What is the equation for Far Point as given in the material?

What is the equation for Far Point as given in the material?

• A. FP = 1/RE
• B. FP = RE
• C. FP = 1/DE
• D. FP = RE^2

Answer: (A)

The main idea is how far point distance relates to the eye’s refractive power. Refractive power, measured in diopters, is the reciprocal of focal length (P = 1/f, with f in meters). The far point is the distance from the eye at which a distant (parallel) ray would be focused on the retina without any accommodation. Since the far point distance corresponds directly to the eye’s optical power, FP = 1/RE, with FP in meters and RE in diopters. For example, if the refractive error is -3 diopters (myopia), the far point is 1/3 of a meter in front of the eye. If RE is 0 (emmetropia), the far point is effectively at infinity, consistent with distant objects focusing on the retina without accommodation.

The main idea is how far point distance relates to the eye’s refractive power. Refractive power, measured in diopters, is the reciprocal of focal length (P = 1/f, with f in meters). The far point is the distance from the eye at which a distant (parallel) ray would be focused on the retina without any accommodation. Since the far point distance corresponds directly to the eye’s optical power, FP = 1/RE, with FP in meters and RE in diopters.

For example, if the refractive error is -3 diopters (myopia), the far point is 1/3 of a meter in front of the eye. If RE is 0 (emmetropia), the far point is effectively at infinity, consistent with distant objects focusing on the retina without accommodation.