Process of making a progressive lens

**rolandclaur** · 08-10-2005, 07:00 PM

I'm sure this is probably a really novice question to a bunch of the professional opticians on here, but because I have no experience in a surface generating lab, could somebody give me a brief synopsis on the process of how a progressive lens grows up from beginning to end in the frame's of a customer's glasses. Any information would be greatly appreciated. Thanks guys..

**OPTIDONN** · 08-10-2005, 09:43 PM

Not too much to it. Just gring the correct curves, either spherical of toric, on the back of the lens. Just like any other lens. Lens with a plus power often needs prism thinning, I think its .6 times the add power. This induces prism to make the lens look thinner. Thats just the super simple version of it.

**rolandclaur** · 08-10-2005, 11:02 PM

Progressive question
Remember it is not just the basic progressive design, as the final design is done by the lab surfacing the lens.

Depending on how they choose to layout the Rx the same lens design from the same manufacturer can be produced with great zone sizes or very limited zones.

How does the lab surfacing the lens actually influence the final design parameters of the progressive lens?? This quote was under the topic/thread of what good progressives are available in 1.67 in the progressive forum

**Jedi** · 08-10-2005, 11:42 PM

I'm not too sure what AWTECH was refering to, but I don't think the lab surfacing has any control over the final design of the progressive area, with the exception of base curve. Two progressive of the same design and RX surfaced on two different base curves (let's say a 4 and 8) will have different areas of progression, but one that is a little thicker or one that is prism thinned and one that is not should have very little differnce in the progression.

**rsandr** · 08-11-2005, 02:53 AM

Originally Posted by rolandclaur

I'm sure this is probably a really novice question to a bunch of the professional opticians on here, but because I have no experience in a surface generating lab, could somebody give me a brief synopsis on the process of how a progressive lens grows up from beginning to end in the frame's of a customer's glasses. Any information would be greatly appreciated. Thanks guys..

The progressive areas of the lens are moulded to the front surface, if you hold the lens flat in front of you this can be seen. (The boffins at Essilor work out what the front of the lens should look like, then the rest try to copy it :D.)

All the finishing lab really does is select a base according to the Rx and work the necessary curves to the rear. Much the same way as producing a bifocal, or for that matter a single vision.
As said vertical prism can be applied to make the lens thinner and the shape of the progressive zones is very much dependant on the base/add.

Rick

**Lewy** · 08-11-2005, 03:12 AM

Just wish the would abolish Prism thinning, causes more non tols than anything else. Don't forget with this free form generating, progressive surfaces are now being made individually, getting away om the fixed parameters of previous designs. Look at the some of the new lenses where you can specify what corridor length, inset etc that you require. Or the Ipseo that takes into account eye/head movement ratio, from what the techies told me last year there is something like 37,000 different progressive surfaces to use!

Lewy

**rsandr** · 08-11-2005, 03:22 AM

Originally Posted by Lewy

Just wish the would abolish Prism thinning, causes more non tols than anything else. Don't forget with this free form generating, progressive surfaces are now being made individually, getting away om the fixed parameters of previous designs. Look at the some of the new lenses where you can specify what corridor length, inset etc that you require. Or the Ipseo that takes into account eye/head movement ratio, from what the techies told me last year there is something like 37,000 different progressive surfaces to use!

Lewy

I am saving up for a free form lens lathe, but not holding my breath!

We surface lenses without prism thinning if the order specifies.

Rick

**rolandclaur** · 08-11-2005, 02:21 PM

thanks for all your guys input. I really feel like I won't get a complete grasp on progressive design until I actually get my hands dirty in a surfacing lab. Hopefully an independent lab here in san diego will allow me to intern or work there for free on a limited basis so I can really understand what goes on behind the scenes and comprehend the principles..