How Do You Read a Glasses Prescription

How to Read Your Eyeglasses Prescription

Making sense of your eye prescription chart

The numbers on your eyeglass prescription relate to the shape of your eyes and forcefulness of your vision. They tin can help you figure out whether you have nearsightedness, farsightedness or astigmatism — and to what degree.

If y'all know what to look for, you can make sense of the numbers and abbreviations on your prescription chart.

OD vs. Os: I for each center

Heart doctors utilise the abbreviations "OD" and "OS" to denote your right and left eyes.

Your eye doctor may requite you lot a paper prescription that looks something like this.

• OD is your right eye. OD is short for oculus dexter, the Latin phrase for "right eye."

• OS is your left eye. Os is short for oculus sinister, Latin for "left eye."

Your vision prescription may also have a column labeled "OU." This is the abbreviation for oculus uterque, which means "both optics" in Latin.

These abbreviated terms are common on prescriptions for glasses, contact lenses and center medicines, but some doctors and clinics have opted to modernize their eye prescriptions by using RE (right eye) and LE (left eye) instead of OD and Os.

The information for your right center (OD) e'er comes before the data for your left center (Bone). Eye doctors write prescriptions this way considering, when they confront you, they meet your correct center on their left (outset) and your left eye on their right (second).

Sphere (SPH)

Sphere indicates the amount of lens power prescribed to correct nearsightedness or farsightedness. Lens power is measured in diopters (D).

• If the number nether this heading comes with a minus sign (–), you are nearsighted.

• If the number under this heading has a plus sign (+), you are farsighted.

The term "sphere" means that the correction for nearsightedness or farsightedness is "spherical," or equal in all meridians of the eye.

Cylinder (CYL)

Cylinder indicates the amount of lens power needed for astigmatism. Information technology always follows the sphere power on an eyeglass prescription.

The number in the cylinder column may accept a minus sign (for correction of nearsighted astigmatism) or a plus sign (for farsighted astigmatism).

If null appears in this column, you either don't take astigmatism, or your degree of astigmatism is so small that it doesn't demand to be corrected.

The term "cylinder" ways that this lens power added to right astigmatism is non spherical, but instead is shaped and then ane acme has no added curvature, and the tiptop perpendicular to this "no added power" pinnacle contains the maximum power and lens curvature to right astigmatism.

Meridians of the eye are determined past superimposing a protractor scale on the centre's front surface. The 90-degree meridian is the vertical meridian of the middle, and the 180-caste meridian is the horizontal summit.

Meridians of the centre are determined by superimposing a protractor scale on the center's front surface. The ninety-degree meridian is the vertical peak of the centre, and the 180-caste meridian is the horizontal pinnacle.

Axis

Axis describes the lens meridian that contains no cylinder power to correct astigmatism.

If an eyeglass prescription includes cylinder power, it also needs to include an axis value, which follows the cylinder ability.

The axis is defined with a number from 1 to 180.

• The number 90 corresponds to the vertical meridian of the eye.

• The number 180 corresponds to the horizontal summit of the eye.

The centrality is the lens pinnacle that is 90 degrees away from the meridian that contains the cylinder power for astigmatism correction.

Add together

"Add" is the added magnifying power applied to the bottom role of multifocal lenses to correct presbyopia — the natural farsightedness that happens with age.

The number appearing in this section of the prescription is always a "plus" power, even when you don't see a plus sign. Generally, it will range from +0.75 to +3.00 D and will exist the same ability for both optics.

Prism

This is the corporeality of prismatic power, measured in prism diopters ("p.d." or a triangle when written freehand), prescribed to recoup for eye alignment issues.

Only a modest percentage of eyeglass prescriptions include a prism measurement.

When present, the amount of prism is indicated in either metric or fractional English units (0.5 or ½, for example), and the direction of the prism is indicated by noting the relative position of its "base of operations" (thickest edge).

Four abbreviations are used for prism direction: BU = base up; BD = base down; BI = base in (toward the wearer's nose); BO = base out (toward the wearer's ear).

How they're measured

Sphere ability, cylinder ability and add power always appear in diopters. They are in decimal form and generally are written in quarter-diopter (0.25 D) increments.

Centrality values are whole numbers from one to 180 and signify merely a meridional location, not a power.

When prism diopters are indicated in decimal course, typically only one digit appears after the period (e.k., 0.5).

An example eye prescription chart

Still confused? Let's await at an example prescription nautical chart:

	SPH	CYL	Centrality	Add	Prism
OD	-2.00	SPH		+2.00	0.5 BD
Os	-one.00	-0.fifty	180	+two.00	0.5 BU

In the right eye (OD), the center doctor prescribed:

• -2.00 D sphere for the correction of nearsightedness.

• No cylinder power or axis, which means no astigmatism is present. This doctor chose to write "SPH," to ostend the correct heart is beingness prescribed but spherical power. Some doctors will add "DS" for "diopters sphere" and others will go out it bare.

The left heart (Bone) was prescribed:

• -1.00 D sphere for nearsightedness correction.

• -0.50 D cylinder for the correction of astigmatism.

• A cylinder power with an centrality at the 180 meridian. This means that the horizontal (180-degree) superlative of the heart has no added power for astigmatism and the vertical (ninety-degree) meridian gets the added -0.50 D from the cylinder column.

Both eyes were prescribed:

• An "add ability" of +two.00 D for the correction of presbyopia.

• Prismatic correction of 0.5 prism diopter in each heart. In the right eye, the prism is base downwards (BD); in the left eye, it's base upwards (BU).

Your eye doctor may also write specific lens recommendations on your eyeglass prescription. They might suggest anti-cogitating coating, photochromic lenses and/or progressive lenses to give y'all the virtually comfortable vision correction possible.

Encounter RELATED: How "bad" is my prescription?

Can eyeglass prescriptions exist used to buy contact lenses?

No, you cannot utilise your spectacles prescription to buy contact lenses.

An eyeglass prescription just works for the purchase of eyeglasses. It does non contain certain data that is crucial to a contact lens prescription.

That data can but be obtained through a contact lens fitting, an additional process that can be performed during your eye doctor visit.

Eyeglass lenses are positioned at a altitude from the eyes, while contacts residue straight on the eyes. That distance affects the lens power required for eyes to focus properly.

In addition to the information in an eyeglass prescription, a contact lens prescription must specify the base (cardinal) curve of the back surface of the contact lens, the lens diameter, and the specific manufacturer and brand name of the lens.

Also, the power of an eyeglass prescription frequently is modified when determining the best contact lens ability. This is because eyeglass lenses are worn some distance (commonly about 12 millimeters) from the surface of the eye, whereas contact lenses rest directly on the cornea of the eye.

An accurate contact lens prescription tin be written only after a contact lens plumbing equipment has been performed and the prescribing doctor has evaluated your optics' response to the lenses and to contact lens article of clothing in general.

SEE As well: Contact lens vs. eyeglasses prescriptions

Your eyeglass prescription is yours to keep

The Federal Trade Commission (FTC) is the U.S. government's consumer protection agency. Their Prescription Release Rule requires that eye doctors requite patients a copy of their eyeglass prescription at the end of an eye exam that includes a refraction.

The Prescription Release Rule is intended to allow the "portability" of your eyeglass prescription, giving you the liberty to purchase glasses from any vendor of your choice.

Your eye doctor must give y'all a copy of the prescription whether or non yous ask for it. Middle doctors may non condition the release of your prescription on your agreement to purchase eyeglasses from them, nor may they charge y'all an extra fee to release your prescription.

If y'all think your eye doctor has violated this dominion, you can report the problem to the FTC.

Page published in February 2019

Page updated in Feb 2022

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Source: https://www.allaboutvision.com/eyeglasses/eyeglass-prescription.htm

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