The curvature of the cornea can be measured by
**Core Concept**
The curvature of the cornea is a critical parameter in ophthalmology, essential for determining the refractive power of the eye. The cornea's curvature affects the way light enters the eye, influencing vision and potentially contributing to refractive errors.
**Why the Correct Answer is Right**
The correct answer is the keratometer, a specialized instrument used to measure the curvature of the cornea. The keratometer works by projecting a mire (a series of concentric rings) onto the cornea and measuring the reflex from the mire to determine the cornea's radius of curvature. This information is crucial for calculating the cornea's power and refractive error, which guides the selection of corrective lenses or refractive surgery.
**Why Each Wrong Option is Incorrect**
* **Option A:** A tonometer measures intraocular pressure, not corneal curvature. Tonometry is a separate diagnostic tool used to assess the eye's pressure.
* **Option B:** A slit lamp is an essential instrument in ophthalmology, but it is not used to measure corneal curvature. Slit lamps are used to examine the anterior segment of the eye, including the cornea, but they do not measure its curvature.
* **Option D:** An autorefractor measures the refractive error of the eye but does not directly measure corneal curvature. Autorefractors estimate the eye's refractive error based on the way light enters the eye.
**Clinical Pearl / High-Yield Fact**
When using a keratometer, it is essential to ensure the mire is centered on the cornea to obtain accurate measurements. Failing to do so can lead to incorrect calculations of corneal power and potentially inappropriate corrective lenses.
**Correct Answer:** C. Keratometer.