In the Reduced Eye model, what is the cornea to posterior focal point distance?

In the Reduced Eye model, what is the cornea to posterior focal point distance?

• A. 22.22 mm
• B. 25.0 mm
• C. 20.0 mm
• D. 19.5 mm

Answer: (A)

In the reduced eye model, all optical power is distilled into a single refracting surface at the cornea, and distant objects are brought to focus on a fixed plane behind that surface—the posterior focal point. That back focal length is about 22.22 mm, meaning the cornea to posterior focal point distance is 22.22 mm. This standard value is used in paraxial calculations to place the retina (the image plane) at a convenient, fixed distance in the simplified geometry of emmetropia. So the cornea-to-posterior focal point distance is 22.22 mm.

In the reduced eye model, all optical power is distilled into a single refracting surface at the cornea, and distant objects are brought to focus on a fixed plane behind that surface—the posterior focal point. That back focal length is about 22.22 mm, meaning the cornea to posterior focal point distance is 22.22 mm. This standard value is used in paraxial calculations to place the retina (the image plane) at a convenient, fixed distance in the simplified geometry of emmetropia. So the cornea-to-posterior focal point distance is 22.22 mm.