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Understanding Eye Power: Myopia, Hyperopia, Astigmatism, and Beyond

Category : 
Author : Dr Deepak Garg
Amblyopia / Astigmatism

We understand that vision health is of utmost importance to everyone, and we are here to provide you with the answers you seek. This guide will address the common eye power-related questions that we frequently receive.

1. What Does Having Eye Power Mean?

Having eye power means your eyes have a shape such that the rays of light do not focus on the back part of the eye called the retina. Thus, to make them focus on the retina, you need specific lenses in front of your eyes, either spectacles or contact lenses. The power of the eye is denoted by the power of the lens used to make you see clearly. The power of the eye can be of three types: Plus number or hyperopia, minus number or myopia, and cylindrical number or astigmatism.

2. What Does Negative Eye Power Mean?

Negative eye power means you need a negative lens or a minus-powered lens to make the rays of light focus on the retina. In other words, a minus-numbered lens will help you see clearly. This type of power is found in individuals complaining of having blurry distance vision. The medical term for negative eye power is Myopia, and it has become a topic of interest in recent years because it is expected that half the world’s population will have negative eye numbers by 2050. This is the most common type of eye power seen in the population. The eye number can progress, and there are certain tools available to help reduce the risk of this progression. It is also a common reason why people undergo Lasik eye surgery or Clear lens extraction.

3. What Does Positive Eye Power Mean?

Like negative eye power, positive eye power means you need a positive or plus-powered lens to focus the rays of light on the retina. This type of power is found in individuals complaining of blurry near vision. The medical term for positive eye power is Hypermetropia. Although it is not considered as big a concern as negative power, if undetected at a young age, it may cause a condition known as lazy eye or amblyopia. All humans are born with around +2.00 numbers, which is why eye doctors put certain drops in babies to determine their exact power and decide on the prescription that should be given, if needed.

4. What Does Cylindrical Power Mean?

Cylindrical power arises when the shape of the cornea, the frontmost layer of the eye, is like an oblate rugby ball shape, instead of being a regular spherical shape. This shape causes the power to be manifested only in a particular orientation called the axis. It does not mean that the eyes are weak or that there is a defect; it simply means the eyes have such a shape that the person needs a cylindrical number to see clearly. 

Abnormally high cylindrical numbers (>3.00) may indicate a condition called keratoconus, so the patients who have cylindrical eyesight of greater than 3 diopters undergo a test called topography once a year to make sure they have not developed keratoconus.

5. What Does Spherical Number in the Eye Mean?

Spherical power means the rays of light are not getting focused on the retina. They are either getting focused in front or at the back of the eye. Here, the shape of the cornea is regular, and the blur that the individual sees is a complete blur instead of the glare and shadowing effect seen in cylindrical power. Both Myopia and hyperopia are types of spherical powers.

6. What Does 6/6 Mean?

6/6 (read as 6 by 6) is a notation used in eye care to quantify your vision. “6” in the numerator stands for 6 meters, which is the testing distance, i.e., how far you are sitting when your eye test is being performed. The denominator denotes the ideal distance at which a person with no eye power must be able to see the line. Thus, ideal vision is 6/6 or 20/20. 20 refers to 20 feet, which is equal to 6 meters. It means that a person can see letters from a distance of 6 meters, which they are supposed to see from a distance of 6 meters. 6/9 means that a person can see letters from a distance of 6 meters, which they are actually supposed to see from a distance of 9 meters. 6/12 means that a person can see letters from a distance of 6 meters, which they are actually supposed to see from a distance of 12 meters, and so on. 

7. My Eye Doctor Prescribed Me Powered Glasses. What Does It Mean?

Depending on your eye power, your eye doctor will prescribe you to wear either negative or positive power glasses. The lenses in your spectacles or contact lenses will have the power to help you see better. You could have a spherical power or a cylindrical power. The spherical power could be a plus power or a minus power.

Some Common Specific Questions 

People ask us specific questions about their eye powers most of the time. One of these questions is, 

  • What does 0.25 eye power mean?
  • What does 0.5 eye power mean?
  • What does 0.50 eye power mean?
  • What does 0.75 eye power mean? 
  • What does 1.25 eye power mean? 
  • What does minus 2 eye power mean?

I will answer all together. 

When one has eye power, they can’t see clearly without glasses. The rays of light entering the eye are not focusing on the retina because either the eye is longer or shorter than normal. In other words, the shape is not the perfect shape that the eye should be.

To see clearly, we have to do something which will focus the rays of light on the retina, and we achieve this by giving lenses. Lenses could be in the form of spectacle lenses or contact lenses. 

0.25, 0.5, 0.75, and 1.25 are different eye powers, and it means that you have to wear lenses of these powers so that you see clearly. It does not mean that your eyes have a defect or are weak; it only means that the shape of the eye is slightly different than what it should ideally be. 

A person with an eye power of 5 or -5 has an eye that is much longer than somebody who has a power of -1 or -2. Similarly, a person having a power of -7 has an eye that is much longer than a person who has a power of -5.

PRO TIP: 0.25 and 0.50 are considered very small numbers, and there is a high chance that a person with such numbers would be able to see almost everything without glasses too. Not wearing glasses is not going to harm your eyes in any way, so if you prefer not to wear glasses for such small numbers, it is totally okay to do so.At Eye Solutions, we specialise in providing comprehensive eye care services, ranging from thorough eye examinations to advanced surgical procedures, in Mumbai & Chennai. In case you are facing any “Eye Conditions,” we urge you to schedule an appointment with our esteemed eye hospital in Mumbai & Chennai, where our top-notch team of eye specialists is ready to assist you.

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26 comments on “Understanding Eye Power: Myopia, Hyperopia, Astigmatism, and Beyond”

  1. So, what if when I stay indoors for long and come outside when is sunny and I can open my eyes well?
    When I force to open it, there will be tears coming out from my eyes.

    1. You are not expected to look at the sun. I think if anyone looks at the sun their eyes will water. If you do have excessive watering you might have dryness and maybe consult an ophthalmologist.

  2. Hello Doc, many years ago my eye doc prescribed me -0.25 and -0.50/75 power for glasses. But I didn’t wear any glasses until now. Currently the power has increased. On my right eye it’s -1.00 (15° axis) and on my left eye it’s -1.50 (165° axis). Should I constantly use glasses or the power will keep increasing if I don’t use glasses?

  3. I went for an eye clinic today and my results are as stated:

    CYL— OD -0.25 axis 180 degrees
    OS -0.50 axis 170 degrees

    They say I have astigmatism and that I need glasses for it. But when I searched for it in the Internet it says I have mild astigmatiosm and it does not need any glasses for it. But my mild astigmatism has symptoms, I keep experiencing headaches, nausea, anxiety and I feel like the ground is moving when I walk, eye ache at my eyelids esp when exposed to sun. Should I go with what they said or not wear glasses?? Oh and the SPH region says plano

  4. my SPH number for right eye is -1.25 and left eye is -0.75 and CYL number for both eyes is -3.25 axis 180. But, i am not able to see clearly through glasses object is getting distorted and blugy. what’s the issue?

  5. Hello Sir mera right And left eye ka number -1.55 he to sir ye vision jaise 6/6 hota he to ye -1.55 ka kitna _/_ hoga?

  6. I have minus 2.5 spherical and 1 cylinder number in right eye, minus 3 spherical and 0.75 cylinder number in left eye.

    Is it ok to wear only minus 3 spherical number in both eyes?

    1. Yes its ok. You may have headaches which may range from mild to severe. If you get headaches then you might have to wear the cylinder.

      but you are not benefitting in any way by wearing only -3. might as well wear your entire power.

  7. I realised I may need progressive lens recently. My current power is Right eye -5.75, Cyl -0.50, Add +0.50. Left eye -4.75, add +0.50. I have eye checkup at eye centre and optical shop.

    Eye centre’s new power is right -5.75, cyl -0.50, add + 1.75; left -4.50, add +1.75.

    Optical shop Right -6.25, cyl 0.00, add +1.75; left eye -4.50, cyl -0.25, add + 1.75.

    Can I check which power of progressive lens is better for eye and give better clarifty with lesser distortion? with astigmatism (eye centre) or without astigmatism (optical shop).

    1. Dear Amelia,
      You wont be able to check which eye power is better on your own.

      If you are based in mumbai we can do an eye check up and suggest which progressives you should get for your eye and your requirements.


  8. hello doctor, my both eye sph +0.50 and cyl is +2.75. right eye axis is 75 and left eye is 90. but I can see blurry through left eye. I checked up last week. is there any problem?

    1. WWhere did you get an eye check up ?

      Also i might not be able to tell you if there is a problem or not by these few lines. We will need to examine you in detail to comment.

  9. hello sir! I just recently got my eyes checked my soh for left and right eye is -3.75 and the cyl is -1.25 for both eyes so if I total both it becomes -5.0 (sph+cyl) I’m not sure about it can you let me know is it a high number or not ? and what can I do to reduce it without surgery

  10. Sir, I recently got my eyesight checked, and they recommended 0.50 glasses for me.Should I wear glasses or it’s okay if I don’t wear it.Is there a chance that my eyesight will completely recover if I don’t wore glasses?what I have to do to completely recover my eyesight..

  11. I am 29 years old. I checked my eyes from opthalmologist…he said that I have 1.5 and 1.75 cylindrical eye number in right and left eyes respectively. but I don’t feel any discomfort such as blurry vision etc. some time I feel like headache and eye strain when I watch more mobile i.e. more screen time. I am very tensed. is it very critical situation? can cylindrical numbers can be reduced or removed?

    1. Cylindrical numbers dont go away on their own. THey can however be removed by laser. the procedure is called Lasik

      as long as the cylindrical number is not increasing you dont need to worry.

  12. Hello sir.. I have keratoconus in my left eye and did c3r.. I have blurry vision in my left eye and I couldn’t see anything clearly with my left eye…But with my right eye I can see things properly. My Doctor suggested me to use contact lenses for my left eye and they said i have power 5… My question is will my vision improve if I use contact lenses?

    1. Dear Kaviya,

      these are special contact lenses known as scleral lenses. and yes there is a very high possibility that as soon as you try them on you will see much better.

      What you should do is come to Eye SOlutions for a trial which means you will get to know if contact lenses help you or not.

  13. my son has regressed rop at birth and now he is 2.5 years. we didn’t observe any eye issues with him during his regular activities but during his routine check up we come to know he has spect for both eyes with spherical +0.5 and cylindrical -2 with axis 140 so want to ask is it nearsighted/ farsighted or both (please explain his prescription) and whether it will reduced as he grows (As in blog it is mentioned all children born with +2)and 24*7 wearing of glasses essential

    1. He basically has a cylindrical power or what is also known as astigmatism. He will have to wear glasses most of the time. The number will not reduce and most likely will not increase either.