Kaplan Nursing Entrance Practice Exam

What is the primary function of the cornea in the eye?

1. Controls pupil diameter

2. Coordinates muscle movement

3. Bends and focuses light rays

4. Detects carbon dioxide levels

The correct answer is: Bends and focuses light rays

The primary function of the cornea is to bend and focus light rays that enter the eye. Located at the front of the eye, the cornea is a transparent, dome-shaped structure that plays a crucial role in vision. When light passes through the cornea, it is refracted, helping to direct the light onto the retina at the back of the eye. This process is essential for clear vision because the cornea provides a significant portion of the eye's total optical power. Other options listed relate to different structures or functions within the eye or body. For instance, controlling pupil diameter is primarily the function of the iris, which adjusts the size of the pupil to regulate the amount of light entering the eye. Muscle coordination is associated with other muscles and systems, not specifically the cornea. Lastly, the detection of carbon dioxide levels involves specialized chemoreceptors in the body, not a function of the cornea. Understanding the specific role of the cornea helps highlight its importance in the visual process.