Layers of the eye Flashcards
CONJUCTIVA
The conjunctiva is the membrane covering the sclera. The conjunctiva also covers the interior of your eyelids
SCLERA
The sclera is sometimes known as the “whites” of the eye. It covers more than 80% of the eyeball’s surface.
On the exterior, the sclera is smooth and white, but on the inside, it is brown and has grooves that help in the proper attachment of the eye tendons. Tendons are strong, flexible tissues that join muscles to structure, such as bones and, in this case, the sclera.
EPISCLERA
The episclera is a thin layer of tissue that lies on top of the sclera. The episclera has tiny blood vessels that supply the sclera with nutrients.
IRIS
The iris is the coloured part of the eye and is unique to each person. This structure is located in the front of the eye, between the cornea on the outside and the lens on the inside.
The iris primarily regulates how much light reaches the retina by controlling the size of the eye’s “window,” or pupil.
PUPILS
The pupil is seen as a black dot in the center of the iris.
The pupil is essentially a hole that allows the eye to focus on the things in front of it. They open and close to regulate the amount of light that enters the eye.
CORNEA
The cornea is the clear and protective outer layer of your eye. Together with the sclera (the white of your eye), the cornea acts as a barrier against dirt, infectious microorganisms, and other substances that can damage the eye.
In addition to protection, the cornea also plays a significant role in vision. Considering the dome shaped surface of the cornea, this structure refracts (bends) light as it passes through the eye. This enables it to focus on objects effectively.
UVEA
The uvea is the eye’s middle layer. It is located underneath the white part of the eye (the sclera) and is composed of three parts:
The iris
Ciliary body
Choroid
These structures control some eye functions, such as adapting to varying levels of light or object distances.
CHOROID
This vascular layer is located between the sclera and retina of your eye. It delivers nourishment (through blood and oxygen supply) to the retina’s outer layers.
In short, the choroid is the source of life that keeps the retina functioning effectively.
The choroid reflects light, which causes the red-eye effect in photographs.
RETINA
The retina is a sensitive membrane that covers your eye’s rear surface. Images are transmitted to the retina when your eye picks up the images.
The retina converts these images into impulses, which are sent to your brain through the optic nerve. This enables you to see and interpret what you see
AQUEOUS HUMOR
Aqueous humor is a fluid substance that fills the eye. It’s divided into two chambers. The anterior chamber is situated in front of the iris, whereas the posterior chamber is situated right behind it.
CILIARY BODY
The ciliary body is a ring-shaped tissue found behind the iris. It attaches to the lens through the zonular fibers (fibers of Zinn).
The ciliary body holds and regulates the movement of the eye lens, hence keeping the lens shape intact.
OPTIC NERVE
The optic nerve is a bundle of about 1.2 million nerve fibres that transmit visual information to the central nervous system (brain).
There is one nerve per eye connecting each eye to the brain. Vision loss may occur if any of the nerves is damaged
OPTIC DISC
The optic disc is the place at which the axons of retinal ganglion cells join together and mark the beginning of the optic nerve (second cranial nerve).
The optic disc also serves as the entrance site for major blood vessels that nourish the retina.
FOVEA CENTRALIS
The fovea Centralis (central fovea) is a tiny depression in the retina that houses cones that help with proper vision. It is located within the macula
LENS OF EYE
The lens of the eye (or crystalline lens) is the transparent lentil-shaped structure inside your eye. This is the natural lens.
It is located behind the iris and to the front of the vitreous humor (vitreous body).
