Senses, Endocrine, Blood, Heart, and Reproductive System Practice Test

The transparent front layer of the eye is the cornea. It serves as the eye’s window, letting light pass through and beginning the focusing process by refracting incoming light. The cornea is clear and lacks blood vessels, relying on the tear film for lubrication and nutrients, while its smooth, curved surface helps bend light toward the lens. The iris is the colored part that adjusts pupil size to control how much light enters. The retina is the light-sensitive layer at the back of the eye that detects image information. The sclera is the tough white outer layer that protects the eye but is not transparent.