ABO NOCE Practice Test

What percentage of cylinder power is based on the axis of 30?

1. 50%

2. 25%

3. 75%

4. 100%

The correct answer is: 25%

In ophthalmic optics, the percentage of cylinder power that is based on the axis indicates how much of the total astigmatism correction is effective at a specific axis. When we refer to an axis of 30 degrees, we consider how the cylinder power interacts with the meridians. The powers in different meridians can be conceptualized in relation to a 90-degree span. In an astigmatic lens, the total cylindrical power is usually divided between the two principal meridians, which are perpendicular to each other. At the axis of 30 degrees, we can calculate the effective power in that direction. The effective cylinder power at any given axis can be determined by decomposing the total cylinder power into its components. For an axis of 30 degrees, the effective power can typically be found by applying trigonometric functions. In the case of 30 degrees, the projection of the cylinder's power can be quantitatively expressed by the cosine of the angle. Due to the nature of angles in relation to cylindrical power, the effective power at 30 degrees is about 25% of the total cylinder power. This reflects the relationship of the cylinder's effect directly along that particular axis. Therefore, the percentage of cylinder power based on