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Lecture 2

NROC64H3 Lecture Notes - Lecture 2: Pupillary Light Reflex, Ganglion Cell Layer, Retinitis Pigmentosa

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Matthias Niemeier

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Lecture 2 - vision
Contrast than relative
Light is waves
wavelength, frequency (brightness) and amplitude (color)
Polarity of light Birds use, humans cannot
Three concepts:
refraction (transparent surfaces) - depends on which of the two mediums denser
Anatomy of the eye
Pupil, sclera, Iris, cornea, optic nerve
cornea is important for the focus of light only the cornea cannot change shape (like
the lens) which is also important for focus
Optic disk = blind spot
macula acute (good) vision
fovea best vision here
helpfullness of iris you can tell if the person is looking at you or what they are looking
at (difference between Iris and Sclera)
contraction of the ciliary fibers stretches the lens flat
pressure of vitreous humor gives the eye round shape
Eye disorders
Strabism: one eye becomes weak and affects oculomotor so you have double vision
so you pick one eye causing oculardominance and eventually that becomes blind (the
week eye) (cross eyes)
Cataracts - clouding of the lens needs to replace the lens (artificial lens)
Glaucoma the vitreus pressure if there is too much then you get glacoma and this is
usually in the blind spot so usually don't even notice
Detached retina - the retina detaches from the back of the eye- this can be lasered
back to the eye
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Retinitis pigmentosa - hereditary autoimmune disease where the body attacks the
area right around the retina so you lose your sight starting with night vision.
Spatial vision
-Light that comes from a single source comes and collects at the cornea and then
refracts the light
The cornea cannot change shape but the lens can
When the cilliary fibres relax, the lens stretches and thinner for far images
When the ciliary fibers contract, the lens relaxes (back to regular form) and thicker for
images closer.
Vision correction
Emmetropia normal
astigmatism Cornia not being completely properly structured - not spherical
The pupillary light reflex
the smaller the pupil, the more focused the vision is
the pupil controls the level of light going into the eye
consensual both pupils should construct/relax at the same time If the pupils are not
consensual, it is a find that something is not right in the brainstem
The visual field
Visual acuity: the minimum distance between two dots that you can still see both dots.
Anatomy of the retina
Vertical pathway
photoreceptors bipolar cells ganglion cells
Horizontal pathway
Light enters from the ganglion cell layer and ends at the photoreceptor layer
photoreceptors are special types of neurons
0= the fovea
the blue curve equals count of cones
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