How to Read Contact Prescription – Overview
According to renowned lens experts, reading contact prescriptions is difficult for individuals. The numbers and other things mentioned in the prescription are written in an alien language that needs proper understanding. If you have been completed your contact lens fitting and wondering how to read the contact prescription, this guide will help you do so.
The Basics of Contact Prescription
The Contact Prescription is entirely different from the prescription that your optician prescribes for glasses. A contact prescription comes in different parts, and each part contains unique information. You need to understand each section to read the contact prescription yourself. Let’s decode each part of the prescription.
1. Base Curve (BC)
The required fit type your eyes require for the lens is described in this part. The base curve measurement is prescribed in millimeters. It is also prescribed as flat, median, or steep.
2. Power/ Sphere (PWR/ SPH/ D)
This information indicates the type of vision you need i.e. farsighted or nearsighted. It also explains how much correction your eyes require for the right vision.
3. Diameter (DIA)
The diameter determines the width of the lens. This information is written in millimeters.
4. Cylinder (CYL)
The cylinder part includes the value for the cylinder and axis if you require a toric lens.
5. Axis (AX)
The axis information determines the correct angle needed to get the right vision.
6. Addition (ADD)
Additional information is prescribed for those suffering from presbyopia. This information determines the amount of correction a person needs to see things.
Dominant value is there for those who wear bifocal lenses or multifocal lenses. A Dominant value is there to correct the vision for the dominant and nondominant eye.
What Do the Numbers Mean in Contact Prescription?
The contact prescription codes mentioned above are there to understand what types of things a person requires to get the right vision. Besides codes, the contact prescription also features numbers. What do the numbers mean in contact prescription? Let’s find out!
1. Power Prescription Number
The power prescription number describes the grade of correction your eyes need for perfect vision. The power prescription number is measured in increments of 0.25 diopters. If the number is away from zero, the user needs more vision correction.
2. Cylinder Prescription Number
A cylinder prescription number is measured in increments of 0.25. The number is always negative. It signifies the amount of astigmatism.
3. The Axis Figure
An axis figure is a number from 0 to 180 degrees. It describes the angle of correction needed for the best vision.
4. Additional Figure
It is a positive number between 0.50 to 3.00 for those with presbyopia. Contact lens brands prescribe the figure as high, low, or medium.
What’s the Need for a Contact Prescription?
It is illegal to sell contact lenses without a doctor’s prescription. You can’t buy a pair of lenses without a prescription in the United States.
Contact Lenses are considered medical devices. For that reason, it needs a contact prescription from the eye specialist.
If you buy contacts without a prescription, it might cause loss of vision or other eye-related problems. Your eyes might get inflammation or infection due to unfit contact lenses. Some companies use different materials that make it uncomfortable for the users to wear. As a result, you have to face many problems in the future.
Does the Contact Prescription Come with an Expiry?
Yes, a contact prescription comes with an expiry. As per the government’s rule, a contact prescription lasts for a year. If you buy a pair of lenses with a year-old prescription, it will be invalid. You’ll have to go to an eye specialist or optician to get a new contact prescription, as it has expired already.
Some states in the US accept extended prescriptions. You need to collect the correct information about the expiry date of the contact prescription before you use it to buy a new pair of lenses for your eyes.
Once your contact prescription is expired, you need to visit the eye specialist again, get your eyes checked, and then the doctor will prescribe you a new contact prescription with updated information. The upgraded prescription will help you get new lenses. Remember, the validity for the upgraded prescription is also one year.
The Bottom Line:
Now you know how you can read contact prescriptions. There are many other parameters that you need to understand to read the contact prescription correctly. However, the further information is for the doctor’s side and not for the user’s side. You can follow the codes and information provided in the above article to best understand the contact prescription.