Is an Eyeglass Prescription the Same for Reading and Distance

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 strength of your vision. They can aid you figure out whether y'all have nearsightedness, farsightedness or astigmatism — and to what degree.

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

OD vs. Bone: One for each eye

Eye doctors use the abbreviations "OD" and "OS" to announce your right and left eyes.

Your eye medico may give you a paper prescription that looks something like this.

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

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

Your vision prescription may besides have a cavalcade labeled "OU." This is the abbreviation for oculus uterque, which means "both eyes" in Latin.

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

The information for your right center (OD) always comes earlier the data for your left heart (OS). Center doctors write prescriptions this manner considering, when they face yous, they see your correct eye on their left (first) and your left eye on their right (second).

Sphere (SPH)

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

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

• If the number nether this heading has a plus sign (+), you lot 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 ability on an eyeglass prescription.

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

If zero appears in this column, you either don't have astigmatism, or your degree of astigmatism is and then pocket-sized that it doesn't need to exist corrected.

The term "cylinder" means that this lens power added to correct astigmatism is not spherical, just instead is shaped so one meridian has no added curvature, and the meridian perpendicular to this "no added ability" meridian contains the maximum power and lens curvature to correct astigmatism.

Meridians of the eye are adamant by superimposing a protractor scale on the heart'southward front surface. The 90-degree height is the vertical meridian of the eye, and the 180-degree meridian is the horizontal height.

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

Axis

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

If an eyeglass prescription includes cylinder power, it also needs to include an centrality 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 meridian of the eye.

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

Add

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

The number appearing in this section of the prescription is ever a "plus" power, even when y'all don't meet a plus sign. Generally, it will range from +0.75 to +3.00 D and will exist the aforementioned power for both eyes.

Prism

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

But a small percentage of eyeglass prescriptions include a prism measurement.

When present, the amount of prism is indicated in either metric or fractional English units (0.v or ½, for example), and the management of the prism is indicated by noting the relative position of its "base of operations" (thickest edge).

4 abbreviations are used for prism management: BU = base upwards; BD = base downwards; BI = base of operations in (toward the wearer's nose); BO = base out (toward the wearer's ear).

How they're measured

Sphere ability, cylinder power and add ability always announced in diopters. They are in decimal grade and by and large are written in quarter-diopter (0.25 D) increments.

Axis values are whole numbers from 1 to 180 and signify but a meridional location, not a power.

When prism diopters are indicated in decimal class, typically only one digit appears later the menstruum (e.g., 0.5).

An instance center prescription chart

Still confused? Let'south look at an example prescription chart:

	SPH	CYL	Axis	Add	Prism
OD	-ii.00	SPH		+2.00	0.5 BD
Os	-1.00	-0.fifty	180	+2.00	0.5 BU

In the correct eye (OD), the eye doc prescribed:

• -2.00 D sphere for the correction of nearsightedness.

• No cylinder ability or axis, which means no astigmatism is nowadays. This doctor chose to write "SPH," to confirm the right center is being prescribed only spherical power. Some doctors will add "DS" for "diopters sphere" and others will leave it blank.

The left eye (Bone) was prescribed:

• -1.00 D sphere for nearsightedness correction.

• -0.50 D cylinder for the correction of astigmatism.

• A cylinder power with an axis at the 180 meridian. This means that the horizontal (180-degree) meridian of the eye has no added ability for astigmatism and the vertical (90-degree) meridian gets the added -0.50 D from the cylinder column.

Both eyes were prescribed:

• An "add ability" of +2.00 D for the correction of presbyopia.

• Prismatic correction of 0.five prism diopter in each eye. In the right heart, the prism is base down (BD); in the left centre, information technology's base up (BU).

Your middle doctor may likewise write specific lens recommendations on your eyeglass prescription. They might advise anti-reflective coating, photochromic lenses and/or progressive lenses to requite you the near comfortable vision correction possible.

Come across RELATED: How "bad" is my prescription?

Can eyeglass prescriptions be used to buy contact lenses?

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

An eyeglass prescription but works for the purchase of eyeglasses. It does not contain sure information that is crucial to a contact lens prescription.

That information can only be obtained through a contact lens fitting, an boosted procedure that can be performed during your middle doctor visit.

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

In add-on to the information in an eyeglass prescription, a contact lens prescription must specify the base (primal) bend of the dorsum surface of the contact lens, the lens diameter, and the specific manufacturer and brand proper noun 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 (usually virtually 12 millimeters) from the surface of the middle, whereas contact lenses balance directly on the cornea of the heart.

An accurate contact lens prescription can be written only subsequently a contact lens fitting has been performed and the prescribing doc has evaluated your eyes' response to the lenses and to contact lens vesture in full general.

SEE ALSO: Contact lens vs. eyeglasses prescriptions

Your eyeglass prescription is yours to go along

The Federal Trade Committee (FTC) is the U.S. authorities's consumer protection agency. Their Prescription Release Rule requires that eye doctors give 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 y'all the liberty to buy glasses from any vendor of your choice.

Your eye doctor must give you a copy of the prescription whether or not yous ask for it. Heart doctors may not condition the release of your prescription on your agreement to buy eyeglasses from them, nor may they charge yous an extra fee to release your prescription.

If you call up your center doctor has violated this dominion, you lot tin can written report the problem to the FTC.

Page published in Feb 2019

Page updated in February 2022

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

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