I still quite vividly remember during my pre-registration year as an Optometrist commenting to a patient we’d been seeing for a few years “You didn’t change your spectacles after your last eye examination did you?” She hung her head shamefacedly and said “Well actually, I got some spectacles from El Cheapo in town” before adding, in quite scandalised tones “But I wouldn’t *dream* of going there for an eye examination!!” This mystified me completely, and I couldn’t help but blurt “Well if you don’t trust them to do a decent eye examination, why on *earth* do you trust them to make your specs?!”
The fact of the matter is that the general public have absolutely no idea how much expertise actually goes into making a pair of spectacles, quite how many things there are that can be screwed up, or why purchasing spectacles over the internet can be quite such a poor investment.
Now I know what you’re thinking here. You’re thinking that naturally an Optometrist is not going to want you to buy spectacles over the internet. Well, I’ve been self-employed for around 8 years now: I don’t own a practice and I don’t work on commission. My motivation and job satisfaction are derived from ensuring that your eyes are perfectly healthy and I’ve gotten your vision as good as humanly possible, and after that, to be quite frank, I’m indifferent to where you purchase your spectacles (hopefully the bosses of the places I work didn’t read that!). If however I later discover that the fantastic vision I painstakingly created has been degraded by shoddy spectacles, indifference morphs into incensed Optom quicker than you can say “El Cheapo”!
If you ordered an item of clothing from a catalogue, how surprised would you be if it didn’t fit? Not even remotely, I’m willing to wager. Choosing a frame isn’t just about fashion. When learning our craft, we Opticians soon learn that the variety of facial measurements is immense (also, everyone is a little wonky!). Plastic frames are the greatest offenders for poor fit since the fit on the bridge of the nose can’t be altered (DOs, before you comment in droves, I know the bridge can be bumped, but it looks hideous!), but even then there remains temple width, head width, side length, angle of side, nose-pad angle, nose pad splay, frame depth….still expecting an internet bought frame to fit?
Let’s assume for the sake of my sanity that El Cheapo Online manage to get the main 3 elements of a straight forward prescription (sphere, cylinder and axis) correct. The optical centre of your lens needs to be aligned with the centre of your pupil. If it is not, this induces prism. Prism is prescribed to correct an imbalance in someone’s eye muscles. Conversely, prism given to someone who doesn’t need it will throw their eyes off balance, and can cause eye strain, headaches and Optometrists to hop up and down with rage.
With a varifocal lens, the lens has to be positioned at the correct height within the frame, such that the patient’s distance prescription is aligned with the centre of their pupil when looking straight ahead. The power of the lens then changes gradually as you work your way down from that point towards the lower rim of the frame, such that the patient’s reading prescription is encountered anywhere from 15 to 25 (depending on the type of varifocal) millimetres lower. If a varifocal lens is sitting a mere millimetre too high, your distance vision will be slightly blurred because you’re not looking through the correct prescription for distance viewing. The fitting height therefore depends, not only on the frame chosen, but how that frame sits on the patient’s face. El Cheapo Online, unless they’re straying into the dodgy realms of illicit webcams, have not only not seen the patient’s face, but have not seen that particular frame on that particular patient’s face. I’m sure a bookie somewhere could work out the odds of El Cheapo Online managing to centre that varifocal correctly, but my terminology would be “slim to none”.
This article really only scrapes the tip of the iceberg in spectacle dispensing, but I will close with this. It takes three years to qualify as a Dispensing Optician for a reason: there’s a bloody lot of expertise going into dispensing your spectacles!