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How to Read an Eye Prescription: 5 Sections Simply Explained

So you’ve just been to your local optometrist for a comprehensive eye exam, what’s next? You’ve been provided a piece of paper and likely want to know how to read an eye prescription and how bad your eyes are?

As a local optometrist based in Metrotown, Burnaby, when our patients visit us for an eye exam, our focus is on providing the highest levels of optometric service, expertise and clinical knowledge. We also make sure you are comfortable with how to read the prescriptions given to you. 

How Do I Interpret My Vision Prescription?

Before we jump into what each section of how to read an eye prescription means, as a general rule, the higher the numbers on your prescription, the worse your eyesight is and the stronger your prescription will be to provide the necessary correction. 

Mild: -0.50 to -3. Moderate: -3.25 to -5.00. High: -5.25 to -10. Extreme: greater than-10.

However, that’s not all there is to know in learning how to read an eye prescription. Read on for a simple breakdown of each section of your eye prescription and what impact it will have on your vision.

How to Read an Eye Prescription: OD vs. OS

Simply put, “OD” is your right eye and “OS” is your left eye. One memory trick is to think of “D” as referring to your dominant side, which for 85-90% of people in Western countries is the right side. Also the right eye (OD) will always be listed above your left eye (OS).

How to Read an Eyeglasses Prescription
Oculus dexter = right eye. Oculus sinister = left eye.

How to Read an Eye Prescription: What Does Sphere Mean on an Eye Test?

Spherical refractive error determines whether your eyes are nearsighted or farsighted. When your distance vision is blurry, this is known as nearsightedness. This can occur when our eyeballs grow too quickly for an extended period of time during childhood and can continue worsening into our teens and even early adulthood.

Why does it matter? Clear vision is dependent on the size and shape of your eyeball! If your eyes are not symmetrically circular in shape, or too big or too small in size, light is unable to correctly focus on your retina. This results in blurry and distorted vision. 

Minus (-) powers means the prescription is nearsighted.

Nearsightedness (myopia) makes far-away objects look blurry.

Plus (+) powers means the prescription is farsighted.

Farsightedness (hyperopia) makes nearby objects look blurry.

How to Read an Eye Prescription: What is Cylinder and Axis?

Both these numbers describe astigmatism. Why is this important? 

Astigmatism is a common refractive error that causes your eyes to not clearly focus on images. This can result in blurry vision in the distance and at near. Astigmatism occurs when the eyeball shape is more oval than round. If you are struggling with blurry vision, headaches, glare or eye strain, it is time to get your eyes checked. 

Cylinder quantifies the severity of the astigmatism.

Axis is the direction of astigmatism.

How to Read an Eye Prescription for Your Astigmatism Axis

Horizontal (180) Focus 

  • Writing is blurred at the edges
  • It’s more clear in the middle
  • It appears as if the letters are moving
Astigmatism Axis

Vertical (090) Focus

  • Writing is blurred in general
  • Nothing is clear
  • It appears as if the letters are moving
Astigmatism Axis

Curious about treatments and 5 common myths? Our myopia management certified, and award-winning optometrist, Dr. Shaun Pati, debunks the top 5 myths about myopia treatments and recommends 3 treatments.

Do I Need Progressive Lenses? “ADD” on Eye Prescriptions

Your prescription will show a number in the ADD (addition) column if you need progressive lenses, also known as multifocal lenses. This type of prescription means that your optometrist has given you three focus zones in one pair of glasses. It’s incredibly helpful if you have nearsightedness or farsightedness with presbyopia. A progressive lens eliminates the need to switch between glasses when performing close-up work (such as reading a book), intermediate-distance work (like working on a computer), and distance viewing (like driving). 

How to Read an Eye Prescription: Is it bad? (What’s Considered Legally Blind)

Legal blindness is a level of blindness that has been defined by law to limit certain activities for safety reasons. These activities include driving, or determining eligibility for disability-related government programs and benefits. Someone is considered to be legally blind when visual acuity is 20/200 or worse in the better eye after correction, and/or a visual field of 20 degrees or narrower. 

Learning how to read your eye prescription is important because the higher your prescription is, the worse you will see without correction. In general, without corrective lens use, a -1.00 prescription results in 20/40 acuity, a -3.00 prescription results in 20/160 acuity and a -5.00 prescription results in 20/400 acuity.

How Bad is a +1.00 Eye Prescription?

So a +1.00 and -1.00 refractive error is quite modest; your eyesight isn’t too bad, as you only need 1 diopter of correction. On the other hand, +4.50 and -4.50 represents a greater lack of clarity; you’ll need a stronger prescription to achieve clear vision. 

How to Read an Eyeglasses Prescription

What Does +3.00 Vision Look Like?

Without correction, farsightedness (hyperopia) means distance and near vision can be blurred and this will have a notifiable impact on your vision.

How to Read an Eyeglasses Prescription

What Does -5.25 Vision Look Like?

Without correction, nearsightedness (myopia) means distance vision is blurry. Your near vision will be clear but you will have to hold objects fairly close to your eyes to see it clearly.

How to Read an Eye Prescription

Can Astigmatism Get Worse?

Astigmatism can be genetically passed on or it can be acquired by prolonged near work or excessive eye rubbing. Eyecare professionals can slow or even stop progression if it is caught in time. Astigmatism can get worse over time if left untreated. This is because without treatment, the skewed angle at which light enters your eye worsens, resulting in increasingly blurred and unclear vision.

Contact lenses could be an option for you. Find out if you are suitable for a contact lens fitting.

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