What is another word for cup-to-disc ratio?
Pronunciation: [kˈʌptədˈɪsk ɹˈe͡ɪʃɪˌə͡ʊ] (IPA) 
Cup-to-disc ratio refers to the proportion of the cup (the indentation in the center of the optic nerve head) compared to the entire disc (the circular area surrounding the cup). Synonyms for cup-to-disc ratio include the cup-to-disc ratio itself, cup-disc ratio, CDR, optic cup disc ratio, and nerve head ratio. Other phrases that describe a similar concept include optic nerve excavation and optic nerve head morphology. These terms are commonly used in ophthalmology to describe the appearance of the optic nerve on examination and are important in the diagnosis and monitoring of conditions such as glaucoma.
