You might just be wondering what 0 means for glasses, or you might had a prescription and you are wondering why you had 0 prescription but you are being required to wear one. So this article is about why this usually happens and what’s the plan of action when receiving this kind of prescription.
The usual meaning behind having a 0.00 in glasses and contacts is that there is no spherical power needed for your prescription. This means that there is a chance that you have other condition which might need a prescription. The most common among which is cylindrical correction or for astigmatism.
For some, it is the reverse. They will have 0 prescription in cylindrical and will have something in spherical. The cause for this might be either myopia(nearsightedness) or hyperopia(farsightedness)
What does 0.00 SPH mean in eye prescriptions?
Having a 0.00 spherical or SPH in your eye prescriptions mean that your eyeballs are normal in shape or perfectly spherical. This means that you are not nearsighted or farsighted since there are no errors in the shape of the eyeball. An eye prescription despite 0.00 spherical might mean that there are other things to look out for aside from the shape of your eyeball.
The most common reason a person might still get glasses even at 0 spherical is that they have cylindrical error. Commonly known as astigmatism.
Astigmatism is an error not in the shape, but the curvature of the eyeball. People with astigmatism have an eyeball shaped more like a football shape because of the change in curvature.
The increasing amount of astigmatism is how much your eyeball is shaped like a football.
It is also common to see people without any nearsightedness or farsightedness but have astigmatism. That’s why people can usually have 0.00 SPH and have a cylindrical error. That’s why they need glasses.
In the need for glasses, a study from the World Opthalmology Congress concluded that as little as 1.00 diopters in can cause a significant decrease in a person’s quality of life. This is because there is a big difference between astigmatism and spherical errors.
Source: Wolffsohn, James S., et al. “Effect of Uncorrected Astigmatism on Vision.” Journal of Cataract and Refractive Surgery, vol. 37, no. 3, 2011, pp. 454–60. Crossref, doi:10.1016/j.jcrs.2010.09.022.
The biggest difference is that spherical errors is affected by distance. For example, if you are nearsighted, you can still see clearly, if objects are near and the opposite goes for farsighted. (Seeing things clear if objects are far)
However, if you talk about astigmatism, it blurs object at any distance. That’s why even as little as 1.00 diopters can change a person’s quality of life significantly.
If you are interested in what people with astigmatism see, you may check this article. It is also packed with visuals so you can check see what a person with astigmatism can see: What do people with astigmatism see?
What does 0.00 CYL mean in eye prescriptions?
A 0.00 cylindrical or CYL in eye prescriptions mean that the person has no astigmatism because there is no cylindrical error. The most common reason for having an eye prescription even at 0.00 cylindrical is because they might have a spherical error in which the shape of the eyeball is either elongated or short.
Not all people who have 0.00 means that it is in spherical. In fact, many people have 0 astigmatism and have a spherical error.
This means that people in this category have 0.00 cylindrical error which means they don’t have astigmatism but they are either nearsighted or farsighted.
In nearsightedness, eyeballs are elongated thus the light is focused in front of the retina. Thus, object that are far away become blurry. People in this category are usually prescribed with negative lenses or myopia glasses which expand the light.
Farsightedness on the other hand have eyeballs that are short. Because of this, light is focused behind the retina. In this condition, near objects become blurry. People with hyperopia are prescribed with positive lenses or reading glasses which focuses light so it can hit the retina accurately.
There is another cause of farsightedness which is called presbyopia. Presbyopia happens not because of the shape of the eyeball, but because of the lens not being as flexible as it is. This usually happens in aging and it usually starts with people in their 40s.
Can you have a 0 Spherical and 0 Cylindrical Prescription Glasses?
It is possible to have both 0 spherical and 0 cylindrical prescription and it usually happens when a person is being prescribed to wear anti-radiation or glasses with tints for sun protection. This is usually being prescribed to people who have very sensitive eyes.
While the glasses won’t correct any refractive errors, there are glasses that help people who are sensitive to certain conditions such as radiation and sunlight.
These are glasses that will protect the eyes from harm as there are studies indicating that too much UV rays from the sun or radiation can cause some problems to your eyesight.
What’s the lowest prescription for glasses?
The lowest prescription for glasses is based upon what type of correction it does. Reading or Positive Glasses usually have +1.00 Diopters as its lowest strength while astigmatism and negative or myopia glasses can be as low as 0.25 diopters(astigmatism) and -0.25 diopters(myopia).
Here is a table summary of the lowest prescription glasses
|Positive lenses, Reading glasses||+1.00 Diopter|
|Negative Lenses||-0.25 diopters|
You might be wondering why reading glasses usually have +1.00 as its lowest compared to astigmatism and negative lenses.
While the interval for them is usually the same at 0.25. example: 0.25, 0.50, 0.75, 1.00, reading glasses usually start at 1.00.
The reason for this is because farsightedness usually starts causing a decrease quality of life at +2.00 diopters.
Here is a table summary on the different levels of farsightedness or hyperopia and the difference between them.
|Less than +2.00 Diopters||Low Hyperopia||Can still see clearly even without Correction|
|+2.25 to +5.00 Diopters||Moderate Hyperopia||Unable to see very clearly without Correction|
|More than +5.25 Diopters||High or Severe Hyperopia||Vision severely distorted and must always need Correction|
In summary, at low hyperopia or farsightedness, people can still live normally without glasses. This is because they can still usually read the standard size of texts which is about font size 12 in times new roman.
For more information of this, I have made an article discussing the strength of reading glasses where it summarizes all in greater detail. What does my reading glass tell about my eyes?
However, this is talking about the common or usually the over the counter prescription lenses. You may still find a very low grade one depending on your situation and check-up with a specialist.
On the other hand, astigmatism and myopia can start at 0.25 and -0.25 respectively.
Are Eye Prescriptions Bad?
Eye prescriptions are not bad. They are there to restore your vision back to 20/20. A proper eye prescription also prevents unwanted eye strain which may lead to many discomforts such as headaches and dizziness. They also increase the quality of life of an individual.
The problem with people who don’t wear glasses especially when their prescription is high is their eyes are working more just to focus on things which may lead to eye strain.
Another is that since their vision is low, their quality of life is severely decreased. It may affect their day to day lives and work. Especially people who work in a detail oriented environment.