Which instrument is used to obtain information about the cornea and surrounding structures?

The slit lamp is the correct choice because it is a specialized instrument designed to provide a detailed, magnified view of the cornea and surrounding structures of the eye. It utilizes a combination of bright illumination and a high-powered microscope to examine the anterior segment, which includes the cornea, iris, and lens. The slit lamp allows for a thorough assessment of the cornea's surface, curvature, and any potential abnormalities or diseases, making it an essential tool for eye care professionals.

Other instruments, while useful for other specific measurements or assessments, do not provide the same level of detail or comprehensive view of the cornea. The radius scope, for example, is primarily used to measure the curvature of the cornea but does not allow for a detailed examination of its overall health or the surrounding structures. The corneascope is not a standard term in ophthalmology; it may refer to instruments that assess corneal topography, but it lacks the versatility of the slit lamp. A keratometer is focused on measuring the curvature of the cornea specifically, primarily for fitting contact lenses, rather than providing an overall examination of the cornea and adjacent structures.