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converting CL rx to Spectacle Rx??

This is a discussion on converting CL rx to Spectacle Rx?? within the ECP Corner forums; Is there a conversion calculator for converting a patients contact lens Rx to a spectacle ...


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  #1 (permalink)  
Old 11-30-2011, 11:25 AM
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Default converting CL rx to Spectacle Rx??

Is there a conversion calculator for converting a patients contact lens Rx to a spectacle Rx. Our patient has a CL Rx of -19.00/-2.50 and my charts only go up to -12.00. Any suggestions?

Last edited by bglab; 12-01-2011 at 08:54 AM..
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  #2 (permalink)  
Old 11-30-2011, 12:15 PM
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Posts: 311
Default Converting a Contact Lens Prescription to Glasses

Quote:
Originally Posted by bglab View Post
Is there a conversion calculator for converting a patients contact lens Rx to a spectacle Rx. Our patient has a CL Rx of -19.00/-2.50 and my charts only go up to -12.00. Any suggestions?
This question as been addressed in this forum before, in one case the thread that resulted from such a question grew to almost 250 posts.

The good news is that post #2 gives a formula for converting a glasses prescription to a contact lens one. The bad news is that it doesn't show how to convert a contact lens prescription into a glasses one. I looked around but when I finally found a chart, it only went to like a -11 prescription.

It's interesting that you ask this question and talk about "our patient." Don't you have some kind of conversion manual in your office for this sort of thing? If you know the formula, you can just plug in the numbers. The formula looks something like this:

Fcl = Fsp * (1 - (d/Fsp)
Fcl = 1/contact lens power in diopters ie -6.00= -0.167
Fsp = 1/spectacle lens power in diopters ie -6.50= -0.154
d = distance from the eye to the spectacle lens in meters usually 12mm = 0.012

That formula and making the conversion are covered here:

http://www.lens101.com/general-contact-lens-care-questions/3599-converting-glasses-prescription-into-contact-lens-prescription.html
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  #3 (permalink)  
Old 11-30-2011, 12:25 PM
Contact Lenses Forum - Ph.D.
 
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DONT be a cheap skate and go back to your eye doc and have him or her convert it back for you!

both eye glass and contact lens prescriptions can differ depending on the fit and curvature of the contact lenses.
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Old 11-30-2011, 12:52 PM
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Quote:
Originally Posted by luvbostonxo2's View Post
DON'T be a cheap skate and go back to your eye doc and have him or her convert it back for you!

both eye glass and contact lens prescriptions can differ depending on the fit and curvature of the contact lenses.
Yeah, I think I would prefer to go back to the eye doctor rather than try to do the calculations myself.
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  #5 (permalink)  
Old 11-30-2011, 02:02 PM
Contact Lenses Forum - Ph.D.
 
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Quote:
Originally Posted by bglab View Post
Is there a conversion calculator for converting a patients contact lens Rx to a spectacle Rx. Our patient has a CL Rx of -19.00/-2.50 and my charts only go up to -12.00. Any suggestions?
If your an ecp u should know better. apply your vertex distance....then do an over refraction to test the power. You should know this by heart without looking at a chart!!!!!!

!?!?!?!?!?!? DUH!
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  #6 (permalink)  
Old 11-30-2011, 02:49 PM
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Quote:
Originally Posted by luvbostonxo2's View Post
If your an ecp u should know better. apply your vertex distance....then do an over refraction to test the power. You should know this by heart without looking at a chart!!!!!!

!?!?!?!?!?!? DUH!
Okay, I thought that was a bit odd, too, that someone talking about having patients was looking for a conversion chart. It seems like R2D2 was a little confused about that as well.

Still, I think "DUH!" is a bit strong.
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  #7 (permalink)  
Old 11-30-2011, 03:28 PM
Contact Lenses Forum - Ph.D.
 
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Quote:
Originally Posted by Eagleye View Post
Okay, I thought that was a bit odd, too, that someone talking about having patients was looking for a conversion chart. It seems like R2D2 was a little confused about that as well.

Still, I think "DUH!" is a bit strong.
I know it was...but think about it this way.....THIS ecp actually has patients....*shakes head*

Its scary to know that even in this field (without sayn something mean) there are ecp's that dont know as much!

Frightful that an ecp has to consult a chart.......wowowowoo!?!?!?!?!
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  #8 (permalink)  
Old 11-30-2011, 04:01 PM
Contact Lenses Forum - Bachelors Degree
 
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Default What Do You Say?

Quote:
Originally Posted by luvbostonxo2's View Post
I know it was...but think about it this way.....THIS ecp actually has patients....*shakes head*

Its scary to know that even in this field (without sayn something mean) there are ecp's that dont know as much!

Frightful that an ecp has to consult a chart.......wowowowoo!?!?!?!?!
Have you got anything to say about this now that you've started this thread, bglab?
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  #9 (permalink)  
Old 11-30-2011, 04:53 PM
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Quote:
Originally Posted by bglab View Post
all of this and no one person is of any help! other than being rude, if you don't have anything constructive to say don't say anything!!
You didn't like R2D2's link to that page that has the calculations? It didn't make a whole lot of sense to me, but I figure someone who fits their own patients might be able to use all those numbers and letters.
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Old 11-30-2011, 05:11 PM
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Default

Quote:
Originally Posted by luvbostonxo2's View Post
I know it was...but think about it this way.....THIS ecp actually has patients....*shakes head*

Its scary to know that even in this field (without sayn something mean) there are ecp's that dont know as much!

Frightful that an ecp has to consult a chart.......wowowowoo!?!?!?!?!
It seems a little strange to me as well, but I'm not an ECP and so I'm willing to give bglab the benefit of the doubt.
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  #11 (permalink)  
Old 11-30-2011, 07:57 PM
Contact Lenses Forum - Ph.D.
 
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Quote:
Originally Posted by AllyCat View Post
It seems a little strange to me as well, but I'm not an ECP and so I'm willing to give bglab the benefit of the doubt.
Heres my take.....the OP in my opinion is NOt an ecp but rather posing as one to get someone like me who is an ecp to convert his or her prescription so that they can order their contacts online.....I don't have a problem with that!

So here's a thought...why not just SAY that u are NOT an ecp and NOT be cheap and have your ecp do the conversion for you....!?!?!?!?

IF the original poster was an ecp they wouldnt have been asking that WEIRD original question!>!?!?!??

Im just sayn!!!!

PS> its like sayn (if yer a car mechanic) "hold on and let me see the step by step procedure chart on how to change YOUR brake pads"

lol
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  #12 (permalink)  
Old 12-01-2011, 12:06 PM
Contact Lenses Forum - Bachelors Degree
 
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Default

Quote:
Originally Posted by luvbostonxo2's View Post
Heres my take.....the OP in my opinion is NOT an ECP but rather posing as one to get someone like me who is an ECP to convert his or her prescription so that they can order their contacts online.....
That's quite a presumption there, luvbostonxo2's. I hope you're right, or things might get ugly.

Here's a thought. When bglab said "our patient," maybe he or she works in a doctor's office, but not as a doctor. I know a woman who schedules appointments at a doctor's office and often says things like "we had a patient the other day who was unbelievable." It wasn't her patient, but it was a patient whom she met while at work.
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  #13 (permalink)  
Old 12-02-2011, 08:56 AM
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Default

Your post doesn't make any sense. The OP has a CL script and wants to convert it to a spectacle script.

An ECP could use one of the contact lens conversion tools. Just keep changing the spectacle script until you match the current CL script.

That's only an "academic" answer. The ECP needs to refract the patient. CLs are generally available in .50 power increments. There is rounding involved.



Quote:
Originally Posted by luvbostonxo2's View Post
Heres my take.....the OP in my opinion is NOt an ecp but rather posing as one to get someone like me who is an ecp to convert his or her prescription so that they can order their contacts online.....I don't have a problem with that!

So here's a thought...why not just SAY that u are NOT an ecp and NOT be cheap and have your ecp do the conversion for you....!?!?!?!?

IF the original poster was an ecp they wouldnt have been asking that WEIRD original question!>!?!?!??

Im just sayn!!!!

PS> its like sayn (if yer a car mechanic) "hold on and let me see the step by step procedure chart on how to change YOUR brake pads"

lol
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  #14 (permalink)  
Old 12-02-2011, 09:51 AM
Contact Lenses Forum - Bachelors Degree
 
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Location: United States
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Default Might Be Useful

Quote:
Originally Posted by lurker2010 View Post
An ECP could use one of the contact lens conversion tools. Just keep changing the spectacle script until you match the current CL script.
Is that conversion tool available on line for members of Lens 101 to use?
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  #15 (permalink)  
Old 12-15-2011, 11:43 AM
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Default I Wanna See It

Quote:
Originally Posted by KITT View Post
Is that conversion tool available on line for members of Lens 101 to use?
Yeah, I'd like to see something like that if it's not too complicated.
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  #16 (permalink)  
Old 12-17-2011, 12:22 AM
Contact Lenses Forum - Ph.D.
 
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Quote:
Originally Posted by lurker2010 View Post
Your post doesn't make any sense. The OP has a CL script and wants to convert it to a spectacle script.

An ECP could use one of the contact lens conversion tools. Just keep changing the spectacle script until you match the current CL script.

That's only an "academic" answer. The ECP needs to refract the patient. CLs are generally available in .50 power increments. There is rounding involved.
lets just say an ecp does not require "CHARTS".....id be scared and take my biz elsewhere.

Contact lens prescriptions and Eye glass prescriptions are not interchangeable!!! AND cannot be backward or forward converted.

EX. a toric eye glass prescription may ONLY require a slightly stronger spherical contact lens.

EX. power may be reduced or increased in one or both eyes based on fit of the contact lens on the eye.

if u convert using a chart.....is usually 99% incorrect so thats why we ECP's do not use or need them. We also need to do a refraction to test visual acuity.

PS. op cl rx to spec rx..!?!?!?

Last edited by luvbostonxo2's; 12-20-2011 at 04:35 AM..
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  #17 (permalink)  
Old 12-19-2011, 04:55 PM
Contact Lenses Forum - Senior
 
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Default

Quote:
Originally Posted by luvbostonxo2's View Post
PS. op cl rx to spec rx..!?!?!?
Is that Eye Doctor Code meant to test bglab? I think I know what it means. I'm not an eye doctor, but I sure learned a lot from Lens 101.
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  #18 (permalink)  
Old 12-20-2011, 09:35 AM
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Join Date: Jan 2010
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Default

Quote:
Originally Posted by luvbostonxo2's View Post
lets just say an ecp does not require "CHARTS".....id be scared and take my biz elsewhere.
I suspect an ecp shouldn't need a chart or conversion tool for most contacts. Does an ecp need tools (convertor calculator) for patients with astigmatism (toric lenses)?

I'm not going to post a link. People can use goggle to find conversion calculators. People who are too lazy or too stupid to find a tool on their own have no reason to be using one. There are very few reasons why a member of lens101 needs to use a convertor. You can't get contacts (most countries) without a script and I'd run from any ECP who needs my help in determining which contacts try based on my spectacle script.
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  #19 (permalink)  
Old 12-20-2011, 09:52 AM
Contact Lenses Forum - Bachelors Degree
 
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Default Sorry About That

Quote:
Originally Posted by bglab View Post
Is there a conversion calculator for converting a patients contact lens Rx to a spectacle Rx. Our patient has a CL Rx of -19.00/-2.50 and my charts only go up to -12.00. Any suggestions?
See what you started bglab? Ask a simple question about a conversion calculator and use the phrase "our patient" and people jump all over you. They took it upon themselves to judge you instead of just helping you. I hope you found the information you needed from somewhere. Looks like the big shots at Lens 101 are too busy finding fault to try to help. Sorry.
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  #20 (permalink)  
Old 12-21-2011, 07:03 PM
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Default

My chart goes up to -/+ 30.00. If Rx is -19.00-2.50x?, then Sph is -15.25 and second meridian is -17.25, so Cyl is actually now -2.00.
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  #21 (permalink)  
Old 12-22-2011, 10:16 AM
Contact Lenses Forum - Senior
 
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Default I'll Take Your Word For It

Quote:
Originally Posted by Contact Lens Fitter View Post
My chart goes up to -/+ 30.00. If Rx is -19.00-2.50x?, then Sph is -15.25 and second meridian is -17.25, so Cyl is actually now -2.00.
If you say so . . .
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  #22 (permalink)  
Old 02-03-2012, 03:08 PM
Contact Lenses Forum - Bachelors Degree
 
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Quote:
Originally Posted by lurker2010 View Post
I'm not going to post a link. People can use goggle to find conversion calculators. People who are too lazy or too stupid to find a tool on their own have no reason to be using one. There are very few reasons why a member of lens101 needs to use a convertor.
What if I'm just curious to see one of those conversion charts? There's so much talk about them here. Just because I want to see what a conversion take looks like doesn't mean I want to use it to convert my own glasses prescription to a contact lens prescription. What would I use it for anyway? To scribble down some numbers and then try to buy contact lenses?

Of course, since I'm stupid and lazy like you say I am, I won't even do that, so what's the harm it letting me see a conversion chart? Maybe I just want to stare at it in wonder like the monkeys on 2001: A Space Odyssey.
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Old 02-04-2012, 09:55 AM
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REMEMBER-the conversion chart is just a STARTING POINT. The resulting numbers may not give you the best vision. The number that will give you the best vision is the strength that you need, and that can only be done the same way as the Dr's test. "is this better or is this better'? YOU tell the Dr what you need by answering this question. The same is true with Rx conversion. You have to try an Rx and see how the vision is. If it's not good, do an 'over-refraction'.
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Old 05-11-2012, 02:26 AM
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Default Need help

I have been to the eye doctor and have been with the same contacts for yrs but my prescription has changed and I don't have money for a contact lens exam. I just got my prescription with an OD of -8.25, cylinder of -1.00 and axis of 172 and the OS is -8.50, cylinder of -0.50 and axis of 25. My old contact box says an Os and Od of -8.00, BC of 8.4 and DIA of 14.0. Please help I am not good with math and don't understand the math formula.
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Old 05-13-2012, 06:55 PM
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Quote:
Originally Posted by aprilitaw View Post
I have been to the eye doctor and have been with the same contacts for yrs but my prescription has changed and I don't have money for a contact lens exam. I just got my prescription with an OD of -8.25, cylinder of -1.00 and axis of 172 and the OS is -8.50, cylinder of -0.50 and axis of 25. My old contact box says an Os and Od of -8.00, BC of 8.4 and DIA of 14.0. Please help I am not good with math and don't understand the math formula.
You can't buy contacts (US) without a current contact lens script. The value of the free trial lenses you'll get from your ECP should offset much of the incremental cost for the contact lens exam.
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Old 05-15-2012, 09:57 AM
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Quote:
Originally Posted by lurker2010 View Post
You can't buy contacts (US) without a current contact lens script. The value of the free trial lenses you'll get from your ECP should offset much of the incremental cost for the contact lens exam.
Thank you for that reminder. Once in a while someone asks about getting contact lenses without being fitted for them by a doctor and they need to be reminded to seek professional help.
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Old 12-04-2012, 01:29 AM
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PLEASE try to remember, we are NOT digital. Vision is determined by the brains interpretations of the image it receives. NOT THE NUMBERS !!!!
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Old 01-22-2013, 02:42 AM
Contact Lenses Forum - Ph.D.
 
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Thumbs up

Quote:
Originally Posted by aprilitaw View Post
I have been to the eye doctor and have been with the same contacts for yrs but my prescription has changed and I don't have money for a contact lens exam. I just got my prescription with an OD of -8.25, cylinder of -1.00 and axis of 172 and the OS is -8.50, cylinder of -0.50 and axis of 25. My old contact box says an Os and Od of -8.00, BC of 8.4 and DIA of 14.0. Please help I am not good with math and don't understand the math formula.
eyeglass prescriptions are different than contact lens prescriptions. You have astigmatism and the only way to get a successful fit is to get a contact lens exam. Success with contact lenses begins with a proper fitting and CONTACT LENS exam.
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Old 02-15-2013, 05:29 PM
Contact Lenses Forum - Bachelors Degree
 
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Quote:
Originally Posted by luvbostonxo2's View Post
You have astigmatism and the only way to get a successful fit is to get a contact lens exam. Success with contact lenses begins with a proper fitting and CONTACT LENS exam.
Bonus points to luvbostonxo2's for not saying "an astigmatism." I see that almost every time I visit.
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Old 07-17-2013, 10:38 AM
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Default

Quote:
Originally Posted by Garfield21 View Post
Bonus points to luvbostonxo2's for not saying "an astigmatism." I see that almost every time I visit.
Lol! Also the axis contact lens position is important as well and contacts lenses may have a different axis to achieve that fine balance of toric correction and crisp clear vision!
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