Nearsightedness vs. Farsightedness: What Are the Differences?
If you are nearsighted or farsighted, you can see clearly at some distances but not at others. However, these two conditions are very different. If you have either, you will want to visit an ophthalmologist or optometrist to correct your vision so that it is sharp at all distances.
This article will discuss what sets nearsightedness and farsightedness apart. Learn here about the symptoms related to each, the causes of both, what diagnosing them involves, what options are available for treating them, and what measures you can take to prevent them.
Koron / Getty Images
Symptoms
With either nearsightedness or farsightedness, you recognize that something is off with your vision. Something you could easily make out before from a certain distance is becoming more challenging to see.
The symptoms of nearsightedness (myopia) and farsightedness (hyperopia) differ in terms of the distances at which you have trouble seeing objects. If you are nearsighted, you may see well up close but poorly at a distance. If you are farsighted, your vision may be sharp or blurry at a distance but poor up close.
Check out how nearsightedness and farsightedness stack up:
Nearsightedness
Difficulty seeing from a distance
Squinting to try to read distant letters or see faraway objects more clearly
When viewing something at a distance for too long, eye strain and fatigue set in
Farsightedness
Difficulty seeing up close
Squinting to focus on objects up close
When viewing something up close for too long, eye strain and fatigue occur
With both of these conditions, difficulty seeing can strain the eyes and make them feel sore. You may also squint in an attempt to see more clearly. The critical difference that can help you tell these apart is the distance at which you experience blurry vision.
Causes
Both nearsightedness and farsightedness depend on the shape of the eye and how you see. Ideally, light travels through the front part of the eye, and the rays converge on the light-sensitive retina at the back of the eye. The retina then conveys this information to the brain via the optic nerve.
Nearsightedness
But if you are nearsighted, the light rays don't converge on the retina. Instead, they land in front of it.
This may result from having a cornea (the clear tissue at the front of the eye) that curves more than usual and bends light rays too much. Or, your eye may have an unusually long front-to-back length. Because of this, the light rays converge in front of the retina instead of onto it.
Nearsightedness tends to run in families. But genetics is not the only factor here. You can still have nearsighted vision even if it doesn't affect any of your family members. However, the other possible causes of it aren't always clear.
Farsightedness
If you are farsighted, you may have an unusually flat cornea. Or, your eye is shorter than usual. Either of these can cause the light rays to land behind the retina instead of focusing directly on it. If this is mild enough, you may not notice any issues.
In many cases, this may mean that you cannot see objects up close clearly, even if you can view things at a distance well. If your farsightedness is severe, objects may appear blurry not just up close but at any distance.
Farsightedness also tends to run in families while still precluding any need to have a close family member with the condition for it to affect you. Researchers have also been unable to pinpoint the other possible reasons that farsightedness occurs.
Diagnosis
An ophthalmologist or optometrist can diagnose nearsightedness or farsightedness during a routine comprehensive eye exam. They will ask you to read letters from a chart as part of the exam.
To get the right prescription to correct the refractive error, the ophthalmologist may use a phoropter to test your vision. You look through this instrument through different lenses to determine the best correction.
The ophthalmologist will use a retinoscope for children who cannot yet read to determine if the child is nearsighted or farsighted. This instrument shines a light into the eye and detects the reflection off of the retina.
Treatment
The ophthalmologist or optometrist needs to distinguish nearsightedness from farsightedness. The prescription they use to treat your vision can differ widely for each, and the wrong one will only make your vision blurrier.
Nearsightedness
The eye doctor will often prescribe glasses or contact lenses to sharpen your distance vision if you are nearsighted. Contact lenses or spectacles focus the light onto the retina where it would ideally land.
For adults who would rather not wear glasses or lenses, the ophthalmologist may correct the vision surgically, flattening the cornea. The following surgical approaches may offer further options for you:
Laser-assisted in situ keratomileusis (LASIK): With this approach, the ophthalmologist cuts a corneal flap and then uses an excimer laser to reshape the tissue underneath so that it is flatter. Then the flap of corneal tissue returns to its original position and heals in place with a flatter shape.
Photorefractive keratectomy (PRK): Using PRK for nearsightedness, the ophthalmologist flattens the corneal surface with an excimer laser.
Refractive lens exchange (RLE): With this type of correction, the ophthalmologist removes the natural lens inside your eye that focuses light on the retina and replaces it with an artificial one that can correct steeper curvature or extra length.
Radial keratotomy (RK): In cases of mild nearsightedness, the ophthalmologist can make small cuts in the cornea to help flatten this and ensure that the light rays reach the retina.
Small incision lenticule extraction (SMILE): This relatively new technique uses a laser to sculpt out a piece of tissue below the cornea surface to flatten it and help ensure the light rays land on the retina.
Farsightedness
If you are farsighted, your ophthalmologist will usually begin by offering a prescription for glasses or contact lenses. Such lenses bend the light to refocus it on the retina, compensating for a cornea that's too flat or an eye that's too short.
For those who would rather not wear glasses, there are some surgical solutions, such as the following:
Refractive laser surgery such as LASIK or PRK: These procedures can steepen the cornea and ensure that the light rays land on the retina. This approach can only work if your farsightedness is relatively mild.
Refractive lens exchange: With this approach, the ophthalmologist will remove the natural lens and put in an artificial one that can compensate for the hyperopia.
If your child is farsighted, they may outgrow it in some cases. But you must consult an eye doctor to see if this is true in your child's case. Otherwise, untreated farsightedness can lead to lazy eye (amblyopia), which can result in further vision loss.
Prevention
Ideally, a person wouldn't develop nearsightedness nor farsightedness in the first place. Unfortunately, there is no silver bullet in either case, but some options may have an impact in some cases.
Nearsightedness
It is possible with myopia to potentially slow the progression of this refractive error while the eye is still developing. Here are some approaches to consider:
Low-dose atropine drops: A mild dose given to those ages 5–18 for two to three years can slow down myopia progression. Scientists are still determining why this may work, although they think it may have something to do with keeping the eye from growing too long.
Contact lenses with peripheral defocus: With these lenses, the vision in the middle is corrected so that distance vision is sharp, but the vision off to the side is blurry. Researchers think that this may slow eye growth, particularly for those with close relatives who are nearsighted.
Orthokeratology (ortho-k): For this approach, your child wears a contact lens that flattens the eye while they sleep overnight. When they wake up, the cornea is briefly flatter, and images are sharper. Though this effect is temporary, it may still permanently reduce some myopia.
Play outdoors: There's also some thinking that exposure to sunlight can help keep the eye from elongating and keep myopia in check. Scientists are unsure why lack of sunlight appears to be an environmental trigger for nearsightedness.
Farsightedness
Unfortunately, there is currently no way to prevent farsightedness. You cannot use vitamins, eye exercises, or medicine to avoid this.
Summary
Nearsightedness and farsightedness have both similarities and differences. In both cases, you must deal with some blurriness in vision unless you get it corrected. The critical difference between the two is just where the blurriness occurs.
The causes here mirror each other. In nearsightedness, the cornea is either too steep or the eye is too long. In farsightedness, the cornea is either too flat or the eye is too short. Though basic treatment here revolves around glasses and contact lenses, nearsighted people may have more surgical options than their farsighted counterparts.
