Certified Ophthalmic Assistant Practice Exam

What is the spherical equivalent of +2.00 +5.00 X 180?

1. +3.50

2. +4.50

3. +5.00

4. +2.00

The correct answer is: +4.50

To determine the spherical equivalent of a given prescription, you need to focus on converting the cylindrical component into its spherical equivalent, as the spherical equivalent is a simplified way to represent the total refractive power of the lens. In this case, the prescription is +2.00 +5.00 X 180. This means there is a sphere of +2.00 diopters and a cylinder of +5.00 diopters axis at 180 degrees. To calculate the spherical equivalent, you take half of the cylinder's power and add it to the sphere's power. So for a cylinder of +5.00, half is +2.50. Now, you add this +2.50 to the +2.00 spherical component: +2.00 (sphere) + +2.50 (half of the cylinder) = +4.50. Thus, the spherical equivalent for the prescription is +4.50. This is why that option is the correct choice, as it accurately reflects the total refractive power when considering both the spherical and cylindrical components.