What is Pupillary Distance?
Pupillary distance (PD) is the measurement, in millimeters, between the centers of the pupils of the eyes. It is an important measurement that is used in the manufacture of eyeglasses and contact lenses. If you wear eyeglasses, it is essential to know your pupillary distance to ensure that your prescription lenses are correctly positioned in the frames. In this blog, we will discuss what pupillary distance is, how it is measured, and why it is important to know your PD when ordering eyeglass frames online.
How is Pupillary Distance Measured?
Pupillary distance can be measured in several ways. One of the most common methods is to use a pupillometer, which is a handheld device that measures the distance between the centers of the pupils. Another method is to use a ruler or a tape measure to measure the distance between the centers of the pupils. This method is not as accurate as using a pupillometer, but it can be useful in a pinch.
Why is it Important to Know Your Pupillary Distance?
Knowing your pupillary distance is important because it ensures that the optical centers of the lenses in your eyeglasses are correctly positioned. If the optical centers are not aligned with your pupils, you may experience eye strain, headaches, or even double vision. This is particularly important if you have a strong prescription or if you have astigmatism. When ordering eyeglasses online, it is essential to know your pupillary distance. This is because you will need to provide this measurement to the online retailer to ensure that your glasses are made correctly. If you do not know your pupillary distance, you may not be able to order glasses online or may receive glasses that are not correctly aligned with your pupils.
How to Measure Your Pupillary Distance?
There are several ways to measure your pupillary distance. One way is to visit an optometrist or an ophthalmologist, who can measure your PD for you. Another way is to use a mirror and a ruler or a tape measure to measure the distance between the centers of your pupils. Here's how to do it:
Stand about arms-length away from a mirror in a well-lit room.
Hold a ruler or a tape measure against your forehead, making sure that the zero mark is aligned with the center of one of your pupils.
Look straight ahead and close one eye.
Read the measurement at the center of the other pupil.
Repeat the process with the other eye.
The two measurements should be added together to get your total PD.
It's important to note that measuring your pupillary distance at home may not be as accurate as having it measured by an eye care professional. If you have any doubts about the accuracy of your measurement, it's always best to visit an optometrist or an ophthalmologist to have your PD measured.
It's important to note that your pupillary distance can vary depending on whether you are looking at something up close or far away. This is called your near PD and your distance PD. When ordering eyeglasses online, it's important to provide both measurements to ensure that your glasses are made correctly.
In addition to eyeglasses, pupillary distance is also important for those who wear contact lenses. This is because the size and shape of the contact lens must be matched to the size and shape of the cornea, which is located near the pupil. Knowing your pupillary distance can help your eye care professional determine the correct size and shape of the contact lens.
In summary, pupillary distance is an important measurement that should not be overlooked when ordering eyeglasses or contact lenses. By knowing your pupillary distance, you can ensure that your glasses or contact lenses are correctly aligned with your pupils, which can help prevent eye strain, headaches, and other vision problems. If you're not sure what your pupillary distance is, be sure to visit an eye care professional to have it measured.
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