What is the cornea?

The cornea is the transparent anterior portion of the outer coating of the eye. It serves several important functions, including allowing light to enter the eye and providing a protective barrier against dirt, germs, and other particles. The clarity of the cornea is crucial for proper vision, as it helps focus light onto the retina. Its transparency is a unique characteristic that distinguishes the cornea from other parts of the eye, which may not share this quality.

Understanding the function and structure of the cornea is essential, especially in the context of eye health and vision correction procedures. The other options do not accurately describe the cornea: the colored part of the eye refers to the iris, the muscle that controls pupil size is the sphincter muscle, and the layer that contains blood vessels is the choroid. Each of these parts has distinct roles and structures that differentiate them from the cornea.