How To Transpose an Eyewear Prescription Easily

by admin on 27/04/2009

Learn how to transpose an eyewear prescription easily inside by learning a few simple rules!


For those just coming into the world of optics, prescriptions can be confusing.  However, learning to read them and work with them is easier than what comes to the naked eye.  Transposing a prescription is one of the most common actions when working in an optical laboratory, doctor’s office or even on a retail floor when an optician.  Some eye doctors prescribe eyeglasses in what is called plus cylinder, and others do so in minus cylinder.  Regardless of which is used, the prescriptions are the same.  This can be proven by transposing the eyewear prescription.

For instance, if one takes an eyewear prescription with OD -2.75 -1.00 x 25, one can transpose this rather simply with a few steps in mind.

First, the sphere power needs to be changed by adding the second number or cylinder power to it.  The result will be as follows: OD -3.75 -1.00 x 25.

Next. the second number, or cylinder power, will always have a sign change when transposed.  Therefore, the second change from in the original eyewear prescription will be OD -3.75 +1.00 x 25.

Finally, and one of the most important steps is to add 90 degrees to the axis, which is the last number in the prescription.  This gives you a totally transposed prescription that looks like the following:

-3.75 +1.00 x 115

Both the -2.75 -1.00 x 25 and -3.75 +1.00 x 115 are the same prescription(Rx), and they appear totally different!  It is just that simple.

Optical laboratories tend to work in minus cylinder as this is the way the lenses are ground for the final product, therefore, it is vital for not only lab technicians to know but crucial for an Optician.

 

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{ 15 comments }

NANCY November 24, 2010 at 09:15

TRANSPOSE A PLUS CYL TO MINUS CYL
-2.00+0.50X25
-2.00+0.50X148

admin December 3, 2010 at 07:47

-1.50 -.050 x 115
-1.50-0.50 x 058

Bhupesh Nagpaul January 4, 2011 at 03:32

I’m appearing for my ABO / NCLE exam in May 2011. I’ve been practicing Opticianary in India for last 20 years. Where can I get any relavent reading material so that I can refresh my memory. we don’t have a Board of Dispencing Opticians/ council in India so needless to say we don’t have any certification and hence no reading material. I’ll be oblidged if you could help me with the reading material.

Thanks & with Best Regards

Bhupesh Nagpaul

admin January 11, 2011 at 06:49

Contact ABO certification and licensing website – http://www.abo-ncle.org/… they can send you a list of books and you can purchase! :)

alex February 18, 2011 at 09:58

I think this website is helpful to those want to get the ABO an NCLE certificate. So, I already pass it, but I got several sleepless nights.

Stephanie March 29, 2011 at 17:38

so if I add 90 degrees to axis 148. That is 238 degrees Do I start all over and he axis is 058 degrees…………………….

admin April 15, 2011 at 05:36

Yes, simply start over at 058. Exactly right!

stacy May 17, 2011 at 16:16

Hi, I have to get transition lense. Can you tell me what this mean
right -0.25/ 0.50 x 75
left -0.25 / 0.50 x 115

admin May 19, 2011 at 19:15

It only means that you have a low…very low astigmatism with no need for a bifocal, therefore, all you need is single vision lenses. Your vision is very good and you can see to function without glasses however for certain tasks you may have slight issue. Transitions lenses are prescribed for those with sensitivity to sunlight as it protects against UV rays, and changes when you go in and out as far as tint automatically.

mir imtiyaz July 29, 2011 at 21:50

how can we transpose the following ;-1.50/-1.oo 75.addition 2.00both

admin August 10, 2011 at 15:24

Assuming you mean -1.50 -1.00 x75 with a 2.00 Add Power
-2.50 +1.00 x 105 with 2.00 Add Power and if you want to make the entire thing a single vision Rx, +0.50 -1.00 x 75 (the cylinder power and axis remains the same in this instance. Only add the Add power to sphere power)

michelle September 27, 2011 at 08:00

transpose this rx -1.00 +3.00 x 180 OD and -3.25 +3.00 x 088

admin October 9, 2011 at 17:26

+2.00 -3.00×90 and -0.25 -3.00×178

Oluchi October 12, 2011 at 06:50

I think the first prescription is from the optometrist,then the pransposed is what the patient will wear,or do the doctor do the Rx and the transposition as well before the optician can do his job?

admin October 15, 2011 at 16:12

Generally, the doctor will write a prescription, and if the prescription is in + cylinder, the optician or lab technicians will transpose the prescription to make the lenses for the frame. Both the transposed Rx and the original Rx are the same, just written in a different form. Docs can write the Rx in either form however.

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