## **Core Concept**
The power of the normal eye refers to its refractive power, which is measured in diopters (D). The eye's ability to focus light onto the retina is determined by the combined refractive powers of the cornea, lens, and the length of the eyeball. A normal eye has a specific range of refractive power that allows clear vision at a standard distance.

## **Why the Correct Answer is Right**
The correct answer, , corresponds to the generally accepted value for the power of a normal eye. This value represents the total refractive power needed for an emmetropic eye (an eye with normal vision) to focus parallel light rays directly onto the retina. The total power of the eye is approximately 60 diopters, with the cornea contributing about 40-45 diopters and the lens contributing about 10-15 diopters, but these values can vary slightly.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This value underestimates the total refractive power of the eye. While the lens itself has a power of around 10-15 diopters, the total power of the eye is significantly higher due to the combined effect of the cornea and lens.
- **Option B:** This option might seem plausible but does not accurately represent the total power of the eye. The power of the eye is not just the power of the lens; it's the combined refractive power of all components.
- **Option D:** This value overestimates the total refractive power of a normal eye. While high refractive powers are seen in conditions like myopia or with certain corrective lenses, a normal eye does not have this level of refractive power.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the total refractive power of the human eye is approximately , which allows for clear vision of distant objects without accommodation. This value can vary slightly among individuals but serves as a standard reference point in ophthalmology and optometry.

## **Correct Answer:** .