Problem 1: The eye Flashcards
Which layer is the sclera and what is its function?
the protective outer layer of the eye
Which layer of the eye is the choroid and what is its function
the choroid is the middle layer and its function is providing the eye with oxygen and nutrients
Cornea
part of outer layer that is in front of pupil, already bends light but cannot adjust the amount of refraction
what is the optic axis
where the retinal image is focussed
lens
just behind the iris, refracts light passing thought the eye so it focusses on the retina properly
what is accomodation
the ciliary muscles change the shape of the lens to enable you to see objects in all distances sharply (ciliary muscles pull on the lens make it thicker (closer objects) and relax to make the lens flatter (objects further away)
what are the three chambers in the eye and what liquids are in there, what is the function of the liquid
the anterior chamber and the posterior chamber (filled with aqueous humor) and the vitreous chamber filled with vitreous humour. The function of the liquid is to keep de shape of the eye stable, so that it doesn’t collapse from air pressure
what are the different pathways from the retina to the optic nerve and what cells do they contain
horisontal pathway: horizontal and amacrine cells (provide feedback to the photoreceptors)
vertical pathway: first cones and rods, then the bipolar cells and then the retinal ganglion cells
pigment epithelium
the layer that connects the rods and cones to the choroid
how how are rods and cones distributed across the retina?
near fovea/yellow spot: only cones
peripheral are: rods and cones (however there are more cones than rods)
blind spot/optic disk: where the optic nerve connects to the eye, there are no photoreceptors
what happens in near or farsightedness?
the focal point is not on the retina but behind or in front of it
astigmatism:
the corona is not spherical, so some lights bend in front of the retina and some behind
what is (& cause of) presbyopia
lens of the eye becomes less flexible over time, old age, not being able to read or do stuf that is closeby
myopia:
nearsightedness (image is formed in front of retina, near objects will be best in focus)
Hyperopia:
eye is too short for optics –> blurry image, for this eye it’s best that the image lies behind the retina so it’s far signtedness
Night blindness:
no rods –> no vision at night
day blindness:
no cones, normal levels of light are painful and there’s a loss of colour vision
Macular degeneration:
condition that destroys fovea (cones) –> creates a blind sport covering central vision/fovea
cataract:
lens loses transparency, causes distorted images and a foggy lens
optic nerve damage:
fluid in the eye is not able to drain anymore, so pressure becomes too high and starts to push against optic nerve –> damage
what is lateral inhibition + which illusions
when an excited neuron reduces inhibition in its neighbours who are less excited. the horizontal cell causes average inhibition + mach bands + Herman grind (squares in squares)
edge detection
without lateral inhibition we wouldn’t be able to detect edges
