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Demystifying Eye Prescription: What Do OD and OS Mean


Introduction

Interpreting an eye prescription often involves symbols such as OD and OS which can be quite taxing to many people. These acronyms are crucial when it comes to identifying the correct vision correction for each eye, however, most people are unfamiliar with what they represent. In this guide, you will learn about the above-mention terms and their significance and other frequent abbreviations regarding your eye prescription.

OD vs. OS: What Did They Mean

OD vs. OS: What Did They Mean?

OD means “Oculus Dexter” which is Latin for right eye and OS means “Oculus Sinister” which is Latin for left eye. These latin terms are used in the prescription of glasses by eye care givers to reduce ambiguity.

  ● Which Eye Is OD vs. OS?

  To clarify:

  OD (Oculus Dexter) = Right Eye

  OS (Oculus Sinister) = Left Eye

      ● What are OU, OD and OS?

These terms assist in avoiding misunderstandings and prevent the wrong prescription from being administered to the wrong eye.

  -OD: The Right Eye

OD especially states exactly that whatever impairment was diagnosed (glasses or contact lenses) are for your right eye only. This may involve different levels of correction based on your eye’s health when the surgery takes place.

  -OS: The Left Eye

OS means that the prescription correction refers to eyesight in your left eye. Similarly, it makes sure that the right treatment is administered to the right place that requires it.

  -OU: Both Eyes

You will also find the abbreviation OU which is short for Oculus Uterque, which means both eyes. It is mainly rendered in cases where the prescribed treatment or medication is the same for both eyes.

  -Right Eye vs. Left Eye

This means that when it comes to food preparation, there should be no mixing of one type of food with another.

Thus, one of the most important considerations for an eye prescription is to make sure one does not interchange OD for OS and vice versa. I may have different prescription in each eye and putting the wrong lens in the wrong eye leads to blurring of vision or discomfort.

Glossary of Eyeglass Prescription Abbreviations and Terms

Glossary of Eyeglass Prescription Abbreviations and Terms

Besides OD and OS, there are many other acronyms that appear on your prescription. Here’s a glossary of common terms:

  ● SPH (Sphere): 

This value indicates the extent of myopia or hyperopia, which is the inability to see objects far away or nearby without help. A negative sign (-) is used to describe near sightedness, while a positive sign (+) is used to describe far sightedness.

  ● CYL (Cylinder): 

This shows the level of astigmatism in your eyes. Astigmatism is an eye irregularity where the cornea or lens is not spherical and results in a blurred vision.

  ● Axis: 

The axis shows you the position of astigmatism, with values ranging from 0 to 180 degrees.

  ● Add: 

This stands for Addition, it is used to describe the third number that is added to the distance vision prescription in bifocal or multifocal glasses to facilitate reading or any near work.

  ● BI, BO, BU, or BD: 

The meanings of these abbreviations pertain to prism correction employed for patients with eye alignment deviations. They mean:

  - BI: Base In

  - BO: Base Out

  - BU: Base Up

  - BD: Base Down

  ● PD (Pupillary Distance): 

pupillary distance is a distance between the centers of eyes, more specifically, between the front facets of the lenses of your eyes. This helps to align the lenses well to minimize distortion.

Why Understanding Your Prescription Matters?

As you are writing the abbreviations in your eye prescription like OD and OS, it is important to know the meaning to ensure you get the right glasses. When you understand what each term is, then mishaps such as placing the wrong lens can lead to either discomfort or blurry vision. Also, being informed makes you get better questions to ask the eye doctor during eye examinations, to have all your vision needs met. It also helps you make wiser decisions when buying glasses or contact lenses – giving you the best vision correction possible.

Common Lens Type Abbreviations of Glasses Lens

Common Lens Type Abbreviations of Glasses Lens

There are several abbreviations related to the type of lenses prescribed:

  ● SV (Single Vision): 

Bifocals help correct two fields of vision, a distance vision and a close vision, with the upper portion of the lens correcting the distance vision and the lower portion correcting the near vision.

  ● BF (Bifocal): 

Bifocal lenses consist of two separate regions for viewing distant objects and for reading.

  ● TF (Trifocal): 

Bifocal lenses provide for correction of vision in three areas of distance, intermediate and near vision.

  ● PL or PAL (Progressive Lens): 

Bifocals are glasses that have two different prescriptions in which the distance vision prescription is marked by visible lines at the top, while the prescription for near-vision is found towards the bottom of the lenses.

Contact Lens Prescription Abbreviations

It is also important to note that contact lens prescription is slightly different from glasses prescription. Some unique terms include:

  ● BC (Base Curve): 

The base curve describes the geometry of the contact lens that corresponds to the shape of the wearer’s eye to ensure comfort.

  ● DIA (Diameter): 

Diameter defines the size of the contact lens from one side to the other since the lens has to cover a particular area of the eye.

Clearing Up Common Misconceptions

It is crucial to identify the correct meaning behind these abbreviations like OD, OS, etc. Let’s debunk a couple of common misconceptions:

Misconception 1: “OD” Means Ocular Dominance

A common misunderstanding of OD is that it is a measure of the eye preference for visual processing or how much one eye is favored over the other. However, OD is not about right eye dominance but rather, is an acronym for œoutler öer right eye, œder öer right eye, œdominant öer right eye and œod ó optical dominance ó right eye.

Misconception 2: Universality in Languages

Thereby, it is also possible to think that OD and OS abbreviations are the same for all languages which is untruthful. They are very typical in areas of medicine where Latin terminology is applied, but may not be as widespread in other parts of the world that are not westernised.

Your Eyeglass Prescription Isn’t Your Contact Lens Prescription

One frequently confused issue is a confusion of your eyeglass prescription with that of contact lenses. On the contrary, they are not. They also note the measurements of BC (base curve) and DIA (diameter) to ensure the contact lens blends in with the shape of your eye.

Conclusion

The knowledge of what the individual letters such as OD, OS, OU, among other vision prescription signs enhances your vision care. This is important as it assures that your prescription is correct and appropriate for your condition. When optometrists or ophthalmologists are explaining the part of your eye prescription or presenting corrective lenses, this knowledge can make one comfortable with eye condition.

Frequently Asked Questions

What is the OS size of sunglasses?

OS is not a size for sunglasses, but it is an abbreviation for the Latin term oculus sinister, which means "left eye".

What is the difference between OD and OS doctors?

"OD" stands for "oculus dexter" which means "right eye" in Latin, while "OS" stands for "oculus sinister" which means "left eye" in Latin; essentially, they are not different types of doctors, but rather abbreviations used on an eye prescription to indicate which eye the measurement pertains to - "OD" for the right eye and "OS" for the left eye.


What is the normal eyesight for left and right?

"Normal eyesight" for both the left and right eye is typically considered to be 20/20 vision which means you can see clearly at 20 feet what a person with normal vision should be able to see at that distance; essentially, this is the standard for "normal" vision in most situations.

Are OD and OS contacts different?

Yes, OD and OS contacts are typically different because each eye may require a unique prescription. The contact lenses for the OD (right eye) and OS (left eye) will have different powers to correct vision accurately for each eye.

Is 5.5 eyesight legally blind?

Yes, a visual acuity of 5.5, which is equivalent to 20/400, is considered legally blind. However, other factors are also considered when determining legal blindness, such as visual field. For example, someone with a visual acuity of 5.5 may not be considered legally blind if their visual field is normal.

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