Does Pupillary Distance Matter with Single Vision?
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Yes, pupillary distance does matter when you’re getting single vision glasses. Here we explain why. But first, it’s important to understand single vision, pupillary distance, and the relationship between the two.
What is single vision?
If both your eyes are short sighted, or long sighted, then you will need single vision glasses. So really single vision glasses are exactly what the name suggests – they correct a single eyesight problem.
Single vision glasses differ to progressive lenses, where one lens can be used to correct a number of different eyesight issues.
What is pupillary distance?
If you need glasses, your optometrist will measure your pupillary distance.
Pupillary distance is the distance between the centre of one eye pupil to the centre of the other. Pupillary distance is measured in millimetres, and is sometimes expressed as ‘PD’ on your prescription.
Your pupillary distance can change during childhood and adolescence, but will almost certainly remain the same once you reach adulthood.
The average pupillary distance for adults is between 50 and 70mm.
Why does pupillary distance matter with single vision glasses?
Pupillary distance is extremely important when fitting any kind of glasses – including single vision glasses.
Because all lenses have an optical centre, and this is intended to align precisely with your pupil. Glasses lenses are designed that way for maximum effect.
If the measurement is not correct, this optical centre will still be at the centre of the lens, but it won’t align with your pupil. Instead you’ll be looking through a different part of the lens, which will throw just about everything off kilter!
This can affect your ability to focus correctly, in turn leading to headaches, tired eyes, blurred or double vision, dizziness and nausea.
Is there any room for error?
It’s best to get an accurate reading for pupillary distance, as this will allow your glasses to perform as they should.
However, if you have a prescription for low myopia (meaning you’re only slightly short-sighted) and you do not have an astigmatism, it will have very little impact if your pupillary distance reading is a couple of millimetres out.
The higher the prescription, the more important it is for the pupillary distance measurement to be precise. If you have a very high myopia prescription and the measurement is incorrect, it will quickly lead to headaches and poor vision.
Can I measure my own pupillary distance?
You can try to measure pupillary distance yourself but it’s unlikely to be accurate. As discussed above, even just a miscalculation by a couple of millimetres can really affect the usefulness of your glasses.
Therefore you must be wary of this when buying over the counter glasses, as they will not be fitted to accommodate your pupillary distance. To avoid this,
ask an optometrist to take the measurement for you.
What kind of glasses do I need?
An optometrist will also be able to recommend what kind of lenses you need.
This will depend entirely on the results of an eye exam. If you are short-sighted in one eye or both eyes, you will need single vision glasses. The same goes if you are long-sighted in one or both eyes.
When you use your single vision glasses, you should be able to see effectively, regardless of the distance of the object you are looking at, or the angle of your glasses.
But if you have differing eyesight issues, single vision glasses won’t serve your purpose. For example, if you are short-sighted but also have trouble reading due to presbyopia, you will need bifocals. This enables the upper half of the lens to correct one problem, and the lower half of the lens to correct the other.
Bifocals are a type of progressive lens, as are multifocals, which can also correct different eyesight issues through one lens.
Let us help !
At Image Optometry we offer comprehensive eye exams at affordable prices. We have 19 stores located across British Columbia, Canada, making us the largest, most affordable eye care chain in the province.
We will suggest whether you would benefit from prescription lenses, and if so will recommend the type of lenses you need. Your prescription will include an exact measurement of your pupillary distance.
Having an expert do this for you will ensure optimum function of your glasses, helping to prevent any unwanted side effects such as headaches, blurry vision and nausea.