If you have just had an eye examination and the optometrist has given you a glasses prescription, they likely mentioned that you are short-sighted or long-sighted, or that you have astigmatism. We at KSA Silmakeskus will be explaining how to read a prescription over the coming weeks.
But what do all those numbers on your glasses prescription mean? And what about all those abbreviated terms, such as OD, OS, SPH and CYL?
We will help you decipher your prescription so that next time you can discuss glasses with the optician like an expert.
What OD and OS mean
The first step in understanding a glasses prescription is knowing what "OD" and "OS" mean. These are abbreviations of oculus dexter and oculus sinister, which are the Latin terms for the right eye and the left eye.
Your glasses prescription may also have a column labelled "OU". This is an abbreviation of the Latin term oculus uterque, meaning "both eyes".
Although these abbreviated Latin terms are used on prescriptions for glasses, contact lenses and eye medications, some doctors and clinics have chosen to update their prescriptions and use RE (right eye) and LE (left eye) instead of OD and OS.
On your glasses prescription, the information for your right eye (OD) appears before the information for your left eye (OS). Eye doctors write prescriptions this way because when they look at you, they see your right eye on the left (first) and your left eye on the right (second).
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