1.What is the cup-to-disc ratio? The cup-to-disc ratio is the ratio between the diameter of the outer disc of the optic disc (optic papilla) and the diameter of the physiological depression of the optic papilla. It is one of the bases for the diagnosis of glaucoma. When the physiological depression is enlarged and the nasal deviation of the optic papilla vessels causes the cup-to-disc ratio to become larger than 0.6, glaucoma screening is needed. 2. How is the cup-to-disc ratio measured? The cup-to-disc ratio can be measured by direct fundoscopic gross measurement, OCT optic papillometry, and fundus photography. Different doctors’ interpretations may affect the results slightly, especially by direct fundoscopy. 3.What is the normal value of cup-to-disc ratio? The normal value of the cup-to-disc ratio is 0.3 or less. A value greater than 0.6 indicates that glaucoma may need to be investigated. 4.How can I tell if the cup is physiologically large or caused by glaucoma? A balanced disc along each quadrant is usually a physiological large visual cup. 5.Does the cup-to-disc ratio continue to increase as the disease progresses? The cup-to-disc ratio will continue to increase as the disease progresses. If the cup-to-disc ratio becomes larger, it means that it may be glaucoma, and further evidence needs to be sought for a temporary observation and intervention if necessary. 6. Is a child’s cup-to-disc ratio the same as that of an adult? The cup-to-disc ratio of children is the same as that of adults. The problem will be treated in the same way when it is found, and family history will be followed up.