The Eye: Structure

The Eye Structure External Parts of the Eye

(Tear Duct)

1. Sclera White part of the eyeIs made of tough tissueProtects the inner workings of the eye and gives the eye its shape

2. Cornea The curved, clear, outer surface Covers the iris and pupil

3. Aqueous HumorA clear, watery fluid Circulates in the front part of the eye, maintaining a constant pressure inside the eye.

4. Pupil Is the opening in the center of the irisThe size of the pupil:determines the amount of light entering the eyecontrolled by circular muscles

5. IrisThe colored part of the eyeMade of circular musclesControls the size of the pupil

6. Lens A clear convex lensIs responsible for focusing light to form an image on the retinaCan change shape to focus on nearby and distant objects

7. Vitreous HumorA clear, jelly-like substance Fills the eye behind the lensHolds the structures of the eye in placeMaintains the shape of the eye

8. Optic Nerve

A thick bundle made of millions of neurons Carries visual information from the retina to the brain. 9. Retina

A thin, translucent, light-sensitive tissue made of specialized cells called rods and conesReceives images formed by the lens 10. Optic Disc

The point where the optic nerve enters the retina NOT sensitive to light Known as the blind spot 11. Tapetum A shiny layer that lines the area behind the retina of many animals Helps make animal eyes visible in the darkAllows them to see better at night

Vision

Corrective Lenses (Glasses & Contacts) Near Sighted

Far Sighted

Color Blindness Your eyes have special cells called rods and cones

Rods Light sensitiveCones Color Sensitive

Color Blindness There are three main kinds of color vision defects. Red-green color vision defects are the most common. This type occurs in men more than in women. The other major types are blue-yellow color vision defects and a complete absence of color vision.

Color Blindness Most of the time, color blindness is genetic. There is no treatment, but most people adjust and the condition doesn't limit their activities.

LASIK 1. Create a flap of corneal tissue2. Remodel the cornea using the laser3. Reposition the flap