Iris
The iris, known in English as the Iris, is a crucial component of the outer eye. Its primary function is to regulate the size of the dark circular opening at the center of the eye, known as the pupil. By altering the shape of the pupil, the iris controls the amount of light that enters the eye, utilizing the muscles it contains. Additionally, the color of a person’s eyes is determined by the color of their iris; for instance, if someone has a blue iris, their eyes will appear blue.
Pupil
The Pupil is another essential part of the outer eye, characterized by a dark circle located at the center of the iris. It plays a vital role in controlling the amount of light that enters the eye. To observe how the pupil responds to varying lighting conditions, you can use a flashlight. When illuminated from nearby, the pupil constricts, becoming smaller; conversely, when the light is removed, the pupil dilates, increasing in size.
Cornea
The Cornea is one of the most visible components of the outer eye, providing a dome-like shape to its exterior. It covers both the pupil and the iris and is crucial for focusing light onto the retina, contributing approximately 66% of the eye’s total optical power.
Sclera
The Sclera refers to the white outer covering of the eye. It is composed of tough tissue that envelops the eyeball and features tiny pinkish lines that may be observed with close inspection, which are actually blood vessels and capillaries that supply the sclera with blood.
Conjunctiva
The Conjunctiva is another external component of the eye, represented as a membrane that covers the outer surface of the eye and the inner surface of the eyelids. The conjunctiva is essential for secreting mucous and tears, which protect the eyes from bacterial infections. Notably, the conjunctiva does not cover the cornea.