What’s the Difference Between Farsighted and Nearsighted?Nearsighted vs farsighted.
This is another area where many people are confused. When I was a child, all I learned was that farsightedness meant that you could see far and nearsightedness meant that you could see near. That is about as far as most people go with their understanding of these two different eye conditions. In this blog post, I will describe the difference between farsightedness and nearsightedness, and what nearsighted versus farsighted lenses look like so that you can tell immediately if someone is far sighted or near sighted. To the best of my ability, I will describe what causes farsightedness and nearsightedness.
Nearsighted versus farsighted lenses.
- The lenses are thicker in the middle and thinner at the edges
- A farsighted lens magnifies objects. The higher the power of the lens, the more magnification you will see. This also applies to people’s eyes: when you look at someone who has strongly farsighted lenses on their eyes, their eyes will appear larger.
- The notation for a farsighted lens is “plus“. This means that the eyes of the person who is wearing them needs more focusing which is why it has a +. In order to focus clearly you need to “add“ focusing power to the eye to allow the person to see clearly.
- Farsightedness is also called hyperopia
- The lenses are thinner in the middle and thicker at the edges.
- Nearsighted lenses will make someone’s eyes look smaller.
- Nearsighted lenses act as a “minifying“ lens versus magnifying lenses that make images appear larger, nearsighted lenses make images appear smaller.
- Nearsighted lenses have a negative sign in front of them indicating that they subtract focusing power from the eye to allow people to see more clearly.
- Nearsightedness is also called myopia.
What is the difference between nearsighted vs farsighted?
The basic difference between nearsightedness and farsightedness is that farsighted eyes need additional focusing power to see clearly and nearsighted eyes need less focusing power to see clearly. Either refractive error can be corrected with glasses or contact lenses, but an awesome treatment over the past 25 years has been Lasik, PRK, SMILE, Refractive lens exchange, and cataract surgery. All of these can allow a modification of the focusing power of the eye from either a laser changing the shape of your cornea or an artificial lens going inside your eye to correct the refractive error. I think of the Hubble space telescope that went up but was not focused properly so NASA had to send a $250 million camera to fix it and now the Hubble space telescope of “sees“ perfectly clearly and gives us amazing images that provide knowledge of our universe.
Nearsighted vs farsighted people both have difficulty seeing clearly, but due to the difference in the refractive error, they have difficulties in different ways.
For farsighted patients, I always felt bad because children with extreme farsightedness have a difficult time reading because their focusing muscles can’t work enough to allow them to see clearly. This can lead to a lazy eye (amblyopia), crossed eyes (strabismus), loss of stereoscopic vision (depth perception), and can be a permanent handicap if not corrected early in a child’s life. It often goes undetected especially when there is a combination of farsightedness and astigmatism. The child will function normally, but may not be able to see images clearly. This also can lead to amblyopia, or lazy eye which cannot be fixed later in life. Typically after age 7 it becomes nearly impossible to improve a child’s best corrected vision if the amblyopia has not been caught early. For milder farsightedness, it also can be difficult to read because focusing muscles have to work harder than they otherwise would. However, a small degree of farsightedness (recalled this latent hyperopia) may go undetected until a person is in their late 30s or 40s when they need reading glasses slightly earlier than they otherwise would. A lot of times they have excellent uncorrected vision for many years before the farsightedness is discovered. This is due to the flexible lens of our eyes that allows the lens to do the work of the glasses. As the lens becomes less flexible in our 30s and 40s, eye strain becomes more prevalent and glasses are inevitable at some point.
Nearsightedness is a different story. Nearsighted children may have no difficulty at all reading because they are focusing muscles don’t have to work at all to see up close. Nearsighted children typically become nearsighted between ages 7 and 12. The severity of nearsightedness tends to increase into early adulthood, so the earlier a child develops nearsightedness the more severe it generally is. This is why many public health officials and ophthalmologists try to find causes of nearsightedness and develop solutions to slowing the progression of nearsightedness in children.
The question of farsightedness versus nearsightedness is hopefully fairly easy to understand at this point. Nearsightedness versus farsightedness presents fairly differently in childhood and can, in my opinion, affect personality, likes, and dislikes because near tasks are naturally easier for nearsighted versus farsighted children. Thus nearsighted and farsighted children have different views of the world.
-Dr. Matthew Sharpe