Posted by Jairo on 10/21/2019 to Progressive Lens Technology and Tips
How To Have The Thinnest Rx Lenses
Transcription of Video:
It's Your Progressive Lens Expert! You have a high near-sighted eyeglasses prescription and today I show you some techniques that you should coordinate with your optician so that you can end up having the thinnest lenses you could possibly have.
Most opticals owners, whenever they need employees on their sales floors, they hire them but they (optical owners) don't provide special training for optimizing myopic prescriptions on their customer's or patient's frames.
The opticals, they just want to sell you the most expensive highest index of refractions without considering any of the tips that I'm going to share with you today. So, you end up spending a lot of money, but your lenses are never as thin as they could possibly be.
Keep in mind, all of these techniques that I will share with you today, they're going to be for myopia as well as frames that have frames all the way around the orbital of the lens.
Tip #1 - Try to match your total Pupillary Distance to the Frame PD as close as possible. The frame PD is taken by having a ruler (in millimeters), then you'll begin measuring the zero mark at the point at which the lens will begin on the temporal side of the edge and you're going to measure all the way across to where the opposite lens begins on the nasal side. So it's, from this side (temporal edge tangent line) to here (nasal side tangent line on other lens).
In this case, the frame PD would measure 67 millimeters.
So, you take the total of the frame PD then you'll subtract it from your total Pupillary Distance and you want that number to be close as possible to zero. Now, it doesn't have to be zero, but you want that number to be as small as possible while still maintaining a good fit and a good look for your glasses.
And another way in which we optimize how thin your lenses can be is by talking about bevel placement. Bevel is the protruding V-shape that goes all the way around the edge of the lens that we then use to mount onto the frame. The bevel on the frame is the V-shape cavity that is carved into the frame so that the lens can fit in there. Think of it as the railroad tracks and the train.
Most places use a default measurement of one-thirds/two-thirds. Meaning, that they'll place the bevel 1/3rd to the front so that 2/3rds of the lens sticks out of the back.
We going to change that today. With a high Myopic Prescription, we're going to optimize the setting at 50/50. Meaning, half of the lens is going to stick out in the front and half of the lens is going to stick out to the back. Keep in mind the frame is going to cover most of the lens itself with only a little remaing on both the front and the back.
Next tip, don't choose frames that have excessive curvatures. High myopic prescriptions look best when they use flatter front base curves. So the closest to flat, the better. This, for example, is a great frame because it's flatter. It doesn't have a curve like this one. So, in high minus prescriptions, they flatter the frame... the better.
Don't choose frames that are higher than 5 base curve because even by the time you get to 6 (B.C.) is still really rounded. Try not to go this way.
When you choose frames that have a higher wrap and then you insert the flat lens into it, it's not compatible so when you force the frame to now fit the flatter bevel, the temples are going to flare out. So you don't want frames and temples that are going to be flaring out like this, because they are not going to fit well and they're going to be constantly falling off of your face.
Those frames that end up fitting this way, they're going to need extreme adjustments and by the time you force them into making them fit, they're not going to fit as well and they're not going to look as good either.
Next tip works really great, also. Order lenses that are Digitally Crafted, or in other words; free-form lenses.
Free-form lenses are digitally crafted lenses that are not molded, they are also not crafted by a diamond encrusted wheel. It is actually a diamond tip that carves point by point the prescription onto the back surface of the lens and they flip it and then they use it to carve the front surface of the lens, as well.
Now, these lenses have a high degree of customization which not only has the lenses looking great and thinner. So when you're looking through it, you have great contrast sensitivity and just overall the best optics possible.
What is special about these digitally crafted lenses is that we're able to now take measurements that you otherwise can't incorporate into the design of the lens.
There's three added measurements that ad to the quality of the optics. One of them being the Curvature of the Frame, the Pantoscopic Tilt (which has to do with how high or how low your ears are), and last the Vertex Distance (which is the distance from your Cornea to the lens itself). So all of these measurements are taken in the wearing position and therefore compensate the lens to have a prescription that's accurate to the 1/100ths of a Diopter.
And the last tip of How to Make or Make Your Lenses More Thinner Than Ever:
To Polish or Not To Polish that is the Shakespearean Dilemma that we put to rest today.
Weird Huh? How the color of the frame would influence the decision, Hmmm.
So you polish your lenses, only when the frame is going to be shiny. This is a great example because it is a crystal color, but it's shiny. A second example of a shiny finish on the frame: that is when you polish it.
When do you not polish the lenses? It's when you have a matte finish. These two examples are matte finishes, so you don't polish the lenses. And when frames share both characteristics so both shiny and matte finish or there's any question above, then that's when you comment below, tell me more about it and we can come to a great conclusion together. Or...Flip A Coin! Just Kidding!
Optics and aesthetics are my highest priority when crafting your lenses. That is usually the reason people ask me to make their glasses. I'm going to maximize my efforts and use every tool in my arsenal to make sure their lenses are as beautiful and as perfect as they could ever be..... Ever! Ever!