In the Reduced Eye model, what is the cornea to anterior focal point distance according to Knapp's law?

In the Reduced Eye model, what is the cornea to anterior focal point distance according to Knapp's law?

• A. 16.67 mm
• B. 20.00 mm
• C. 12.50 mm
• D. 18.00 mm

Answer: (A)

In the reduced eye, Knapp's law uses the eye’s total optical power to set where the anterior focal point lies from the cornea. The reduced eye is modeled with a total power of about 60 diopters, so the focal length is f = 1/P = 1/60 meters ≈ 0.0167 meters, which is 16.7 mm. That is the distance from the cornea to the anterior focal point where parallel rays would first come to a focus. Therefore, about 16.7 mm is the correct distance. The other numbers would imply different overall powers for the reduced-eye model, not the standard 60 D used in Knapp’s law.

In the reduced eye, Knapp's law uses the eye’s total optical power to set where the anterior focal point lies from the cornea. The reduced eye is modeled with a total power of about 60 diopters, so the focal length is f = 1/P = 1/60 meters ≈ 0.0167 meters, which is 16.7 mm. That is the distance from the cornea to the anterior focal point where parallel rays would first come to a focus. Therefore, about 16.7 mm is the correct distance. The other numbers would imply different overall powers for the reduced-eye model, not the standard 60 D used in Knapp’s law.