How Can I Read My Eyeglass 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 optics and forcefulness of your vision. They can help you lot figure out whether you have nearsightedness, farsightedness or astigmatism — and to what degree.

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

OD vs. OS: One for each center

Eye doctors utilise the abbreviations "OD" and "Os" to denote your right and left eyes.

Your eye doctor may give yous a paper prescription that looks something like this.

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

• OS is your left centre. Bone is short for oculus sinister, Latin for "left center."

Your vision prescription may also 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 spectacles, contact lenses and eye 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 middle (OD) always comes earlier the data for your left eye (Bone). Center doctors write prescriptions this fashion because, when they confront y'all, they see your right heart on their left (get-go) and your left eye on their correct (2nd).

Sphere (SPH)

Sphere indicates the amount of lens power prescribed to right 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. It always follows the sphere power on an eyeglass prescription.

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

If cipher appears in this column, you either don't accept astigmatism, or your caste of astigmatism is so small that it doesn't need to exist corrected.

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

Meridians of the middle are determined by superimposing a protractor calibration on the eye'south forepart surface. The 90-degree meridian is the vertical meridian of the eye, and the 180-caste tiptop is the horizontal meridian.

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

Centrality

Axis describes the lens height that contains no cylinder power to right astigmatism.

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

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

• The number 90 corresponds to the vertical summit of the centre.

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

The axis is the lens meridian that is 90 degrees abroad from the meridian that contains the cylinder power for astigmatism correction.

Add

"Add" is the added magnifying power practical to the lesser part 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 y'all don't meet a plus sign. Generally, it will range from +0.75 to +3.00 D and will be the same power for both optics.

Prism

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

Only 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 (0.5 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 of operations in (toward the wearer's nose); BO = base out (toward the wearer'southward ear).

How they're measured

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

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

When prism diopters are indicated in decimal course, typically just one digit appears later on the period (due east.g., 0.5).

An example center prescription chart

Still dislocated? Let's look at an case prescription chart:

	SPH	CYL	Centrality	Add	Prism
OD	-2.00	SPH		+ii.00	0.5 BD
Bone	-one.00	-0.l	180	+2.00	0.v BU

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

• -ii.00 D sphere for the correction of nearsightedness.

• No cylinder power or axis, which ways no astigmatism is present. This md chose to write "SPH," to confirm the correct eye is existence prescribed only spherical power. Some doctors will add together "DS" for "diopters sphere" and others will go out information technology blank.

The left eye (OS) was prescribed:

• -1.00 D sphere for nearsightedness correction.

• -0.50 D cylinder for the correction of astigmatism.

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

Both optics were prescribed:

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

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

Your middle medico may also write specific lens recommendations on your eyeglass prescription. They might propose anti-reflective blanket, photochromic lenses and/or progressive lenses to requite you the near comfy vision correction possible.

SEE RELATED: How "bad" is my prescription?

Can eyeglass prescriptions be used to buy contact lenses?

No, yous cannot use your glasses prescription to buy contact lenses.

An eyeglass prescription only works for the purchase of eyeglasses. Information technology does not contain certain information that is crucial to a contact lens prescription.

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

Eyeglass lenses are positioned at a distance from the eyes, while contacts rest 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 (primal) curve of the back surface of the contact lens, the lens diameter, and the specific manufacturer and brand name of the lens.

As well, the power of an eyeglass prescription frequently is modified when determining the all-time contact lens power. This is considering eyeglass lenses are worn some distance (unremarkably near 12 millimeters) from the surface of the heart, whereas contact lenses residue directly on the cornea of the eye.

An accurate contact lens prescription tin be written just after a contact lens fitting has been performed and the prescribing doc has evaluated your optics' response to the lenses and to contact lens clothing in full general.

SEE Besides: 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 buy glasses from any vendor of your choice.

Your eye doctor must give y'all a copy of the prescription whether or not you ask for it. Eye doctors may not status the release of your prescription on your agreement to purchase eyeglasses from them, nor may they charge you lot an extra fee to release your prescription.

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

Folio published in February 2019

Page updated in February 2022

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

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