Nearsightedness: What is Myopia?
Nearsightedness (Myopia) is when close-up objects look clear but distant objects are blurry. For instance, you can read a map clearly but have trouble seeing well enough to drive a car.
Nearsightedness is a common eye focusing disorder. It has been on the rise for several decades. It is estimated that by 2050, nearly half the people in the world will have nearsightedness.
Nearsightedness: Myopia Types
High myopia and low myopia. Mild nearsightedness (generally less than 3 diopters of myopia) is also called low myopia. Moderate nearsightedness or myopia is 3 to 6 diopters of myopia. Severe nearsightedness (more than 6 diopters of myopia) is also called high myopia. Nearsighted children usually become more nearsighted as they age, but their glasses prescription usually stabilizes in their 20s.
Nearsightedness: Myopia Symptoms
Some of the signs and symptoms of myopia include:
- squinting to see properly, and
- difficulty seeing objects far away, such as road signs or a blackboard at school.
Young children with myopia might not complain about their blurry vision, so eye exams and vision tests are important in young children. Some kids are born nearsighted, and some don’t become nearsighted until their teen years.
Nearsightedness: Myopia Causes
For you to see clearly, light rays must travel through the front layers of the eye (the cornea and lens). The cornea and lens work together to bend the light so it lands on the back layer of the eye, called the retina. The retina then sends a signal to your brain that allows you to see.
With nearsightedness, the shape of your eye prevents light from bending properly, so that light is aimed in front of your retina instead of on your retina. For example, the cornea at the front of your eye may be too steeply curved, or your eye may be longer front to back than normal. In either case, the light rays fall short of the retina. When light is not focused on the retina as it should be, your vision is blurry.
Risk factors for nearsightedness.
If a parent is nearsighted, there is a greater chance their child will be as well. But a parent doesn’t need to be nearsighted for their child to be nearsighted. Doctors still don’t completely understand why some people are nearsighted. There are likely many factors involved, and genetics is only one part.
Nearsightedness is often discovered in children when they are between ages 8 and 12 years old. During the teenage years, when the body grows rapidly, myopia may become worse. Between the ages of 20 and 40, there is usually little change.
Too much time spent indoors increases a child’s risk for nearsightedness. Studies show that more time outdoors in natural light reduces a child’s risk.
What Are the Long-Term Risks of Nearsightedness?
Detached retina and nearsightedness. People with nearsightedness have a higher risk for a detached retina. This is when the tissue lining the back of your eye lifts away or separates from the eye wall. It is a serious eye problem that can cause blindness. It is important for people with severe nearsightedness to visit an ophthalmologist regularly for exams to check the retina. The more severe your nearsightedness the greater your risk. Ask your ophthalmologist to discuss the warning signs of retinal detachment with you.
People with severe nearsightedness also have a higher risk of developing glaucoma, cataracts and other eye diseases.
Nearsightedness: Myopia Diagnosis
An eye doctor diagnoses nearsightedness as part of a comprehensive eye examination.
In patients old enough to read the letters on an eye chart, your ophthalmologist can use a machine called a phoropter to measure your glasses prescription and diagnose nearsightedness.
In a patient too young to read the letters on an eye chart, your ophthalmologist can use a device called a retinoscope to measure where light is being aimed inside the eye. This allows an ophthalmologist to measure a young child’s glasses prescription.
Nearsightedness: Myopia Treatment
Eyeglasses and contact lenses. Eyeglasses or contact lenses are easy, common ways to correct nearsightedness. They help to focus light on the retina in the back of your eye so that you can see more clearly. Over time, you will need new prescriptions as your eyes change.
There are many options to consider when buying glasses or contacts. Talk with your ophthalmologist about the lens choices that best suit your vision and lifestyle needs.
Refractive surgery: In adults with nearsightedness, sometimes the nearsightedness can be fixed with refractive surgery. The two main types of refractive surgery are refractive laser surgery and refractive lens exchange. In refractive laser surgery, a laser reshapes the cornea to adjust how light travels through it. Here are some of the more common procedures:
In refractive lens exchange, an ophthalmologist removes the natural lens inside your eye and replaces it with an artificial lens. The new artificial lens helps to aim light at the retina in the back of the eye so you can see more clearly.
As with any surgery, refractive surgery carries risks of complications and side effects. For instance, after having a refractive procedure, you may see glare or rings (halos) around lights. You might also have poor night vision.
Talk with your ophthalmologist about your vision needs and expectations. Together you can explore your options for achieving better vision.
Nearsightedness: Myopia Prevention
Can I Prevent or Slow the Progression of Nearsightedness?
A great first step to prevent or slow the progression of nearsightedness is to encourage your child to spend more time outdoors. Balancing indoor time with outdoor time is beneficial for a child’s health and well-being. Outdoor time is protective against nearsightedness and a good prescription for eye health.
There is no scientific evidence to suggest that eye exercises, vitamins or pills can prevent or cure myopia.