Anatomy and Function of the Human Eye

The Human Eye

• The eye is responsible for vision.
• The eye contains specialized receptor cells called photoreceptors.
• Photoreceptors detect light and convert it into electrical signals that are sent to the brain.
• These electrical signals from the photoreceptors are interpreted by the brain as images.

Parts of the Eye

• The eye is made up of several different parts, each serving a specific function.
• The cornea is the transparent outer layer of the eye. It helps to focus light entering the eye.
• The iris is the colored part of the eye. It controls the amount of light that enters the eye by adjusting the size of the pupil.
• The pupil is the black hole in the center of the iris.
• The lens is a transparent, flexible structure that further focuses light onto the retina.
• The retina is the light-sensitive inner layer of the eye. It contains photoreceptor cells that detect light and convert it into electrical signals.

Functions of the Eye

• The eye works with the brain to create a sense of vision.
• The photoreceptor cells in the retina are responsible for detecting light and converting it into electrical signals.
• These electrical signals are sent to the brain via the optic nerve.
• The brain interprets these signals and creates a visual image.

Visual Defects

• Myopia (nearsightedness) is when a person can see things that are close up clearly, but not things that are far away. This is due to the eyeball being too long.
• Hypermetropia (farsightedness) is when a person can see things that are far away clearly, but not things that are close up. This is due to the eyeball being too short.
• Cataract is a clouding of the eye's natural lens. This clouding can make vision blurry, hazy, or dim.
• A cataract can be surgically removed.
• Accommodation is the ability of the eye to focus on objects at different distances.
• The ciliary muscles help the eye to accommodate by adjusting the shape of the lens.
• The ciliary body is a ring of muscle tissue that helps to control the shape of the lens.
• The aqueous humour is a clear fluid that fills the space between the cornea and the lens.
• The vitreous humour is a clear gel that fills the space between the lens and the retina.
• The conjunctiva is a thin membrane that covers the white part of the eye. It protects the eye from infection.
• The choroid is a layer of tissue that supplies blood and nutrients to the inner eye. It is located between the retina and the sclera.

The Retina

• The retina is the light-sensitive inner layer of the eye.
• The retina contains two types of photoreceptor cells: rods and cones.
• Rods are more sensitive to light than cones and are responsible for vision in dim light.
• Cones are responsible for color vision and vision in bright light.
• The macula is a small, central area of the retina that is responsible for sharp central vision.
• The fovea is the center of the macula and is responsible for the sharpest vision.
• The optic nerve transmits signals from the retina to the brain.
• The point where the optic nerve leaves the retina is called the optic disc.
• There are no photoreceptor cells at the optic disc, creating a blind spot in each eye.