Can I use my glasses prescription for contact lenses?

ICOICE Colored Contact Lenses Online Jan 15, 2024

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.

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.

Advantages and Disadvantages of wearing contact lenses


  • Contact lenses are specifically designed to conform to the natural curvature of your eyes, ensuring a comfortable fit and providing clear vision.
  • Contacts offer freedom of movement, making them ideal for individuals with highly active lifestyles.
  • Contact lenses provide a discreet option that does not alter your facial features or obstruct your vision.
  • Colored contacts allow you to express your unique style and enhance your appearance.
  • Contacts are not affected by weather conditions such as rain, snow, or humidity.


  • The initial process of inserting and removing contact lenses can be intimidating and uncomfortable, especially for beginners.
  • Contact lenses typically require more care and delicate handling compared to glasses due to their fragile material.
  • Proper cleaning and care are necessary for contacts to reduce the risk of infection, unless you opt for daily-wear lenses.
  • Contact lenses need to be replaced more frequently than eyeglasses, which can result in higher expenses.
  • Some individuals with sensitive eyes may find contact lenses uncomfortable, and they can potentially worsen the symptoms of dry eye syndrome.

Advantages and Disadvantages of wearing eyeglasses


  • Eyeglasses provide convenience as they can be easily removed when necessary.
  • Glasses offer a low-maintenance option for individuals who only require vision correction for specific activities such as reading, driving, or using digital devices.
  • Wearing eyeglasses reduces the risk of infection and irritation by preventing people from touching their eyes.
  • Glasses offer protection for the eyes against debris, dust particles, wind, and various environmental elements.
  • Depending on the lens type (e.g., sunglasses or light-reactive lenses), glasses may offer protection from the sun's ultraviolet rays.
  • Well-maintained glasses can last for years before needing replacement, assuming there are no changes in your prescription.


  • Eyeglasses can be limiting and inconvenient during exercise or when participating in sports.
  • The lenses of eyeglasses can reflect your eyes or objects behind you, potentially causing distractions for others.
  • Fog and precipitation, such as rain or snow, can collect on the lenses of your glasses and obstruct your vision.

Can glasses prescription be used for contact lenses?

When it comes to vision correction, many people wonder if a glasses prescription can be used interchangeably for contact lenses. While both glasses and contact lenses serve the purpose of correcting refractive errors, such as nearsightedness, farsightedness, and astigmatism, there are significant differences between the two. In this article, we will explore the distinctions between a glasses prescription and a contact lens prescription, shedding light on why they are not the same and the importance of obtaining a separate prescription for contact lenses.

Prescription Format:

A glasses prescription is typically written in a format that specifies the lens power required for each eye individually.

In contrast, a contact lens prescription includes additional parameters such as base curve, diameter, and brand, as these factors are crucial in determining the right fit and comfort for the contact lenses.

Eye Physiology:

Contact lenses rest directly on the surface of the eye, requiring a different set of measurements than glasses.

Variables like corneal curvature, tear film, and eye moisture are taken into account when prescribing contact lenses, which are not considered in a glasses prescription.

Vision Correction:

Glasses sit approximately 12 millimeters away from the eyes, while contact lenses are placed directly on the cornea.

Due to these differences in proximity, the lens power required for glasses and contact lenses can vary, leading to a distinct prescription for each.

Importance of a Contact Lens Prescription:

Eye Health and Safety:

The fit of contact lenses is critical for maintaining good eye health and preventing complications.

An eye doctor evaluates the cornea's shape, size, and overall eye health to determine the appropriate contact lens prescription.

Without a proper contact lens prescription, wearing contacts that do not fit properly can lead to discomfort, eye infections, corneal damage, and other complications.

Customization for Comfort:

Contact lenses come in various materials, designs, and sizes to accommodate different eye conditions and individual preferences.

A contact lens prescription ensures that the lenses are tailored to the specific needs of the wearer, providing optimal comfort and visual clarity.

Ongoing Monitoring:

Regular eye exams and contact lens fittings are necessary to ensure the continued health and suitability of contact lenses.

Eye doctors monitor changes in prescription, eye health, and the effectiveness of contact lens wear during these follow-up appointments.


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.