-4.75 cylinder

**SunnyNC** · 09-15-2007, 03:40 AM

A -4.75 cylinder is out of range for most manufacturers. Can a -1.50-4.75x065(example) be ground and does anyone know any specialty shops where I can have one ground.

Thanks
SunnyNC

**HarryChiling** · 09-15-2007, 03:42 AM

Yes it can be, in our shop or anyother lab out there. In this case I would choose the best base for the sph equiv or maybe try the resolution to see if it comes in an atoric that may help eliminate the aberrations.

**SunnyNC** · 09-15-2007, 04:16 AM

Whose lense do you use. -4.75 is out of the range for most lenses I look up

Thanks

**HarryChiling** · 09-15-2007, 04:23 AM

SV, FT, Prog? Out of range means nothing in terms of can it be done.

**obxeyeguy** · 09-15-2007, 07:01 AM

Out of range? Heck, yesterday I delivered -5.50 and a -6.00 cyl, (corneal transplants). Conventional tri with AR, took 4 days from my regular lab.

**Fezz** · 09-15-2007, 08:12 AM

Out of range? Holy smokes!

I dispensed a -7.50 cylinder in a Hoya Summit CD, Phoenix(Trivex) just last week.

-4.75 maybe a little tough for a mediocre lab to pump out, but any lab that has even a little skill should be able to produce that with no problem.

I agree that there may be certain lens combos that it will not work.

If your lab can not do it, I would tell them to check out "The Labs, Lab"

http://www.questopticallab.com/index.html

**Jacqui** · 09-15-2007, 08:40 AM

-4.75 is really not a big thing. If your regular lab has trouble contact www.laramyk.com

**DragonLensmanWV** · 09-15-2007, 09:16 AM

Originally Posted by Fezz

Out of range? Holy smokes!

I dispensed a -7.50 cylinder in a Hoya Summit CD, Phoenix(Trivex) just last week.

-4.75 maybe a little tough for a mediocre lab to pump out, but any lab that has even a little skill should be able to produce that with no problem.

I agree that there may be certain lens combos that it will not work.

If your lab can not do it, I would tell them to check out "The Labs, Lab"

http://www.questopticallab.com/index.html

I think the highest cylinder I've done is about 7.50 or so. Had a pair of twins, both +6.00 - 5.75. Weird thing is they both had oblique axis, each 90 degrees different from each other.

**Fezz** · 09-15-2007, 09:22 AM

Originally Posted by DragonLensmanWV

I think the highest cylinder I've done is about 7.50 or so. Had a pair of twins, both +6.00 - 5.75. Weird thing is they both had oblique axis, each 90 degrees different from each other.

Yeah this pretty job even had 4-base out OU!!!!!

OU-ch!!!

**optical24/7** · 09-15-2007, 09:36 AM

I think Sunny must be talking about stock lenses. As the others say, any lab that's not run out of a garage should be able to grind a 4.75 cyl.

**SunnyNC** · 09-17-2007, 09:42 AM

Have you dispensed an Essilor IPSEO -4.75 and what lab did you use?

Thanks

**Andrew Weiss** · 09-17-2007, 02:37 PM

SunnyNC, are you looking for a free-form progressive with that power cyl? Most of the free-forms I've used or know about top out at a -4.00 cyl. You might want to contact AWTech on this board, though; he may be able to help you.

**HarryChiling** · 09-17-2007, 02:44 PM

Now freeform in that high a cyl makes sense to ask the question. The equipment can definately handle this power, but the issue arises when during the polishing as the conformable laps might have a hard time with the high a cyl with any accuracy.

Just an idea, in a progressive if a SV blank were to incorporate the additional cyl on the front surface and have the progressive and remaining cyl ground onto the back surface, the limitations from the equipment can be overcome. I don't know if the software used to calculate these back side progreesives will allow for this, but my bet is that AWTECH might be able to do something like this if not completely place the cyl on the back surface.