What instrument eliminates peripheral rays of light and allows only central light rays to pass through?

The instrument that eliminates peripheral rays of light and allows only central light rays to pass through is a pinhole. The pinhole is designed to create an optical effect by limiting the amount of light that enters the eye, focusing only on the central rays. This helps in assessing visual acuity and can assist in diagnosing refractive errors by providing a clearer image of the object being viewed.

In contrast, the slit lamp is used for a detailed examination of the anterior and posterior segments of the eye with the help of a slit beam of light. While it provides extensive illumination and magnification, it does not function to filter out peripheral rays in the same way a pinhole does.

The ophthalmoscope is instrumental in viewing the interior structures of the eye, specifically the retina, but it does not serve the purpose of excluding peripheral light.

The goniolens is used during gonioscopy to examine the anterior chamber angle and does not act to isolate central light rays in the manner of a pinhole. Each of these instruments has a specific use in ophthalmology, but the pinhole's unique design specifically targets the centralization of light rays, making it the correct choice in this scenario.