Studied by 0 peopleWhat stimuli are the receptors of the eye sensitive to?
light intensity and color
What are the two main functions of the structures found within the eye?
Focusing on near or distant objects - accommodation.
Adaption to dim light.
Label the parts of the eye.
A - cornea
B - iris
C - ciliary muscles
D - lens
E - suspensory ligaments
F - retina
G - optic nerve
H - sclera
Describe the structure and function of the retina.
A light-sensitive layer found at the back of the eye. Light stimulates the _______ cells, resulting in the impulses being sent to the brain.
Describe the structure and function of the optic nerve.
Connects the eye and the brain. It carries impulses to the brain so that an image can be visualized.
Describe the structure and function of the sclera.
The tough, outer layer of the eye which protects its internal structures.
Describe the structure and function of the cornea.
The curved transparent layer at the front of the eye. It lets light into the eye and allows light to be focused onto the retina.
Describe the structure and function of the iris.
A muscle which controls the size of the pupil by contracting or relaxing. This allows the eye to adjust to bright and dim lighting.
Describe the structure and function of the ciliary muscles and suspensory ligaments.
They hold the lens in place and control its shape.
Describe how the iris alters the size of the pupil in both bright and dim light.
Bright light: circular muscles contract and radial muscles relax - makes pupil smaller to avoid retinal damage.
Dim light: circular muscles relax and radial muscles contract - makes pupil larger so more light can enter the eye.
What is accommodation?
The alteration of the lens’ shape in order to focus on near or distant objects.
How does the eye focus on a nearby object?
Ciliary muscles contract.
Suspensory ligaments loosen.
Lens becomes thicker and more curved - light rays are refracted strongly.
How does the eye focus on a far away object?
Ciliary muscles relax.
Suspensory ligaments tighten.
Lens becomes thinner - light rays are refracted weakly.
What is myopia?
(Short-sightedness) Usually occurs when the lens of the eye is too curved. As a result, light is focused in the front of the retina so images appear blurry.
How can myopia be treated?
Using glasses with a concave lens, which spreads out light rays so they can be focused on the retina.
What is hyperopia?
(Long-sightedness) Usually occurs when the lens of the eye is too flat. As a result, light is focused behind the retina so images appear out of focus.
How can hyperopia be treated?
Using glasses with a convex lens, which brings the light rays together so they can be focused on the retina.
What are contact lenses?
Lenses that are placed on the eye.
What are the two types of contact lenses?
Hard - rigid material, last a long time, must be kept sterile.
Soft - flexible material, last for a shorter time, more comfortable.
What is laser eye surgery?
The use of lasers to fix visual defects in adults.
How is laser eye surgery used to treat myopia?
Lasers reduce the thickness of the cornea so light is refracted less strongly.
How is laser eye surgery used to treat hyperopia?
Lasers alter the curvature of the cornea so that light is refracted correctly.
How can replacement lenses be used to treat visual defects?
Can either be implanted into the eye (along with natural lens) or it may replace the natural lens altogether.
What are the risks of lens replacement?
Retinal damage, cataracts, and infections.
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