In the previous article, we discussed “Contact lenses or glasses, which is better?”. In this article, let’s talk about “Is the prescription for glasses the same as for contact lenses?”.
Is the prescription for glasses the same as for contact lenses?
A prescription for contact lenses is not the same as a prescription for regular glasses. The two types of glasses are quite different because glasses are located about 12mm from the eye, while contact lenses are located directly on the surface of the eye. If you want to wear both contact lenses and regular glasses, you'll need two different prescriptions. Contact lenses are worn in the eyes, and the frame is at a distance from the eye, although the distance is not large, definitely can affect certain degrees.
Can I use my prescription for contact lenses?
You cannot and should not use your glasses prescription to calculate your contact lens prescription. It's important to note that not everyone who needs glasses can wear contact lenses, and it's important to check them separately. Some people have sensitive corneas or other eye complications and never get used to wearing contact lenses.
Why is a prescription for glasses different from a prescription for contact lenses?
The frame glasses degrees are the optometric degrees of the eye, and the difference between the frame glasses degrees and the contact lens degrees is mainly due to the different contact distances between the two lenses and the eye. Usually, degrees of contact lenses and glasses need to be converted by a professional through vertex diopter. The conversion formula is Fc=Fs/(1-d×Fs). In the formula, Fc is the diopter of contact lens, Fs is the diopter of glasses frame lens, and D is the distance between frame glasses lens and cornea. Assuming that the prescription of frame glasses is -4.00d and the distance between lens apex is 12mm, the prescription of contact lenses is -4.00/ [1-0.012×(-4.00)] = -3.82d.
Can I get a prescription for contact lenses?
Once a contact lens prescription is established, you are entitled to a copy. In some cases, this may occur after a diagnostic match. In many typical GP lenses and special designs, such as bifocal, annular, keratoconus, or postoperative, it may take several examinations before a successful match can be made and a prescription can be provided. If contact lenses are not issued by a doctor, it is important that whoever dispenses them is completely accurate. A soft lens Rx usually includes lens material name, design, power, base curve, and diameter. GP lens prescriptions usually have this information and more, like perimeter curve radius, center thickness, special perimeter design, and optical area diameter.
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