Myopia (nearsightedness) and hyperopia (farsightedness) are two main types of refractive errors. These errors occur due to eye abnormalities that prevent light from focusing on the retina. The retina, which contains light-sensitive cells at the back of the eye, communicates signals to the brain to interpret what you see. This blog will explain the main difference between myopia and hyperopia and how the treatments vary.
Myopia vs. Hyperopia
The cornea (the outer protective layer of the eye), the lens (the clear, curved structure at the front of the eye), and the retina (the thin, light-sensitive layer of tissue at the back of the eye) all work together to produce vision.
In people without vision problems, the cornea and lens help bend light rays so that the focal point lands on the retina. The retina then conveys this information to the brain via the optic nerve, which results in a clear image. In people with myopia or hyperopia, vision problems occur because the focal point does not land properly on the retina properly resulting in an incomplete, blurry image.
Refractive errors, such as myopia and hyperopia, stem from the following issues:
- Aging of the lens (too thick)
- Cornea shape (too curved or too flat)
- Eyeball length (too short or too long)
The main difference between the two is where the point of focus occurs – with myopia, it occurs in front of the retina; with hyperopia, it occurs behind your retina. The words nearsightedness and farsightedness can be confusing for some, as people tend to think nearsightedness means you can’t see up close (hence “near”) and farsightedness means you can’t see from a distance (hence “far”).
However, nearsightedness simply means the focus is at the front of the eye, which makes your vision normal at close range, or near, but blurry at a distance. Likewise, farsightedness means the focus is farther away, which makes your vision blurry up close.
Myopia
Myopia comes from the Greek word myopia, which translates to “close to the eyes.” This condition occurs when the point of focus is in the front of the retina, making near objects appear clear, but objects farther away appear blurry.
In most cases, an elongated eyeball is the cause of myopia – the longer the eyeball, the more difficult it becomes for the focal point to reach the retina. A cornea that is too curved or a lens that is too thick can also cause myopia.
Myopia is one of the most common eye conditions that affects millions of people. In fact, the American Academy of Ophthalmology estimates nearly half the world’s population is nearsighted.
Myopia falls under two categories: low myopia and high myopia. Low myopia is less than 3 diopters (the unit used to measure the optical power of a lens), while high myopia is more than 6 diopters. High myopia is a severe condition that can lead to retinal detachment.
Many people develop myopia as children, usually between the ages of 8 and 12 years old, and their vision worsens into early adulthood (20s) before eventually stabilizing.
It is unclear why some people are more at risk of developing myopia. Genetics plays a role, as do some environmental factors. Some research suggests children who spend more time indoors are more likely to have nearsightedness.
Hyperopia
Hyperopia is the opposite of myopia, in which objects can be seen clearly at a distance, but they are blurry up close. In many cases, the eyeball is too short, causing the focal point of light rays to land behind the retina. Hyperopia also occurs if the cornea is too flat or if the lens is too thick.
While most people with farsightedness can see images at a distance, this is not the case for everyone. For example, severe hyperopia can affect how you see images both up close and at a distance.
Hyperopia is not as common as myopia – only about 5 to 10 percent of people are farsighted, according to the National Eye Institute.
The inability to see images clearly up close is generally thought of as a vision problem for older adults. While this is partially true – most people over the age of 65 have some degree of farsightedness – farsightedness is also common in children. However, children with this condition do not have blurry vision because their lens is flexible enough to produce a clear image. As children grow into adulthood, the eye is more elongated, thus reducing farsightedness.
Like nearsightedness, genetics play a role in farsightedness, as it tends to be familial.
What Happens if You Have Myopia or Hyperopia?
Changes to your vision are gradual, so it may be difficult to pinpoint myopia or hyperopia. The following list of symptoms can help prompt a visit to an eye care provider:
Myopia Symptoms
- Objects at a distance appear blurry
- Headaches
- Eye strain
- Squinting to see images at a distance
- Tired or heavy eyes when constantly looking at a distance, such as when driving
Hyperopia Symptoms
- Objects up close appear blurry
- Eye strain
- Headaches when looking at images up close
- Squinting to see images up close
How do Doctors Treat Nearsighted and Farsighted Patients?
There are several options to treating vision issues, ranging from contacts and eyeglasses to laser surgery and lens replacement.
Glasses
Eyeglasses are one of the easiest ways to treat nearsightedness or farsightedness. In either case, glasses help focus light on the retina (instead of in front or behind) to help you see clearly.
The type of lens is the main difference between glasses for myopia and glasses for hyperopia. People who are nearsighted require concave lenses that are thicker on the sides and thinner in the middle. The shape helps diverge (spread out) light rays. People who are farsighted require convex lenses that are thinner on the sides and thicker in the middle. The shape helps light rays focus on the retina. Many people with hyperopia opt for reading glasses because they do not need corrective lenses all the time.
Contacts
Similar to eyeglasses, contacts help focus light on the retina. The only difference is contacts are worn directly on your eye. Your eye doctor will prescribe concave contact lenses for nearsightedness and convex lenses for farsightedness.
Refractive Laser Surgery
Although eyeglasses and contacts help focus light on the retina, they do not permanently fix your vision. For a permanent treatment option, either LASIK or photorefractive keratectomy (PRK) can change the shape of your cornea so you can see clearly. To correct myopia, the cornea is flattened. Conversely, laser surgery for hyperopia involves steepening the cornea to make it more curved.
The main difference between LASIK and PRK is the surgical approach. With LASIK, the surgeon makes a thin flap in the outer cornea to access the inner cornea and change its shape using a laser. The flap is then replaced. With PRK, the outer surface of the cornea, called the epithelium, is removed to access the inner cornea. The epithelium regrows several days after surgery.
Refractive Lens Exchange
This type of procedure (also called clear lens exchange or refractive lensectomy) is for people with refractive errors who are not candidates for laser surgery. A refractive lens exchange removes the lens and replaces it with an artificial intraocular lens (IOL). The implantation of an IOL is beneficial for people with high myopia or whose cornea is too thin for LASIK.
In another type of procedure, phakic intraocular lenses (PIOL) can be placed inside the eye without removing the existing lens. PIOLs are beneficial in treating myopia.
Treating Refractive Errors at DMEI
Refractive errors such as myopia and hyperopia can make it difficult to carry out everyday tasks such as driving or reading a menu at your favorite restaurant. If you notice any changes to your vision, contact an eye doctor to schedule an eye exam and explore possible treatment options to see clearly.
For more information on myopia and hyperopia, our experienced team of optometrists and ophthalmologists are here for you. Request an appointment today to receive a personalized treatment plan.
