What do all those numbers on my eyeglass prescription mean?

An eyeglass prescription is written in a standardized format so it can be interpreted worldwide. Let's look at one and see what all the numbers mean: Let's say the eyeglass prescription for your right eye is: -2.00 -1.00 x 180.

The first number (-2.00) indicates the spherical lens power to correct nearsightedness or farsightedness. If the number is preceded by a minus sign (as it is here), this indicates a lens power to correct nearsightedness. If the number were preceded by a plus sign (+), then the lens power would be one to correct farsightedness. In all cases, the unit of power for numbers in an eyeglass prescription is called a diopter (D). So this eyeglass prescription is calling for the correction of 2.00 D of nearsightedness.

The second number (-1.00) is the supplemental lens power (called "cylinder" power) being prescribed for the correction of astigmatism. Cylinder power can be preceded by a minus sign or a plus sign, depending on the prescribing style your eye doctor chooses. If you have no need for astigmatism correction, your doctor might simply draw a horizontal line through this box on your prescription or write "SPH" or "DS" to indicate that only spherical power to correct nearsightedness or farsightedness is needed.

The third number ( x 180) indicates the location of what's called the "axis" of the astigmatism correction. Unlike spherical lens powers that correct nearsightedness or farsightedness, cylinder powers to correct astigmatism have a different amount of power in different meridians of the lens. (Think of meridians like the spokes of a wheel.) The axis of astigmatism is the meridian of the cylinder that has zero power, and it always will be a number between 1 and 180 on your prescription, preceded by an "x." If you have no astigmatism, this part of your eyeglass prescription will be left blank.

If you have presbyopia and need bifocals or other multifocal lenses, your eyeglass prescription will contain a number in a box marked "ADD". This is the additional magnifying power placed in the lower half of your lenses to improve your reading vision. It might be preceded by a "+" sign, and it typically will be a number between 0.75 and 3.00.

Finally, you may see the notations "OD" and "OS" on your eyeglasses prescription. These are abbreviations for Latin terms that mean "right eye" (OD) and "left eye" (OS). Sometimes, you might see a third abbreviation: "OU." This means "both eyes."

https://www.zinff.com

此博客中的热门博文

Have you chosen the right glasses?

With the development of science and technology and the popularity of digital products, more and more people wear glasses for myopia. Previously, people wear glasses only as a way to correct their poor vision. Now glasses are not only used correct myopia, but also as a very important decoration for people. If your glasses are not match with your style, the glasses will have bad influence on your image. How do you match your own glasses with your style? Here's how to choose the right eye for you. 1. Choose according to your face type How to identify your face: Give yourself a face contour and pick up your forehead to reveal the hairline. Take a frontal photo of yourself with a camera or mobile phone, pass it to the computer, use the drawing tools to trace the outline of the face, and the face map is done. Compare the face classification to find out your face shape. Various face types round face suitable for the water chest or rectangula...

阅读全文

How Often should you replace glasses?

Many of us go for years at a time without considering changing out our glasses because we doggedly believe that we can still see perfectly with our old lenses. While you may not have noticed or realized it, your old eyeglasses may be working against you, causing undue eyestrain or fatigue. But how often should we replace our glasses, and why? Listen to the Advice of Your Optometrist Your glasses should be replaced when your optometrist recommends that they should be. This usually will occur in tandem with your regular eye exam. The American Optometric Association recommends that non-senior adults and children over age 6 have regular eye exams a minimum of once every two years if they do not have risk factors for poor vision. Seniors over age 60 and individuals with risk factors should have an eye exam every year, or more frequently if recommended by their doctor. During this regular eye exam, you will need to ask your optometrist whether or not you need to replace your glasses w...

阅读全文

Eyeglass Basics

Modern eyewear serves a dual purpose. In addition to being a vision-correcting medical device used to enhance your safety and quality of life, eyeglasses have become a major fashion accessory. Therefore, when it comes to selecting eyeglasses there are many important factors to consider. The Frame Frames are made from a large variety of materials ranging from acetates and hard plastics to metals and metal alloys. The quality of frame materials is very high nowadays with many cutting-edge manufacturers investing heavily in developing new innovations and materials to make stronger, more flexible, lighter and more beautiful frames. In considering the optimal material for your eyeglass frame, your lifestyle plays a big role. Children and those with active lifestyles require durable and flexible frames that are resistant to breaks from hits and falls. Those who have skin allergies need to seek out frames made from hypoallergenic materials such as acetate, titanium or stainless ste...

阅读全文

zinff

搜索此博客