What is the diameter of the optic disc in millimeters?

What is the diameter of the optic disc in millimeters?

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

Answer: (D)

The optic disc diameter is the size of the eye’s optic nerve head as seen on fundus examination and imaging. In most adults, the physiological disc measures about 1.5 to 2.0 mm across, with many texts and measurements citing roughly 1.75 mm as the typical average. That makes 1.75 mm the best representative value for a standard, rounded diameter. Values smaller than this (around 1.25 mm or 1.5 mm) are on the low end of normal, while 2.0 mm sits at the higher end; 1.75 mm sits squarely in the common average range used in exams and clinical references. Remember, exact size varies between individuals and measurement methods, but 1.75 mm is a widely accepted standard reference.

The optic disc diameter is the size of the eye’s optic nerve head as seen on fundus examination and imaging. In most adults, the physiological disc measures about 1.5 to 2.0 mm across, with many texts and measurements citing roughly 1.75 mm as the typical average. That makes 1.75 mm the best representative value for a standard, rounded diameter. Values smaller than this (around 1.25 mm or 1.5 mm) are on the low end of normal, while 2.0 mm sits at the higher end; 1.75 mm sits squarely in the common average range used in exams and clinical references. Remember, exact size varies between individuals and measurement methods, but 1.75 mm is a widely accepted standard reference.