Does Pupillary Distance Matter With Single Vision Glasses?

Many patients ask, “Does pupillary distance matter with single vision glasses?” It is a good question because it does not always matter. Let’s take a look when measurement of the distance between the two centers of your pupils makes a difference in your new glasses.

When Does Pupillary Distance Matter With Single Vision Glasses?

In single vision eyewear, the lenses have the same prescription power throughout the entire lens, making accurate PD measurement important to ensure clear vision. An incorrect PD can cause visual discomfort, eye strain, and potentially inaccurate correction of the refractive error.

The pupillary distance, also called PD, of a person matters more in some cases and less in other. Before we dive into when pupillary distance matters, let’s understand pupillary distance and how it relates to your glasses prescription.

What Is Pupillary Distance?

Pupillary distance (PD) refers to the measurement of the distance between the centers of the pupils in each eye. It is typically expressed in millimeters (mm). The PD is an essential measurement used in the process of fitting prescription eyeglasses or contact lenses.

The accurate determination of pupillary distance is important because it ensures that the optical centers of the lenses align with the center of each eye. Proper alignment is crucial for optimal vision correction, as it helps to ensure that the eyewear provides clear and comfortable vision. 

The best vision is achieved when the optical center of the lens in the eyeglasses aligns with the center of your pupils. Here are some things that can factor into how errors in pupillary distance can lead to blurry vision in single vision lenses.

1. High Hyperopes, High Myopes, High Astigmatism

In patients who are high hyperopes, high myopes or those patients that have very high astigmatism, having the correct PD value will matter more. 

What Is A High Hyperope?

A high hyperope refers to an individual who has a significant degree of hyperopia, also known as farsightedness. Hyperopia is a refractive error in which distant objects are seen more clearly than nearby objects. In high hyperopia, the degree of farsightedness is relatively high, indicating a greater refractive error.

For example, someone with a prescription of +1.00 is a hyperope but not a high hyperope. However, someone with a prescription of +6.00 would be considered a high hyperope. The strong the power of your prescription lenses, the more the pupillary distance will matter.

What Is A High Myope?

A high myope refers to an individual who has a significant degree of myopia, also known as nearsightedness. Myopia is a refractive error in which distant objects appear blurry, while close-up objects can be seen more clearly. In the case of a high myope, the degree of nearsightedness is relatively high, indicating a greater refractive error.

A regular myope may have a prescription of -1 in each eye. A high myope may have a prescription of -7.00 in each eye. Similar to the degree of hyperopia, higher degrees of myopia are more affected if you have measured the wrong PD.

What Does A Single Vision Astigmatic Correction Look Like?

What if you only have an astigmatic correction in your new pair of glasses? An example of a single vision correction for high astigmatism could be a pair of prescription eyeglasses or contact lenses specifically designed to address astigmatism. The correction for high astigmatism would involve a prescription that corrects the irregular curvature of the cornea or lens of the eye, which causes the distorted or blurry vision associated with astigmatism.

For instance, an example prescription for high astigmatism correction might look like this:

OD (right eye):

• Sphere: plano(no nearsightedness or farsightedness correction)
• Cylinder: -4.50 (for astigmatism)
• Axis: 90 degrees (the orientation of the astigmatism correction)

OS (left eye):

• Sphere: plano (no nearsightedness or farsightedness correction)
• Cylinder: -4.75 (for astigmatism)
• Axis: 180 degrees (the orientation of the astigmatism correction)

Because the astigmatism already must be located on the correct axis, it is equally important to have the right PD value to ensure that there is no distortion.

2. Wider Or Narrower Face Structures

The average eyeglass prescription accounts for the average adult’s PD. This means if you have a narrower PD than most or you have a wider pupillary distance, you could be more subject to a pair of prescription glasses not fitting you well. 

Average Pupillary Distance For Men

The average adult pupillary distance (PD) for men is typically around 63 to 64 millimeters (mm). However, it’s important to note that pupillary distance can vary among individuals. Some men may have a slightly wider or narrower PD within the normal range.

Average Pupillary Distance For Women

The average adult pupillary distance (PD) for women is typically around 61 to 62 millimeters (mm). However, it’s important to note that pupillary distance can vary among individuals. Some women may have a slightly wider or narrower PD within the normal range.

What Is The Average PD In Children?

The average pupillary distance (PD) for children can vary based on their age and stage of development. Here are some general ranges for average PD measurements in children:

• Infants (0-6 months): The average PD for infants is approximately 41-45 millimeters (mm).
• Toddlers (1-3 years): The average PD for toddlers is typically around 44-48 mm.
• Preschoolers (3-5 years): The average PD for preschoolers is generally between 47-51 mm.
• School-aged children (6-13 years): The average PD for school-aged children tends to range from 51-54 mm.

It’s important to remember that these measurements are approximate averages and can vary among children. 

In the case of kids, adjusting PD for single vision glasses is especially important. Children’s faces are still growing, and their PD may change more rapidly than in adults. Ensuring the correct PD in their glasses may positively impact myopia progression, enabling clearer vision for a longer period. 

For precise measurements, it is recommended to have a child’s pupillary distance measured by an eye care professional during an eye examination. 

Monocular PD Vs Binocular PD

It’s worth noting that there are two types of PD measurements. The Binocular Pupillary Distance is the distance between the pupils when looking straight ahead. The Monocular pupillary distance is the distance between each pupil and the bridge of the nose.

Binocular PD is more commonly used, but in some cases, Monocular PD may be required for certain types of eyewear or prescriptions.

The sum of the monocular PDs of the right and left eye may not always be equal to the binocular PD. This is because the bridge of the nose is not always centered between the eyes, and there may be slight differences in the position of each eye’s pupil relative to the nose.

During an eyewear fitting, an eye care professional (usually an optician) will determine the appropriate pupillary distance measurements based on factors such as the type of eyewear, prescription requirements, and the individual’s facial features. They will consider both the binocular PD and, if necessary, the monocular PD to ensure proper alignment and optimal vision correction for the specific eyewear being fitted.

How Can You Measure PD?

One size does not fit all when it comes to pupillary distance. Each person has a unique PD due to differences in head and face shape. Therefore, when ordering single vision glasses, it is crucial for the wearer to obtain an accurate PD measurement. 

Pupillary distance measurements can be done using a millimeter ruler, PD measuring tool (pupillometer), or a digital ruler on a smartphone.  It is worth noting that while self-measuring can provide a reasonable estimation, the most accurate measurement will always come from a professional.

Symptoms Of Inaccurate PD Values

Pupillary distance (PD) is an essential measurement when ordering prescription glasses, including single vision glasses. It refers to the distance between the centers of the two pupils, which ensures that the optical center of the lenses aligns correctly with the wearer’s pupils. This alignment is crucial for accurate and comfortable vision correction.

Inaccurate pupillary distance measurements can lead to several issues such as blurred vision, eyestrain, headaches, and overall discomfort while wearing the glasses. Therefore, it is essential to have an accurate PD measurement to ensure the best possible visual experience with single vision glasses.

Does Pupillary Distance Matter With Single Vision Glasses: Conclusion

Pupillary distance is an essential measurement when ordering single vision glasses, as it helps align the optical center of the lenses with the wearer’s pupils. This ensures accurate, comfortable, and effective vision correction. If the pupillary distance is inaccurately measured, it may lead to uncomfortable vision or even eyestrain as the eyes struggle to adjust to the misaligned lenses. 

For single vision glasses, having an accurate PD matters the most when a patient has either high myopia, high hyperopia or a high degree of astigmatism. For patients with very low degrees of hyperopia and myopia, and if they have average face structures, this precise accuracy of this measurement matters less.

There are tools available to measure your own pupillary distance. In most cases the most accurate pupillary distance measurement is done by an eye care professional.

Frequently Asked Questions

What happens when the PD measurement is incorrect?

When the pupillary distance (PD) measurement is incorrect, it can lead to eyestrain, headaches, and visual distortion. An incorrect PD may cause the wearer to experience double vision, difficulty focusing, and overall discomfort. It is crucial to have an accurate PD measurement to ensure the optimal visual performance and comfort of the single vision glasses.

Is there a difference in PD for single vision and progressive lenses?

Yes, there can be a difference in PD measurements for single vision and progressive lenses. Progressive lenses may require additional measurements like distance vision, near vision, and intermediate vision in order to provide a seamless transition between the different focal points. However, single vision glasses only require one PD measurement since they usually have only one focal point.

How crucial is precise PD measurement for single vision glasses?

Precise PD measurement is critical for single vision glasses to provide optimal visual performance and comfort. A correct PD ensures that the optical center of each lens aligns with the wearer’s pupils, which is important for accurate and comfortable vision. Incorrect PD measurements can lead to issues such as eyestrain, double vision, and difficulty focusing.

What can happen if the PD is off by a few millimeters?

A PD being off by a few millimeters is usually a lot. Even for low grade prescritpions, it can still cause visual discomfort and distortion. For individuals with higher prescriptions as mentioned above, this visual discomfort will be more pronounced. 

Are there any tools or apps available for calculating your own PD?

Yes, there are various tools and apps available for calculating your own PD. Some online retailers offer PD measuring tools, and there are also smartphone apps that can help measure your PD. It’s crucial to follow the instructions carefully and double-check the accuracy when using these tools. However, a PD measured by a professional optician is typically the most accurate and reliable sources for this measurement.

Do factors like age and gender affect the average pupillary distance?

Factors such as age and gender can affect the average pupillary distance. Generally, the average PD for adult males is larger than that for adult females, approximately 64mm and 61mm, respectively. As for children, their PD tends to be smaller than that of adults. As individuals grow and develop, their PD may change, making it essential to have an accurate and up-to-date measurement for optimal visual performance.