cup-disc ratio


Also found in: Acronyms.

ratio, cup-disc (C/D) 

The ratio of the horizontal diameter of the physiological cup to that of the horizontal diameter of the optic disc. It should be less than 0.5. If it exceeds that value, or if there is a difference in ratio between the two eyes, or if there is a progressive enlargement of the cup, glaucoma may be suspected (Fig. R1). See glaucomatous cup.
Fig. R1 Diagram of the physiological cup with a cup-disc ratio of 0enlarge picture
Fig. R1 Diagram of the physiological cup with a cup-disc ratio of 0
References in periodicals archive ?
13) Describe an abnormal optic disc in terms of its cup-disc ratio, and report visual loss to the ophthalmologist as a defect in a respective field quadrant as detected on confrontational visual field testing or as an afferent pupillary defect in a given eye.
20 IOP <21 mm Hg Cup-disc ratio, stereoscopic 2 photography (14) Cup-disc ratio >.
Now let's assume that ophthalmoscopy reveals a cup-disc ratio of 0.