How to Read Your Vision From Your Glasses

How to Read Your Eyeglasses Prescription

Making sense of your middle prescription chart

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

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

OD vs. OS: One for each eye

Eye doctors utilize the abbreviations "OD" and "Bone" to denote your right and left eyes.

Your center doc may requite you a newspaper prescription that looks something like this.

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

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

Your vision prescription may likewise have a column labeled "OU." This is the abbreviation for oculus uterque, which ways "both eyes" in Latin.

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

The information for your right center (OD) always comes before the data for your left eye (Os). Eye doctors write prescriptions this way because, when they face you lot, they see your right eye on their left (first) and your left centre on their correct (2nd).

Sphere (SPH)

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

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

• If the number under this heading has a plus sign (+), yous 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 ever 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 nothing appears in this column, you lot either don't accept astigmatism, or your degree of astigmatism is so small that it doesn't need to be corrected.

The term "cylinder" means that this lens ability added to right astigmatism is not spherical, just instead is shaped so 1 meridian has no added curvature, and the meridian perpendicular to this "no added power" meridian contains the maximum power and lens curvature to correct astigmatism.

Meridians of the heart are adamant past superimposing a protractor scale on the centre's forepart surface. The 90-degree pinnacle is the vertical meridian of the middle, and the 180-degree meridian is the horizontal meridian.

Meridians of the eye are determined by superimposing a protractor scale on the eye's front surface. The xc-degree height is the vertical meridian of the eye, and the 180-caste superlative is the horizontal meridian.

Centrality

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 power.

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

• The number 90 corresponds to the vertical superlative of the center.

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

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

Add together

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

The number appearing in this section of the prescription is always a "plus" power, even when you don't encounter a plus sign. Generally, it will range from +0.75 to +3.00 D and will be the aforementioned 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 recoup for middle alignment issues.

Just a minor percentage of eyeglass prescriptions include a prism measurement.

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

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

How they're measured

Sphere power, cylinder power and add ability 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 i to 180 and signify only a meridional location, not a power.

When prism diopters are indicated in decimal class, typically only 1 digit appears after the catamenia (e.thou., 0.five).

An case centre prescription chart

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

	SPH	CYL	Axis	Add	Prism
OD	-ii.00	SPH		+2.00	0.5 BD
Os	-1.00	-0.50	180	+ii.00	0.5 BU

In the right eye (OD), the eye md prescribed:

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

• No cylinder power or centrality, which means 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 "DS" for "diopters sphere" and others will get out it blank.

The left eye (OS) was prescribed:

• -one.00 D sphere for nearsightedness correction.

• -0.50 D cylinder for the correction of astigmatism.

• A cylinder power with an axis at the 180 elevation. This means that the horizontal (180-caste) meridian of the eye has no added power for astigmatism and the vertical (90-degree) acme 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 0.5 prism diopter in each eye. In the right eye, the prism is base down (BD); in the left center, information technology'southward base up (BU).

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

SEE RELATED: How "bad" is my prescription?

Tin eyeglass prescriptions be used to buy contact lenses?

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

An eyeglass prescription but works for the purchase of eyeglasses. It does non contain sure information that is crucial to a contact lens prescription.

That information tin can merely be obtained through a contact lens plumbing fixtures, an additional process that tin be performed during your center doctor visit.

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

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

Too, the power of an eyeglass prescription frequently is modified when determining the best contact lens power. This is considering eyeglass lenses are worn some distance (usually nigh 12 millimeters) from the surface of the eye, whereas contact lenses residue directly on the cornea of the centre.

An accurate contact lens prescription can be written only afterwards a contact lens fitting has been performed and the prescribing doctor has evaluated your optics' response to the lenses and to contact lens wear in general.

SEE Also: Contact lens vs. eyeglasses prescriptions

Your eyeglass prescription is yours to keep

The Federal Trade Commission (FTC) is the U.South. regime'south consumer protection bureau. Their Prescription Release Rule requires that eye doctors requite patients a copy of their eyeglass prescription at the stop of an middle exam that includes a refraction.

The Prescription Release Rule is intended to allow the "portability" of your eyeglass prescription, giving you the freedom to buy glasses from any vendor of your pick.

Your eye doctor must requite you a re-create of the prescription whether or not you ask for it. Eye doctors may not condition the release of your prescription on your understanding to purchase eyeglasses from them, nor may they charge you an actress fee to release your prescription.

If you think your eye doctor has violated this dominion, you can report the trouble to the FTC.

Page published in February 2019

Folio updated in February 2022

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