The Pitfalls of Online Glasses: The Review

cropped-img_9676.jpgAs Always, this is entirely the work of myself, Ric Peralta, The Optical Jedi.

Over the past several years there has been an explosion of online eyeglass ordering options.  I have helped many patients over these who have purchased their glasses online and had issues of one type or another.  In almost every case I have been able to diagnose the problem, and it almost always came down to something the average patient would have no clue about (i.e. progressive design, material type, lens mounting issues, etc.).  Thankfully, as a reader of my blog, you’re definitely not the average patient.

I decided to take it upon myself to explore just how good these lenses can be (or not as the case may be) by ordering a pair for myself to wear and try with my prescription.  What follows is my breakdown of the good…and the bad of that experiment.

Why Some Choose Online Glasses

Listen, I get it.  The marketing angle of the online systems sure sell a sweet deal.  They’ll send you several to try on, or they argue that glasses are overpriced and they have a great deal by cutting out the middleman (i.e. the Doctor’s office).  And for the average consumer, it’s easy to believe the hype.  Of course it feels like glasses cost too much.  After all, isn’t it just a simple piece of plastic for the lens and it can’t be that expensive to make frames, right?  Of course, as I’ve explained in many of my posts on lens and frame technologies, you understand that there is a vast amount of rather expensive technology that has gone into making glasses work much better today than they did in the past.  But even with that knowledge, it’s easy to believe that online ordering can give you a better price on a better product.  After all, that happens for all your tech gadgets, digital downloads of movies, music, and books, why not glasses too?

Potential Pitfalls of Online Glasses

There are many ways things can go very wrong with online ordering.  Whether you are wearing Single Vision or Progressives, there are key measurements of how a frame sits on you which are critical to accurate correction from your glasses.  I have discussed much of this in previous articles, but I will take some time to review here for my new readers.

Pupillary Distance

The distance between your eyes is critical to proper vision through prescription eyewear.  This measurement is called pupillary distance (PD).  It can be measured either as a total distance between both eyes, or measured from your nose to each eye.  If your prescription is relatively simple (that is to say, Single Vision, and not too strong), the single measurement of both eyes together can be fine.  However, if your prescription is strong, or you are wearing a progressive lens, then having the monocular measurement (from bridge to eye) is critical. In addition, this measurement is DIFFERENT for near versus distance vision.  Yes, you read that right!  Your eyes are further apart when looking far away, and closer together when focusing up close.  This is called convergence.  You can even play with this.  If you take a picture of yourself focusing on your finger right in front of you, you will see your pupils are closer together, as they rotate to see the near image.


Monocular PD can very dramatically if it is not measured straight on.

In addition, a prescription lens has an optical center at which power is most correct.  If your eyes do not sit directly in front of that optical center, then there can be an induced correction for eye turn called prism.  This will create eye strain, since it will be pulling your eyes in different directions and can create double vision.

When you are seen by an eyecare professional and a final frame has been chosen, and properly adjusted, then the proper segment height and PD measurements can be taken to ensure your vision is as good as possible once the prescription lenses are put into the frame.  When purchasing from an online retailer, they use a digital version of the frame placed on a photo you upload to approximate the proper fit.  In theory this could work great to get proper measurements, but if you have your head turned only slightly to the right or the left when taking your selfie, or if the camera is closer or further than they anticipate, the computer algorithm will inaccurately guess your measurements.  If your head is turned even slightly to one side or the other it will slide keep your binocular (eye to eye) PD measurement the same, but your monocular (eye to bridge) measurement will change.  For example, with my personal measurements, my real normal monocular PD is 30.5 mm for my right eye, and 30.5 mm for my left eye.  That means my binocular PD is 61 mm.  but if I turn my head over slightly to the right, then my left measurement gets longer and my right gets shorter.  For example, it could become 29.5/31.5  This total is still 61 but now my eyes are being pulled to the side, or in the case of a progressive lens neither eye is in the right place for the reading powers to be clear and sharp.


Estimating PD and Segment Height from a digital approximation is dangerously inaccurate

Segment Height

In addition, if you are wearing a progressive lens, vertical placement of your eyes within the frame is absolutely critical to how your eyes will see, both in distance and near vision.  Since there is a channel through which your eyes flow in a progressive lens, if that channel does not sit directly in line with your eye placement, then you can have wildly distorted vision, or just a mild loss of clarity as you move from distance to near vision and vice versa.

When a digital photograph approximation is done, rather than an accurate in person measurement, there is a VERY high likelihood that the height will be measured inaccurately.  For example if they guess where the frame will sit on your nose, but that does not match what is comfortable for you, it can shift the Seg. Height measurement by as much as 5 mm which could lead to you looking through the computer distance when you are trying to see distance, or lead to your reading zone being so low you can’t see up close without hurting your neck.

On to the Review

Disclaimer:  I will not be disclosing the brand or source of my online purchase.  This is not about singling out any one vendor, but rather to address the online solution as a whole.

From top to bottom, here is the reivew of my experience with online glasses.  The ordering process was incredibly easy.  From looking at potential frames to match my style, to selecting lens features (i.e. progressive, photochromic, anti-reflective coatings).  I had a couple of major concerns that crept up once I made my final frame choice and started to actually create the order.  As someone who works in the eyecare industry, and have done so for almost 30 years, I know that eyeglass prescriptions expire every two years (and in some cases in a single year, depending on State in the US).  And even more importantly I know why this is the case.  This is not about eye doctors trying to squeeze money out of patients, or forcing people to get glasses from us every year, even if their prescription hasn’t changed.  This is entirely driven by health concerns.  There are many major health issues which are spotted by your optometrist or ophthalmologist before they are spotted by your primary care physician.  The smallest visible blood vessels in the entire body are in the retina.  This means we can spot many diseases which manifest in blood flow before anyone else can.  I have spoken about this in my earlier post on retinal imaging. In addition, while a prescription may be “fine” as you see it, changes in prescription can be a bit like that frog in a pot of water.  Slow, incremental changes aren’t necessarily noticed until we correct it.  You could be way off of 20/20 and not even be aware, depending on how long since your last exam.  This particular online ordering system asked for ZERO confirmation or validation of the prescription.  I just typed it in.  This was a giant red flag to me, as an optician.

Then we get to my previous talk on PD and Seg Height.  It didn’t ask for these numbers from me.  It used my photo for all of its measurements.  This was also a big red flag for me..and as I found out later, a warranted red flag.

This particular company had more than one progressive available.  I could just “standard” or “premium.”  I didn’t expect a detailed description of how they differed, but knowing that there are 3000 lens designs, this could mean almost anything.  I opted for the premium just to give this company the best chance at surprising me with quality product.

It took just about a week and a half to receive the glasses, pretty much the same as if they were ordered through a private practice.  They arrived at my home, and I immediately put them on after unwrapping them.  My first reaction was that things were VERY clear and comfortable.  This honestly surprised me, given my previous experience on the other side of these kinds of glasses…

But then I tried to move around.  I immediately felt like I was inside a fish bowl, and the whole world was curving around me.  As long as I didn’t move my head around things were OK, but if I moved side to side I was a goldfish.  I know as much as the next skilled optician that sometimes new progressive designs take time to get used to, even if the prescription is the same.  I didn’t want this to be the place my review ended.  I took them off and switched back to my old pair.  I wanted to start fresh with no “baggage” of looking through a different lens first.  So I waited until the next day…

The next day when I put them on, it was a similar experience.  But I stuck with it, knowing sometimes your brain needs time to adapt.  I became less conscious of the fish bowl but I also noticed I started to develop a nagging headache right in the middle of my forehead.  Things seemed clear but I also felt like I was fighting the glasses somehow.  I had to wait until I got to the lab to analyze what exactly the problem was…

Analyzing the Glasses

This is where my symptoms started to get defined with causes.  As I studied the glasses, making sure about prescription and fit my initial fears about PD and Seg Height became justified.


We use this tool to make sure lenses are level and straight in the frame. As you can see here, the dots at the nose are 2 mm lower than those at the temple.

The first step in checking them was verifying the lenses were mounted straight.  As mentioned in my previous article on progressives, there are laser etchings which define the layout of the lens.  After marking these it was clear they were not level.  They were close enough that my distance prescription was within tolerance (roughly equivalent to a 5 degree turn on the axis) but in practical terms this also means the reading areas do not overlap in my near zone.  This compounds the headache factor.


The Segment Height is uneven as well as the wrong height for both eyes, note the red line running just below the left pupil.

Next up is Seg Height.  As discussed above, if the glasses do not sit properly in front of the pupil, the reading can be challenging, and sometimes even the distance is bad if they sit too high.  As you can see from the above image, the heights on both eyes are not the same.  this was also a contributing factor on my experience of the headaches.

It’s very challenging to show accurately in a photo, but the Monocular PD was also off.  As described above in my discuss on head tilt, the total PD was accurate (61 mm) but the monocular was off, shifting both eyes off to one side.


Using a polariscope we can view the internal imperfections and stresses in a lens. The dark patches and rainbows at the corners indicate those imperfections.

The fish bowl sensation had my suspecting an issue with the lenses being cut too tightly into the frame, or perhaps an inferior grade of polycarbonate was used.  My inspection suggests this was indeed the case, as can be seen by the above image.  Using a device we call a polariscope I was able to make the internal stresses in the frame visible and as you can see the lenses are not uniformly clearly by any means of imagination.

The Low Down


Online Glasses aren’t all they’re cracked up to be. Shop with caution and low expectations

Online ordering of glasses can save you a little bit of money, but at a potentially high price.  The math of what I ordered for this online pair versus if I had ordered an equivalent product at my own office was maybe 40% savings, but they took the same amount of time to generate as it would if I had made them in my office, and I can wear them, albeit with a far bit of discomfort.

If you’re a financial pinch, have no insurance, but need glasses, this might be an OK way to go, but go in with some heavy warnings.  If you’re prescription has any astigmatism, if it is a progressive, I would most definitely warn you NOT to do an online ordering of glasses.  I think a recent patient of mine put it best:

“I learned the hard way.  Even with single vision, online is a waste of money.  They gave me migraine headaches. You have to spend the money to see properly and comfortably.” – Jennifer Carlson

As always I hope you found this informative, and hopefully at least a little entertaining.  If you have any questions, or topic ideas, please don’t hesitate to contact me here.





6 thoughts on “The Pitfalls of Online Glasses: The Review

  1. Pingback: Common Misconceptions | THE OPTICAL JEDI: A GUIDE TO THE MYSTERIES OF GLASSES

  2. I just seen a doctor but I did choose a frame that does not suit me at the shop afterwards. I ‘d now like to order a second pair online. I do not have progressive glasses and i have simple hyperopia. The shop was kind enough to disclosure my PD . Do you think this could be a quite safe situation to order online? Thanks so much, Cristina


      • Thank you , not astigmatism, just simple straight hyperopia. But i would be using them every day (i work with my computer ). My prescription seems pretty simple (+1.25, +3.00; nothing else is really written on it). I would not be doing it in normal times but considering the actual climate, i have to admit it is a quite a tempting option 🙂


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