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Are these two Rx different or the same?
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Are these two Rx different or the same?

My optometrist wrote an RX that looks like this:

OD  -2.25 sph     -0.25 cyl     150 axis     +2.50  Add
OS  -2.75 sph     -0.50 cyl     048 axis     +2.50 Add

My opthamologist wrote my RX this way:

OD  -2.50     +0.25     x 072
OS  -3.25     +0.50     x 143

These look (to me) to be completely different prescriptions.  Are they?  

Thanks...
1731421_tn?1358826971
Optometrists write in minus cylinder form (makes for smaller, thinner lenses), while ophthalmologists write in plus cylinder form (which translates into "surgical" talk). These prescriptions are actually almost the same. Go to a calculator online for "converting plus to minus cyliner."
Best of luck,
Timothy D. McGarity, M.D.
3 Comments
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1932338_tn?1349223998
Aren't the spheres still off significantly ?
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1731421_tn?1358826971
Nope.

Converting Minus to Plus Cylinder:
Add the magnitude and power of the cylinder to the sphere = New sphere power, then keep the magnitude of the cylinder the same, but change it's power to plus and rotate the axis by 90 degrees:

Your right eye:
-2.25 sph (+) -0.25 cyl =-2.50 sph ("new sphere")
-0.25 cyl 150 axis = +0.25 cyl 60 axis ("new cylinder in plus form")
-2.50 sph +0.25 cyl 60 axis
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