Unit 3 - The eye Flashcards
What is the cornea
- The hard outside surface
- Protects the eye
- Refracts light
- Convex shape
- High refractive index
The Iris
Controls the amout of light that enters the eye (dialates and contracts)
The pupil
Where light enters
The lens (also how its connected)
The lens focus’ light
Connected to the ciliary muscles by the suspensory ligaments
What do the ciliary muscles do
Changes the shape of the lens and the focal length
What happens when the Ciliary muscles contract
Tension is released and the lens turns into a more spherical shape
What happens when the Ciliary uscles relax
The suspensory ligaments pull the lens into a thinner, flatter shape
The retina
Images are formed here (its covered in light sensitive cells - these detect light and send signals to the brain to be interpreted)
The Optic Nerve
Sends electrical signals to the brain
What is the Sclera?
White and opaque to prevent light entering the eye
The near point
The closest point at which an object can be seen clearly
The farpoint
The furthest than an object can be seen clearly
What is long sightedness?
When someone can’t focus clearly on close object because the image is formed behind the retina
What are some reasons for long sightedness
- Lens is too weak
- Cornea may be too flat
- Eyeball may be too short
Solutions to long sightedness?
Use a convex lens so rays focus on the retina (to bend the rays more)
