A +4.00D lens decentered 4mm creates how many diopters of induced prism?

• A. 1.0 diopter
• B. 1.6 diopters
• C. 2.0 diopters
• D. 2.5 diopters

Answer: (B)

To determine the amount of induced prism created by a decentered lens, the formula used involves the power of the lens (in diopters) and the amount of decentration (in millimeters). The induced prism (in prism diopters) can be calculated using the formula:

Induced Prism (in prism diopters) = Lens Power (in diopters) x Decentration (in mm).

In this case, you have a lens power of +4.00D and a decentration of 4 mm. Plugging these values into the formula gives:

Induced Prism = 4.00D x 4 mm = 16 prism diopters.

However, when converting millimeters to centimeters for the prism calculation, 4 mm is equivalent to 0.4 cm. The induced prism calculation thus becomes:

Induced Prism = 4.00D x 0.4 cm = 1.6 prism diopters.

This means that the correct answer is 1.6 diopters of induced prism, making the reasoning behind this calculation essential for understanding the relationship between lens power, decentration, and induced prism.