SPECIAL SENSES:SIGHT

-Ashley Zeledon

-Isabella Restrepo

-Ariel Delgado

-Antony Scanlan

-Ashley Gonzalez

-Carolina Matute

OBJECTIVES

The class will be able to understand different functions of the eye and its structure. As well as things that can change their perspective. (Greatest pun ever)

ESSENTIAL QUESTIONIn your own words, what are the functions of the eye.

BELL-RINGER• Describe what you see in each image:

WHAT IS THE EYE?• The ability to focus an image on the retina depends on the refractive power

of both the cornea and the lens as well as on the shape of the eye globe

• The eye changes its shape through the action of inelastic fibers called zonulas. The lens can be rounded or flat.

• Accommodation when the shape of the lens changes to focus.Visual activity is clarity of vision and it is measured by the ability to discern letters or numbers at a given distance.

• Emmetropia is when the eye focuses on an image correctly.

• Myopia is nearsightedness, it results from an eyeball that is too long, a lens too strong or a cornea that is too curved

• Hyperopia is farsightedness, it results from an eyeball that is too short or a "lazy" lens.

STRUCTURES & FUNCTIONS OF THE EYE

• The Orbit is a bony cavity that contains the eyeball, muscles, nerves and blood vessels, as well as the structures that produce and drain tears.

• The outer covering of the eyeball consists of a relatively tough, white layer called the sclera (white part of the eye) which runs through to the edge of the cornea.

• The conjunctiva covers the moist back surface of the eyelids and eyeballs

• The Cornea: clear, curved layer in front of iris and pupil.• Helps focus light on the retina• After passing through the cornea, light travel through the pupil

• Iris: Circular, colored area of the eyes that surrounds the pupil • Controls the amount of light that enters the eye

STRUCTURES AND FUNCTIONS CONT.

• Retina: Contains the cells that sense light and the blood vessels that nourish them.

• most sensitive part

• Macula • Millions of photo-receptors "cones"

• High density of cones in macula makes the visual image detail • 2 main types of photo-receptors: cones and rods.

• Cones: Responsible for sharp, detailed, central vision and color (clustered in macula)

• Rods: Responsible for night and peripheral vision.

HOW THE EYE SEES?• light reflects off the object you are looking at .

• light rays enter the eye through the cornea at the front of the eye.

• The light passes through watery fluid (aqueous humor), and enters the pupil to reach the lens

• The lens can change in thickness to bend the light, which will focus it onto the retina at the back of the eye.

• On the way to the retina, the light passes through the vitreous humor. The virteous fills the eyeball and helps maintain its round shape.

• The light then reaches the back of the eye and hits the retina. The retina translates the light into electrical impulses which are then carried to the brain by the optic nerve.

• Finally, the visual cortex of the brain intercepts these impulses as what we see.

EYE COLORS & DISEASE• Age related: Condition that affects the center of the retina, called the macula

• Deadliest Eye Diseases• Retinobiastoma: It' s cancer that develops from cells in the retina

• This cancer is most common in children• The goal of treatment is the destruction of the cancer while preserving as much vision in

the eye as possible• often the eye will need to get removed to prevent the tumor from spreading • this disease causes the death of 7,000 children throughout the world each year

• Orbital Cellulitis• infection located to the eye socket • the causes of this infection include trauma to the eye, a sinus infection or infection in a

tooth• Some patients develop brain abscesses, meningitis and increased pressure inside the

brain resulting in the patients death.

EYE COLOR AND DISEASE CONT.

• Ocular Melanoma• Most common primary cancer of the eye• can spread throughout the body and cause death if not treated • it does not cause symptoms when they are small and can often be treated locally

• Color blindness

• Having trouble seeing red, green or blue or a mix of these colors.

• A genetic condition

• Men are more effected with color blindness than women • People usually have 3 types of cone cells in the eye; Color Blindness occurs when one of these cones do not exist or

work correctly

Most Contagious Eye Infection

1. Conjunctivitis • This condition results in an infection of the conjuctive of membrane covering the whites of our eyes • Also known as "pink eye"• Most common symptoms include red, inflammed and watery eyes

FUN FACTS• Certain emotions can change pupil size and eye color.

• Eye color can change with age

• No two people can have the same exact eye color

• Some babies have blush eyes that change overtime because infants have no melanin in their eyes.

• The condition of when two eyes on are a different color is Heterochromia

• Tetris is used to treat lazy eyes

• All babies are color blind when they are born

SOURCES

• http://www.aboutkidshealth.ca/En/HealthAZ/HealthandWellness/EyeandEarCare/Pages/Eye-anatomy-and-function.aspx

www.livestrong.com

•www.bitrebels.com

•www.sightsavers.net

•www.alterni.com

www.webmd.com