ABO NOCE Practice Test

What is the tolerance for axis power based on cylinder power of 0-0.25?

1. 10°

2. 14°

3. 20°

4. 25°

The correct answer is: 14°

When examining the tolerance for axis power based on a cylinder power of 0-0.25, the accepted standard is determined by the spherical power and the resultant visual acuity needed for effective correction. Generally, for low cylinder powers, the axis tolerance is set to accommodate minor deviations that may occur during refraction or lens fitting. For a cylinder power of 0-0.25, the standard axis tolerance is typically around 14 degrees. This means that any measurement within 14 degrees from the prescribed axis can still be considered acceptable for maintaining optimal vision correction and ensuring that the patient experiences minimal visual distortion. Understanding this tolerance is critical in clinical practice, as even slight variations in axis can affect how well the prescribed lenses perform for the patient. A tolerance of 14 degrees allows for practical flexibility without significantly compromising visual acuity.