Free Form Materials

[skirk1975]

Why are free form lenses available in inly hi-index materials? Does this make any sense since CR39 is the clearest of materials to begin with? The answer I got from one rep of a company with a free form product is that CR39 is clear enough as it is so it doesn't need the free form as much as the 1.60 or 1.67. That answer is somewhat ridiculous. What does anyone else have to say about this ? :angry:

[Jacqui]

I've seen all materials except glass done as freeform. I think it may be a more apparent improvement with the higher index materials.

[AWTECH]

Free form materials

This non-spherical finishing process is possible on any material. This is the way the progressive molds are now made for injected lenses. The steel used for molds takes a great deal longer to machine. CR-39 is used but the optical clearness of the material is not a reason to use this type of technology. I think you will see the high indexes used with this process because this is a premium process and to make the thinest lenses the higher indexes accomplish this. I will not be very easy to see a patient on this technology if you are replacing a Poly PAL with a CR-39 free form PAL and charging a lot more for the product. The customer would then look at each product and say the free form is thicker and heavier, Why? There is not a good answer. Free from technologies need to be used where they will offer the greatest benefit to the patient. Price vs. technology is going to have to be figured into the mix.

[rolandclaur]

what exactly is free form guys?

[DocInChina]

what exactly is free form guys?

There was a thread about free form:

http://www.optiboard.com/forums/arch...hp/t-9341.html

Doc

[lensguy]

I have a freind in the UK who sent me a pkg from Rodenstock "Impression", a family of free form all materials. S.V., Office, sport progressive, sport S.V., Progressive reg, progressive short most in all index, 1.5, 1.6, 1.67, 1.74 and glass op to 1.8. ??????

Why cant these guys do better in North America???????

[For-Life]

A lot of them do it only in the high index materials because it is usually the companies best lens and they want to put it out as the best. Therefore it is available in a high index with AR and only in those specifications.

[rinselberg]

I think that the Shamir Autograph is a free-form progressive lens that is available in CR-39, 1.6 and 1.67 - in the United States.

[rinselberg]

I think that the (Essilor) DEFINITY progressive would also be available in "hard resin" (CR-39).

Andrew Karp, 20/20 Online

http://www.2020mag.com/index.asp?page=3_351.htm