**Core Concept**
Autorefractometry is a non-invasive, objective method of measuring the refractive error of the eye, used to determine the power of the cornea and the crystalline lens. It is a crucial diagnostic tool in ophthalmology and optometry for assessing the need for corrective lenses, such as glasses or contact lenses.

**Why the Correct Answer is Right**
Autorefractometry uses a combination of light and optical principles to measure the refractive error of the eye. The device emits a beam of light through the pupil and measures the amount of deflection or refraction that occurs as it passes through the eye. This information is then used to calculate the power of the cornea and the crystalline lens, providing an accurate measurement of the refractive error. The autorefractor takes into account the spherical (near/far) and cylindrical (astigmatism) components of the refractive error.

**Why Each Wrong Option is Incorrect**
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* **Option D:** (not provided) - This option is not available as the correct answer is not provided.

**Clinical Pearl / High-Yield Fact**
Autorefractometry is a quick and painless procedure that can be used on patients of all ages, from children to adults. However, it may not be as accurate in patients with certain eye conditions, such as cataracts or corneal irregularities.

**Correct Answer:**
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