Glasses Prescription to a Contact Lens Prescription?

Glasses and contact lenses help correct myopia, hyperopia, and astigmatism. But before you get corrective lenses, you need a prescription from an eye doctor. To determine the prescription, the doctor will need to carry out a vision test to find the power needed to correct sight.

Glasses and contact lens prescriptions may serve the same purposes, but they are not the same. Here is information on whether you can convert a glass prescription to a contact lens prescription.

Eyeglass Prescriptions

The power of the lenses will depend on the distance between the eye and the corrective lens, also called the vertex distance. Eyeglasses prescriptions indicate:

The lens power.
The strength of astigmatism.
The cylinder orientation.

If you require multifocal lenses, the prescription will also indicate the additional power.

Contact Lens Prescriptions

Contact lens prescriptions contain details such as:

Base curve measurement.
Lens diameter.
Lens material.
Brand or manufacturer.

The base curve is determined by the patient’s eye shape, and it is crucial for getting the right lens fit. The lens diameter, in this case, is the overall size of the contact lens. The lens material or type is vital for ensuring that you get the best correction.

Glasses Prescriptions vs. Contact Lens Prescriptions

Glasses sit some distance from the eyes, while contacts rest on the eye, meaning the prescription will not be the same. The tests and measurements are different, so substituting one prescription for the other will not give you similar visual acuity.

The information that goes into prescriptions will include the refractive error, the lens strength, and the type of lens needed. Glass prescriptions indicate a value for cylinder and axis, which does not exist for contacts.

Converting Prescriptions

To switch from glasses to contact lenses, you cannot directly convert your glasses prescription. Also, trying to calculate your lens prescription yourself is a huge mistake.

Not everyone who wears glasses can wear contacts. You need a separate eye exam before making the switch. Some people have corneal and eye complications that make it difficult to wear contacts, leading to great discomfort.

Ordering Glasses or Contacts Online

While it is possible to order lenses online, you still need a valid prescription. There are online sites that provide conversion charts to convert prescriptions. The vertex conversion charts are readily available for use, though the best people to use them are eye professionals.

A lot more goes into contact lens prescriptions than power. The calculations can help, but you should not use the information to order lenses online.

Many eye specialists agree that trying to convert prescriptions from glasses to contacts using calculations may not yield accurate results. A contact lens exam will involve tests that go beyond the lens strength. It is necessary to visit an eye specialist for complete testing. The shape and size of the contact lens will affect its function.

For more on converting a glasses prescription to a contact lens prescription, call Parkside Eye Care at (919) 883-9987 to reach our office in Cary, North Carolina.