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Question: What do OU, OS, and OD stand for?


OD ………………… oculus dexter (the right eye)
OS ………………… oculus sinister (the left eye)
OU ………………… oculus uterque (both eyes


How do you pronounce “uterque”

Comment by GG — February 18, 2009

uterque — oo’TEHR’ kooeh

Comment by SR — July 23, 2009

thanks ,,,,,

Comment by lolla — August 13, 2010

I still can’t pronounce it :(
oo tehr kooeh
how do i say kooeh
like koo eh?
It’s such a hard name

Comment by Vivian — September 30, 2010

i was taught that OU stands for Ocular Universal

Comment by Hamza — November 12, 2010

“uterque” is pronounced:


Comment by jay — July 5, 2011

Uterque sounds a little like ‘you turkey’

Comment by Pam — September 27, 2011

thanks a lot for useful information.

Comment by Neda Salehi — October 23, 2011

thanks, this will help me very much

Comment by chamalka — November 9, 2011

thanks a lot & how to pronounced:?’ouoo turkey’

Comment by chandanie — November 9, 2011

this is very informative and interactive, no doubt everyone reading this is having fun while learning. I enjoy both the lectures and comments aswell. cheers.

Comment by ria cevangelista — January 13, 2012

When doing an exam, if I checked the right eye by covering the lefy and the left eye by covering the right, and they are both 20/20. Is it correct to put, OU 20/20 and OS 20/20? OR…can i document, OS 20/20? In other words, if they both tested 20/20, do I have to document them separately. Or can I simply put OU 20/20?
Thank you

Comment by Christina — March 1, 2012

Please ignore my previous question. I got my letters mixed up. The question below makes better sense. Thanks

When doing an exam, if I checked the right eye by covering the left and the left eye by covering the right, and they are both 20/20. Is it correct to put, OD 20/20 and OS 20/20? OR…can i document, OU 20/20? In other words, if they both tested 20/20, do I have to document them separately. Or can I simply put OU 20/20?
Thank you

Comment by Christina — March 1, 2012

You have to document it as OD 20/20 and OS 20/20. OU 20/? means the vision you are getting without covering either eye.

Comment by Robert — April 17, 2012

The explanation is very helpful. Just wondering, “oculus dexter”, “oculus sinister” and “oculus uterque”, are they Latin or other language origins? Thanks.

Comment by Tracy Dou — May 3, 2012

They are Latin!

Comment by Mrugesh Shah — May 14, 2012

OU OS and OD are for accurately documenting each or both eye, since the pronunciations are in Latin, we must understand that Latin is considered a dead language, so I feel pronunciation is not as important as understanding the symbolism.

Comment by Max — May 28, 2012

I just started working in Patient Services in an eye care practice and have wondered all week what OS, OD and OU actually mean–thank you for answering my burning question so clearly!

Comment by Regina — June 10, 2012

If a patient’s RX reads -.25 pl OS -.25 pl OD with a 2.50 ADD and is having double vision when reading what is the medical term for the problem there are 2 ?

Comment by Ernie — July 29, 2012

I made a mistake on my question:(it’s supposed to say when they have double vision watching TV ?there are 2 names for this problem,what are the names.

Comment by Ernie — July 29, 2012

How do I document that eye drops were administered one drop in each eye.
igtt ou??

Comment by Liz — December 11, 2012

Yes Liz… That is correct

Comment by Tina — December 24, 2012

Great job buddy :)

Comment by Binoy — May 29, 2013

I am buying contacts and the site I am buying them from is asking Right Eye (OD) and Left Eye (OS) then theres a dropdown list under each and I am rather confused what that is about? Would someone please explain to me what the drop down lists are about that have -1 to – 10? I really dont understand what its about, and I cant purchase the contacts until those fields are filled out.

Comment by Cady — June 29, 2013

OD = Oculus Dextra
OS = Oculus Sinistra
OU = Oculus Uterque.

I am also looking for the pronunciation of OU. It’s not even on howjsay.com and I have been able to find all other medical pronunciations there.

Comment by chiffonade — July 4, 2013

i have : OD: sphere -3.50
cylinder -0.50
axis 020
OS: sphere -2.00
cylinder -0.50
axis 175
So how many degree i have at the right eyes and the left eyes?

Comment by Vanessa Tran — October 16, 2013

i have
OD. +25 sphere. -50 cylinder. 020. Axis. And. OS. + 50 sphere. -50. Cylinder. 125. Axis. And. + 200. + 200. Prism. Please make me understand. How bad my eyes are ? I would appreciate if you could explain in simple terms. Than you

Comment by Lajya. Karrol — December 3, 2013

Vanessa and Lajya … if you want to understand the components of your glasses prescription, you may want to watch this video lecture I created on optics:


Comment by Timothy Root, M.D. — December 6, 2013

How sinister of the profession to carry on the notion that we lefties are somehow inferior or less able than those of us who are Dexterous. Left and Right would be clearer, simpler. Not sure I like having an eye that is thought of by the trade as sinister!

Comment by Larry G — March 3, 2014

this is the first time to know these abbreviation many thanks for your help

Comment by ali — March 30, 2014

thanks dear firend

Comment by mohammad-iran — April 18, 2014

oh thankyou

Comment by jordynn — June 22, 2014

Wonderful to know what these OD’s and Os etc mean

Comment by Charles Hall — August 5, 2014

Very fine explanations. No more guessing for me. The Southpaw thing helps remember OS

Comment by Charles Hall — August 5, 2014

Thanks a lot it is very useful for me

Comment by Jaya Kumari — September 25, 2014

what is O.E

Comment by subaby — October 19, 2014

i had a medical examination and i heard the doctor said .5 OU.. what does that mean?

Comment by macky — November 15, 2014

It is read as OO-TER-KWE , Oi-KU-LUS (yes, Oi) OO-Ter-Kwe.

Comment by Neil — December 1, 2014

Macky: The doctor was describing the “cup-to-disk ratio” to describe your optic nerve. A large ratio, such as 0.6 or higher, is a potential sign of glaucoma. You can read more about cupping here.

Comment by Timothy Root, M.D. — December 14, 2014

This was really great how you explained all these symbols and the comments. This could not be any better. Thank You

Comment by Charles Hall — December 23, 2014

Sorry to nitpick, but it should be “oculi uterque”.

Oculus dexter = right eye
Oculus sinister = left eye
Oculi uterque = both eyes
(“Oculus uterque” = “both eye”)

I’ve always pronounced uterque as “you-TER-kwey”, but I guess “ooh-TER-kwey” is probably truer to the original Latin pronunciation.

Love the site and purchased your OphthoBook by the way Dr. Root – keep up the amazing work!

Comment by Sami — January 8, 2015

Dr. Tim I owe you a lot for learning from your book. I thank you so much for your holy service to students like me without expecting anything.

Comment by Solai — January 26, 2015

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