What is an Eyeglasses Prescription?
A glasses prescription is a document issued by an eye doctor that specifies the type and strength of glasses or contact lenses that are needed to correct a person's vision. It typically includes several key pieces of information, including:
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Sphere (SPH): This is the measure of the amount of lens power needed to correct for nearsightedness or farsightedness. It is measured in diopters (D) and is typically a positive or negative number. A positive number indicates farsightedness, while a negative number indicates nearsightedness.
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Cylinder (CYL): This is the measure of the amount of lens power needed to correct for astigmatism, which is an irregular curvature of the cornea that causes distorted vision. It is also measured in diopters (D) and is typically a positive or negative number.
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Axis: This is the angle at which the cylinder correction is oriented, measured in degrees from 0 to 180.
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Add (ADD): This is the additional lens power needed to correct for presbyopia, which is the loss of near vision that occurs as we age. It is typically a positive number and is only included in prescriptions for multifocal lenses, such as progressive lenses or bifocal lenses.
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PD (pupillary distance): This is the distance between the centers of the pupils in the eyes, measured in millimeters. It is important for ensuring that the glasses are properly aligned with the wearer's eyes.
Refractive Error
One other term to be aware of is, refractive error, this is the extent to which a person's eyes are unable to focus light correctly, resulting in blurry vision. The most common types of refractive errors are myopia (nearsightedness), hyperopia (farsightedness), and astigmatism.
Summary
It's important to note that a glasses prescription is not the same as a medical diagnosis. It is simply a tool that helps opticians and other eye care professionals determine the best type and strength of glasses or contacts for correcting a person's vision. If you have been prescribed glasses or contacts, it's important to follow your eye doctor's recommendations and wear them as directed in order to maintain good vision and eye health.
At Enjoy Optical, we do not write prescriptions on site but can recommend our optometrist & ophthalmologist friends nearby. Bring your written prescription to us and we will help you find the perfect pair of frames and latest lens technology.