in the year 2000, only 23% were myopic. With the current trends we’re seeing around the globe, especially in Southeast Asian countries, by the year 2050, we’re expecting almost 50% of the world to be short-sighted. That’s a lot of people unable to identify people or objects from a distance without their glasses.
So, what’s with all the panic around myopia? Here are some of the potential complications caused by short-sightedness.
- Myopic macular degeneration (MMD). This can cause permanent loss of your central vision, which is received by the macula area of your retina. Because the retina is stretched in an elongated myopic eyeball, tears and bleeds can occur in the delicate tissues around the retina. If you develop abnormal new blood vessels under the retina, known as choroidal neovascularization, you may be treated with eye injections to prevent it from progressing. However, vision that is lost from MMD cannot typically be restored. The higher your degree of myopia, the greater your risk of suffering from MMD.
- Retinal detachment. A retinal detachment is a sight-threatening eye emergency that can happen to anyone. In fact, around 28,000 cases of idiopathic retinal detachments are reported every year in the US. This refers to retinal detachments with no identifiable cause. During a retinal detachment, the retina separates from the underlying tissues of the eyeball. Without being connected to its supporting tissues, the retina is unable to transmit its neural signals to the brain, nor receive the oxygen or nutrition it needs to survive. Similar to MMD, retinal detachments in myopia are more likely because the retina is stretched thin in the elongated eyeball. Again, the risk of a retinal detachment increases the higher the degree of myopia. Treatment for a retinal detachment is with surgery or injection of a silicon gas to push the retina back against the eyeball.
- Cataract. Finally, a complication of myopia that isn’t cause for panic! Cataracts are likely to be something you’ve already heard of, as the vast majority of cataract cases are simply a natural part of aging. However, having short-sightedness can increase your chances of developing an early cataract. This also increases your likelihood of needing cataract surgery, which can be riskier in a myopic eye.
- Open angle glaucoma. Glaucoma is another eye disease that becomes more prevalent with increasing age. However, unlike cataracts, it’s not a normal part of aging. Glaucoma is a disease of the optic nerve, which carries signals to your brain from your eye to interpret into vision. It begins with no symptoms, and the open angle form is entirely painless. As the disease progresses, your peripheral vision begins to deteriorate, eventually leaving you with tunnel vision. In aggressive cases of glaucoma, your central sight may also be affected. Compared to someone with no refractive error, myopia almost doubles your chance of developing glaucoma, and can also be a factor for progression of peripheral vision loss when glaucoma is present.
What Can I Do?
Maintaining regular visits to your optometrist or ophthalmologist is your best chance of identifying and treating any eye diseases early to preserve your vision. Even if you feel your sight hasn’t changed, your glasses are still in mint condition, you could have an asymptomatic retinal hole just sitting there and waiting to turn into a full-blown retinal detachment at the opportune moment.
For children and early teens, there is significant evidence that intervention for myopia is effective. Myopia tends to progress the most rapidly and aggressively in childhood, making this the perfect period to try and delay its advancement. More and more optometrists around the world are beginning to offer what’s known as myopia management or myopia control. These are therapies that have been demonstrated to slow the progression of myopia compared to children with no interventions. Your optometrist may suggest:
- Atropine eyedrops
- Special eyeglass lenses designed for myopia control
- Special contact lenses designed for myopia control
There is also evidence that increased time spent outdoors and less time spent on near work can be protective from developing short-sightedness in children. Plus, we know that under-treating myopia – that is, prescribing a prescription lower than the full degree of the short-sightedness – can actually cause the short-sightedness to progress more rapidly.
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