Which statement is true about axis and cylinder in minus cylinder notation?

Which statement is true about axis and cylinder in minus cylinder notation?

• A. The axis marks the meridian with the least power
• B. The sphere power defines the axis
• C. The cylinder value defines axis orientation
• D. The axis has no relation to power

Answer: (A)

In minus cylinder notation, the axis marks the meridian with the least refractive power. The cylinder value tells you how much power is added in the meridian 90 degrees away from that axis; since the cylinder is negative, that perpendicular meridian ends up with more myopic power than the axis meridian. Put simply, the axis is the orientation where the cylinder has zero power, so it represents the meridian with the least power, while the cylinder quantity defines the difference between the two principal meridians. Sphere power sets the overall baseline, but it does not define the axis itself.

In minus cylinder notation, the axis marks the meridian with the least refractive power. The cylinder value tells you how much power is added in the meridian 90 degrees away from that axis; since the cylinder is negative, that perpendicular meridian ends up with more myopic power than the axis meridian. Put simply, the axis is the orientation where the cylinder has zero power, so it represents the meridian with the least power, while the cylinder quantity defines the difference between the two principal meridians. Sphere power sets the overall baseline, but it does not define the axis itself.