Single vision lenses? Easy peasy.
Varifocals? A little more tricky.
“If only I had a less complicated prescription…”
But fret not, because I’ve put together 4 helpful tips which should hopefully make buying varifocals online much much easier. Here's a quick overview.
The key to ordering varifocals online is accurately communicating two vital details; Your ocular centre height and your dual pupillary distance. With these, your resultant lenses are likely to be more accurate, reducing the chances of misalignment.
Ok, but what exactly is your ocular centre and how do you find it? And what is your pupillary distance when it’s at home?
Using the links below, you can;
Learn to measure your ocular height
Advice for buying varifocals online
Finding your optical centres
First up, let’s talk about your optical centres.
In simple terms, this is where your pupils are located, directly behind each of the lenses of your new glasses.
Knowing where your pupils are behind your lenses means they can be aligned to give you the truest and most accurate vision. These positions are measured vertically and horizontally, similar to longitude and latitude.
Your optical centres are the most crucial detail for ordering any kind of glasses online, especially varifocals. This is because progressive lenses are more intricate, containing multifocal lens powers.
Because of this intricacy, varifocal lenses are more sensitive to their positioning over your eyes. Your unique facial structure and how your frame fits you needs to be taken into account to make your lenses as accurate as possible.
In other words, when glasses rest on your nose and ears, their positioning is unique to you.
Oh yea, and different glasses have different sizes of lenses, frame shape and temple thicknesses which all affect how they fit you.
To asses where your optical centres are, you need two measurements.
- Ocular height (OC)
- Pupillary distance (PD)
Measure your Ocular height
Your ocular height (OC or OCH) determines the vertical height between your pupil and lowermost part of your lens.
In order to find your OC height, the best method is to have the glasses on your face. Yep, you need to try them on before ordering your lenses.
We recommend marking where your pupils are on the demonstration lenses (demos) fitted in your new glasses frame. Here’s how;
With help
- Stand/sit in front of your assistant
- Wear the glasses you’re ordering lenses for
- Your assistant vertically holds a plastic ruler against one of your lenses
- They align the 0mm mark with your pupil centre
- They assess the distance to the bottom of your lens
- They note each height according to your left and right, not theirs
On your own
- Stand/sit in front of a mirror
- Wear the glasses you’re ordering lenses for
- Vertically hold a plastic ruler against one of your lenses
- Align the 0mm mark with your pupil centre
- Assess the distance to the bottom of your lens
- Note each height for each of your eyes
OC height tips
- Only measure the lens, not the frame
- Use a plastic ruler to prevent scratches
- If it helps, close one of your eyes to help you see the ruler
- Brace the ruler on the side of your nose and the frame/lens
- Your measurements are for your perspective of left and right, not your assistants.
We use this method to make your lenses as accurate as possible. For the extra time, this method will prevent any vertical misalignment of your pupils behind your lenses.
According to a recent article by “Which?” many online retailers rarely consider ocular centres for their varifocal customers.
“If you’re buying varifocals, it’s vitally important to position the pupils not just horizontally but vertically in the lenses.
This is rarely done online and is not addressed in optician regulations, but we think this needs to change.”
Extract from an article by Which?
Unsure how varifocals actually work?
Check out this article which explains the workings of progressive lenses.
Measure your Dual Pupillary Distances
This refers to the horizontal position of your pupils behind your lenses.
Dual PD accounts for the distance from the centre of your nose to the centre of each of your pupils in each eye. As a varifocal wearer, it’s vital you measure both PD's for both eyes.
The trouble is, your dual pupillary distances might be missing from your prescription paper. Which is super annoying, because it’s vital for ordering varifocal glasses online.
You’d think opticians did it on purpose or something…
No big deal though, you can measure it yourself with our free printable PD ruler below.
Printed to scale, it’s got a slot for your nose and a mirror-friendly ruler for each of your eyes. The slot mimics how your glasses rest on your face and also keeps the ruler steady as your read your measurement.
Is your Dual PD missing from your prescription?
Give this PD ruler a go.
Download this free PD ruler.
Choose the right varifocal lenses
In case you didn't know, there are three main vision "zones."
- Close = within 35cm from your face
- Intermediate = Within arm’s length
- Distance = anything beyond arm’s length
Depending on what you use your glasses for, varifocal lenses can assist you with any or all three of these vision zones.
Based on your glasses purpose, your can choose from two main types of varifocal lens described as Everyday Varifocals or Occupational Varifocals.
Which type suits you best?
Everyday varifocals offer the maximum range of multifocal power.
For everyday tasks such as reading, watching television or driving, everyday varifocals assist you with near, intermediate and distance vision.
From the top to the bottom of the lens, they contain all three corrective powers and have the largest focal range from close to far away.
Because of this, the visual progression between the “focal zones” with these lenses are more sensitive and can take a little practice to get used to.
Occupational varifocals are for near to intermediate multifocal power.
In your place of work, your environment requires you to see less extreme distances.
As such, the range of focal power in occupational varifocals is tuned for shorter distances between near and intermediate, usually limited to a maximum distance of 4m.
Office lenses give you a much larger intermediate lens-section to help you focus on near and intermediate tasks such as typing, looking at your computer and writing.
This is handy for reading a nearby office notice board but is certainly unsuitable for distance tasks such as driving.
Your prescription
One last tip.
Before you order your new varifocals, it’s worth mentioning your prescription details.
In order to get the most out of your new glasses, you should try to implement an up to date prescription from at least within the last 12 months.
Reason being?
As a varifocal wearer, your eyes are more likely to change since your last eye examination. Varifocal wearers usually undertake more frequent optical analysis at least once every year so it’s important to keep that in mind if you’re buying varifocal glasses.
Conclusion: Can I buy varifocal glasses online?
You can order your varifocal glasses following the steps above.
- Using your free PD ruler, you can accurately communicate the horizontal positioning of your pupils behind your new spectacle lenses.
- Using a marker pen, you can indicate the vertical positioning (OC) of your pupils behind your your new spectacle lenses.
Combined with a recent prescription paper, these simple steps can alleviate the chances of poorly aligned lenses, eye strain or dysfunctional new glasses you don't enjoy wearing.
Hopefully, you’ve found this article useful and you feel more comfortable knowing what to do when ordering your new pair of varifocal glasses.
If you have any questions about the topics written in this article, please feel free to get in touch with me here.
Thanks for reading.
