What is the diameter of the optic disc in millimeters?

What is the diameter of the optic disc in millimeters?

• A. 1.75 mm
• B. 1.25 mm
• C. 2.0 mm
• D. 1.5 mm

Answer: (A)

The diameter of the optic disc is typically described as about 1.75 mm. This value is a commonly used reference average in ophthalmology for estimating cupping and comparing discs across patients. In practice, the disc size can vary, usually within roughly 1.5–2.0 mm, but 1.75 mm sits near the standard reference most texts and exam materials use. Larger or smaller values are possible, but 1.75 mm best represents the typical average when discussing the optic disc diameter. The measurement is taken across the widest span of the disc (horizontally), and individual factors like axial length can cause variation, which is why clinicians interpret cupping in the context of the patient’s overall eye size.

The diameter of the optic disc is typically described as about 1.75 mm. This value is a commonly used reference average in ophthalmology for estimating cupping and comparing discs across patients. In practice, the disc size can vary, usually within roughly 1.5–2.0 mm, but 1.75 mm sits near the standard reference most texts and exam materials use. Larger or smaller values are possible, but 1.75 mm best represents the typical average when discussing the optic disc diameter. The measurement is taken across the widest span of the disc (horizontally), and individual factors like axial length can cause variation, which is why clinicians interpret cupping in the context of the patient’s overall eye size.