Are Contact Lenses Prescription The Same As Glasses?

When initially comparing contact lens and glasses prescriptions, it may be tempting to assume that they are identical since they both aim to correct vision problems. However, while they share some similarities and address issues like nearsightedness, farsightedness, or astigmatism, they are not interchangeable. The prescriptions are specifically tailored to the chosen method of vision correction.

To address common inquiries from customers regarding their prescriptions, the ICOICE team has compiled informative answers. Let's explore the distinctions between contact lens and glasses prescriptions and determine which solution is most suitable for your needs.

Is a glasses prescription the same as contact lenses?

Contact lens and glasses prescriptions share certain similarities, but they are not identical. Their primary purpose is to address refractive errors that hinder clear vision. What exactly is a refractive error? It refers to vision problems caused by the shape of the eye and its ability to bend light, resulting in blurry vision. Common refractive errors include myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (when the curvature of the eye is asymmetrical). Both contact lenses and glasses have the capability to correct refractive errors and restore visual acuity. However, they achieve this through entirely different mechanisms. Although your contact lens and glasses prescription may look similar, it does not mean they will give you the same visual acuity if you try to convert one to the other.

What are the differences between glasses and contact lens prescriptions?

Glasses and contact lens prescriptions have notable distinctions due to the differing positioning of glasses and contact lenses on the eye. Glasses are positioned about 12 millimeters away from the eye, while contacts sit directly on the surface of the eye. This 12-millimeter difference can have a significant impact and can result in substantial variations in prescriptions between the two.

Furthermore, contact lens prescriptions require additional specifications compared to glasses prescriptions. These specifications include:

Lens Diameter: The lens diameter specifies the size of the lens as measured to fit your eye. Soft contact lenses typically have a diameter range of 13.5 to 14.5 millimeters, while hard contacts range from 8.5 to 9.5 millimeters. These diameters are not universally applicable, which is why a contact lens fitting exam is necessary.

Base Curve: The base curve refers to the curvature of the back surface of the lens and is determined by the shape of your cornea. This curve ensures proper fitting of the lens and helps it stay in place.

Lens Brand: Unlike glasses prescriptions, contact lens prescriptions also include the specific brand of lenses. This is because different brands utilize distinct lens materials, which affect breathability. It is important to consult an eye doctor before switching brands.

Expiration Date: Contact lens prescriptions and glasses prescriptions typically have different expiration dates. It is likely that your contact lens prescription will expire before your glasses prescription, so it is essential to double-check the expiration date.

As evident, there are several differences between these two types of prescriptions. Even slight changes can have a significant impact, underscoring the importance of obtaining an updated prescription from an optometrist before ordering either contact lenses or glasses frames.

What do the abbreviations on prescriptions mean?

We have discussed the additional components of contact lens prescriptions. However, you may come across unfamiliar abbreviations on your prescriptions for contact lenses and glasses. Let's go over the meanings of these abbreviations so that you can have a better understanding of your prescriptions and the differences between them.

• OD or Oculus Dexter: This abbreviation simply refers to the right eye. It is also common to see "RE" used as an alternative.
• OS or Oculus Sinister: This abbreviation is used to denote the left eye. It is also common to see "LE" used instead.
• OU or Oculus Uterque: This abbreviation indicates both eyes.
• SPH or Sphere: The sphere or curve of the lens is measured in diopters and represents the prescription strength. It may also be written as "Power". The further away from zero this number is, the stronger the prescription.
• Minus Sign or (-): This sign indicates nearsightedness.
• Plus Sign or (+): This sign indicates farsightedness.
• CYL or Cylinder: This abbreviation specifies the amount of power required to correct astigmatism.
• Axis: This term specifies the orientation of an astigmatism.
• ADD or Addition: This abbreviation is used for lenses in bifocal and progressive lenses. It indicates the additional correction needed to address farsightedness.
• PD or Pupillary Distance: This refers to the distance between the centers of your pupils.
• BC or Base Curve: This abbreviation specifies the base curve of each contact lens.
• DIA or Diameter: This abbreviation specifies the size of the contact lens.

Is it possible to convert a prescription for glasses into one for contact lenses?

After understanding the distinctions between contact lens and glasses prescriptions, you may be curious about the possibility of converting a glasses prescription into one suitable for contact lenses. The straightforward response to this question is "no." Despite the availability of charts and conversion resources online, obtaining a contact lens prescription necessitates an eye examination and fitting conducted by a licensed eye doctor.

Conclusion:

While a glasses prescription provides the necessary information for vision correction, it is not sufficient for obtaining contact lenses. The unique characteristics of contact lenses require a separate prescription, which takes into account factors such as eye physiology, fit, and individual needs. It is essential to consult with an eye care professional to receive a thorough eye examination and obtain a proper contact lens prescription. By doing so, individuals can enjoy the benefits of comfortable and safe vision correction tailored specifically to their eyes.