The number of Canadians who need vision correction is rising. In Canada, about 74% of people require eyeglasses, contacts, or laser eye surgery in order to see clearly.
Whether or not you have vision issues, it's imperative to have a yearly eye checkup. Eye exams are even more important if you do have vision issues. Your doctor will update your prescription and examine your eyes generally during an eye exam. You might be curious about how your optometrist decides your prescription if you presently wear glasses or believe you might need them in the future.
Read on to find out everything you need to know about how your eye doctor measures your prescription, how to read your own prescription, and why it's crucial to have your prescription updated.
I NEED A PRESCRIPTION, BUT WHY?
Simply expressed, a prescription is required for eyeglasses and contact lenses because better vision requires a measurable improvement. Your doctor will assess your eyes during an eye exam, and based on the results, they will advise corrective lenses. The numerical value of these corrective lenses will correspond to the curvature that must be corrected in order to correct your vision. This figure represents your prescription.
Typical Vision Issues That Need a Prescription
The most frequent visual issues that need for a prescription are refractive errors. Refractive mistakes consist of:
Hyperopia: A vision ailment known as hyperopia, or farsightedness, makes it easier to perceive distant objects than nearby ones.
Myopia : When you have myopia, also known as nearsightedness, you can see things well up close but they appear fuzzy from a distance.
Astigmatism : it is when the surface of the eye (the cornea and lens) are not spherical and instead are shaped more like an American football. Images may become distorted as a result, both up close and far away.
HOW YOUR VISION IS CORRECTED BY CONTACTS AND GLASSES
A brief grasp of how the eyes function may be beneficial to comprehend how eyeglasses and contact lenses fix your vision. The following are the fundamental steps in vision:
- When you focus on something, initially light enters your eye through the cornea, which has a dome-like shape and bends the light to aid in focusing.
- Your pupil allows light to enter your eye, and the iris regulates how much light is allowed in.
- This light then travels through your eye's lens. Together, the cornea and lens correctly direct light onto the retina, where photoreceptors convert it into electrical signals.
- These electrical signals travel to the optic nerve, where they are processed into the images you see, and then to the brain.
You might have trouble seeing clearly if one of these steps isn't done correctly. Your vision can be improved with a special lens made to fit your needs.
IN WHAT MANNER IS MY PRESCRIPTION MEASURED?
Refraction tests are the main methods used to determine your prescription. Both physical labour and technological methods, such as the use of autorefractors and autokeratometers, are acceptable.
Testing Refraction
Your eye doctor will perform a refraction test to ascertain your precise prescription for eyeglasses.
During a refraction test, your optometrist will employ a device known as a phoropter to assess your vision while using a variety of lenses. Your eye doctor will quiz you on each new lens to determine which one improves your vision.
Your eye doctor will adjust the lens power as you continue to respond to questions to arrive at a final eyeglass prescription.
Autonomous Tests
To automatically calculate your eyeglass prescription, your eye doctor may also employ autorefractors or autokeratometers. Usually, this is utilised as a beginning point. Your optometrist will then use a phoropter to further specify the prescription.
The process of autorefraction is simple and fairly quick. Usually, three measures are obtained, and the average of those three values serves as your prescription. An autorefraction exam typically lasts between 10 and 15 seconds because there are no questions to be answered.
MY PRESCRIPTION: HOW DO I READ IT?
If you require a prescription, you should be aware that your prescription for contacts may differ from your prescription for glasses. This is because eyeglass lenses lay about 12 mm from your eye while contact lenses rest immediately on your eye.
During a routine comprehensive eye exam, your eye doctor will check your prescription for glasses, but if you choose to wear contacts, you might also require a contact lens fitting and exam.