The Eye Flashcards
What is the SCLERA?
The tough, supporting wall of eye
What is the CORNEA?
The transparent outer layer found at the front of the eye. It refracts and bends the light
What is the IRIS?
Contains the muscles that allow it o control the diameter of the pupil and therefore how much light enters the eye
What does the LENS do ?
focuses the light on to the RETINA
What does the retina contain?
Receptor cells sensitive to light intensity and colour
What controls the shape of the lens?
CILIARY MUSCLES and SUSPENSORY LIGAMENTS
What does the OPTIC NERVE do ??
Carries impulses from receptors on the retina to the brain
What’s a reflex in the eye ?
- The pupil is made smaller in bright light, so the amount of light let it is reduced
- the pupil is made bigger in dim light to increase the amount of light
What can damage the RETINA ?
Bright light
What is accommodation??
When the eye focuses light on the retina by changing shape of the lens
What controls the size of the pupil?
- The circular muscles in the IRIS
* radial muscles
How does the eye focus on near objects?
The ciliary muscles contract
Which slackens the suspensory ligaments
The lens becomes fat
This increased the amount of light it refracts
How does the eye focus on distant objects ?
The ciliary muscles relax
Which allows the suspensory libaments to pull tight
This makes the lens go thin
So it refract light by a smaller amount
Why re people long sited ?
- The lens is the wrong shape and doesn’t refract the light enough
- The eye ball is too short
Why are people short sited?
- the lens is the wrong shape and refracts the light too much
- the eyeball is too long
What lens is used for longsightedness people?
Convex
Lens that curves outwards
What lens is used for short sided people ?
Concave
A lens that curves inwards
What are convex lenses used for ? And what do they do ?
Longsired people
Increase refraction
What are concave lenses used for? And what do they do ?
Short sited people
Reduce refraction
Give the treatments for vision defects
- contact lenses
- laser eye surgery
- replacement lens surgery
Advantages of contact lenses
- lightweight
- invisible
- convenient for sports
What is the name given to the transparent layer at the front on the eye?
Cornea
What is the scientific word for short sited people ?
Myopia
What is the scientific term for Long sited people?
Hyperopia
