The eye Flashcards
What are the main parts of the eye
-s… l…. -r
-o… n…
-s…
-c… m…
-l…. -p…
-c…. -i…
-suspensory ligaments
-retina
-optic nerve
-sclera
-ciliary muscle
-lens
-pupil
-cornea
-iris
What’s does the sclera do
-it is t…
-it is a s…. wall of the …
-it is tough
-it is a supporting wall of the eye
What does the cornea do
-is the t… outer layer at the … of the eye
-it r… light into the eye
-is the transparent outer layer at the front of the eye
-it refracts light into the eye
What does the iris do
-contains m… that allow it to control the d… of the p… affecting how much l… enters the eye
-contains muscles that allow it to control the diameter of the pupil affecting how much light enters the eye
What does the lens do
-focuses … onto the …
-focuses light onto the retina
What does the retina do
-contains r… cells sensitive to l… intensity and c…
-contains receptor cells sensitive to light intensity and colour
How is the shape of the lens controlled
By c… m… and s… l…
By ciliary muscles and suspensory ligaments
What does the optic nerve do
-carries i… from the r… on the retina to the b…
-carries impulses from the receptors on the retina to the brain
Why does the iris have a reflex
Very bright … can damage the r…
Very bright light can damage the retina
When and how does the pupil become smaller
-light r… detect a bright light
-a r… is triggered that makes the c… muscles c… and r… muscles …
- this makes the … smaller, reducing the amount of … that can enter the eye
-light receptors detect a bright light
-a reflex is triggered that makes the circular muscles contract and radial muscles relax
- this makes the pupil smaller, reducing the amount of light that can enter the eye
When and how does the pupil become smaller
-light … detect d… light
-a reflex is triggered that makes the c… muscles … and the r… muscles …
-this makes the pupil …, I… the amount of light that can enter the …
-light receptors detect dim light
-a reflex is triggered that makes the circular muscles relax and the radial muscles contract
-this makes the pupil bigger, increasing the amount of light that can enter the eye
When do circular muscles relax and radial muscles contract
When in dim lighting
When do circular muscles contract and radial muscles relax
In bright light
How does the eye focus on the retina
By changing the shape of the lens
How does the eye look at near objects
-c… muscles …, and the s… ligaments slacken
-the lens becomes t… and more c…
-this increases the amount that light is …
-ciliary muscles contract, and the suspensory ligaments slacken
-the lens becomes thicker and more curved
-this increases the amount that light is refracted
How does the eye look at distant objects
-the … muscles relax, and the … ligaments …
-the lens becomes … and … curved
-this … the amount that … is refracted
-the ciliary muscles relax, and the suspensory ligaments tighten
-the lens becomes thinner and less curved
-this decreases the amount that light is refracted
Why does eye sight get poorer as you get older
-Your eyes l… loses f… so it can’t easily spring back to its s…
-meaning … can’t be focused well for … viewing
-Your eyes lens loses flexibility so it can’t easily spring back to its shape
-meaning light can’t be focused well for near viewing
What are long sighted people unable to focus on
Near objects
What are short sighted people unable to focus on
Far away objects
What happens when you are long sighted
-your … is the wrong … and d… refract the light e… or the … is too …
-the i… of near objects focus … the …
-… lenses are used to fix it
- the medical term is …
-your lens is the wrong shape and doesnt refract the light enough or the eyeball is too short
-the images of near objects focus behind the retina
-convex lenses are used to fix it
- the medical term is hyperopia
What happens when you are short sighted
-when your … is the wrong … and … light too … or the … is too …
-the images of … objects focus … of the …
-… lenses are used to fix this
-medical term is …
-when your lens is the wrong shape and refracts light too much or the eyeball is too long
-the images of distant objects focus infront of the retina
-concave lenses are used to fix this
-medical term is myopia
What lenses are used to fix short sightedness and long sightedness
Concave lens
Convex lens
Treatments for visions defects
-g
-c… l…
-l… e… s…
-r… l… s…
-glasses
-contact lenses
-laser eye surgery
-replacement lens surgery
How do contact lenses work
-they are … lenses that sit on the … of your …
-are shaped to compensate for the f… in focusing
-more convenient than …
-… types of … lenses … and … lenses
-they are thin lenses that sit on the surface of your eye
-are shaped to compensate for the fault in focusing
-more convenient than glasses
-2 types of contact lenses hard and soft lenses
What are the 2 types of contact lenses and what is the difference
… lenses and … lenses
… lenses are more …, but carry a higher … to eye … than … lenses
Soft lenses and hard lenses
Soft lenses are more comfortable, but carry a higher risk to eye infections than hard lenses
How does laser eye surgery work
-a … is used to … tissue changing the … of the … which changes how … light is … onto the …
-s… it down improves … sight
-changing the … to make it more p… improves … sight
-there are … as it is a … such as … or worsening eye sight
-a laser is used to vaporise tissue changing the shape of the cornea which changes how strongly light is refracted onto the retina
-slimming it down improves short sight
-changing the shape to make it more powerful improves long sight
-there are risks as it is a surgery such as infection or worsening eye sight
How does replacement lens surgery work
-… sightedness can be more e… treated by r… the …
-The … lens is removed and an … lens made of … is inserted in its place
-there are higher … as it could damage the …
-short sightedness can be more effectively treated by replacing the lens
-The natural lens is removed and an artificial lens made of plastic is inserted in its place
-there are higher risks as it could damage the retina
