NEURO 3000 MD 4 EXAM QUESTIONS WITH
ACCURATE ANSWERS
Vision overview - ANSWER - Human vision is highly advanced relative to other animals
- One can think of the eye as having two functions:
* A camera-like system to focus light on the back of the eye (retina)
* The generation of a pattern of action potentials from the input of many photons
(quantum of light or other electromagnetic radiation) hitting photoreceptors (light
energy converted to electrical/ chemical energy)
- Our visual system detects differences in light intensity hitting different parts of the
retina
- Information gathered in the retina is sent to the primary visual cortex, but also to other
areas of the brain that influence biological rhythm, eye movement, control of the
pupillary light reflex, and shape of the lens
- All the complex data we need to construct our perception of the world is gathered by
the retina (kind of like a detector organ)
Properties of light (pt. 1) - ANSWER - Light: Electromagnetic radiation within the portion
of the electromagnetic spectrum that is perceived by the human eye (400-700 nm)
- Frequency: Waves per second (higher frequency = higher energy)
- Wavelength: Distance between peaks (determines frequency, and thus energy);
smaller wavelength = higher frequency
- Amplitude: Peak minus trough (how bright light is)
Properties of light (pt. 2) - ANSWER - Optics: The study of light and rays and their
interactions
- Light rays travel in straight lines until they interact with the atoms and molecules of the
atmosphere and objects on the ground
- Reflection: Bouncing of light rays off of a surface. Most of the light we see!!!
- Absorption: Transfer of light energy. Compounds absorb light of specific wavelengths
and reflect others
- Refraction: Bending of light rays when traveling from one transparent medium to
another. This bending occurs because of the speed of light difference between the two
,media. This is the property of most relevance to eye function.
- Cornea: The main refractive component (air in front, fluid (aqueous humor) behind)
Eye anatomy (pt. 1) - ANSWER - Pupil: Appears dark because of light-absorbing retinal
pigments; ENTRY FOR LIGHT!!
- Iris: Gives eyes it's color. Contains two muscles that control pupil size (one contracts,
one expands it)
- Cornea: Transparent; no blood vessels; cornea is the main refractive component and is
continuous with the sclera
- Sclera: Wall of eyeball; white of the eye; very tough; attached to 3 extraocular muscles
- Conjunctiva: Mucous membrane that covers the front of the eye and attaches eyelids to
the sclera
- Optic nerve: Carries axons from retina to brain; exists back of eye; reaches base of
brain near pituitary
Eye anatomy (pt. 2) - ANSWER - Retina: Neural tissue at the back of the eye: the main
sensory organ; PART OF THE CNS
- Optic desk: the area where blood vessels originate; an area where optic nerve exits the
retina; blind spot
- Macula: Middle of the retina; for central vision as opposed to peripheral; important for
fine vision (acuity) due to lack of blood vessels
- Fovea: Dark spot, a thinning of the retina; at the center of the macula, it is important for
high acuity vision; densely populated with cone photoreceptors which are important for
seeing color
- Lens: Concentrates, and focuses light at the retina (more close-up)
Eye anatomy (pt. 3) - ANSWER - The transparent lens is suspended by ligaments forming
a ring inside the eye
-Ciliary muscle controls shape of lens enabling eyes to adjust
their focus to different viewing distances
-Think of lens as a strawberry suspended in the center of a
bagel (ciliary muscle) by two toothpicks (zonule fibers); if the
muscle contracts it decreases the size of the hole and
squeezes the lens so it gets thicker
,Between cornea & lens: Aqueous humor (water-like)
Inside Eyeball: Vitreous humor (gel-like)
Eye disorders - ANSWER - Imbalance in extraocular muscles (DO NOT get this confused
with other muscles involved with the eye)
- Esotropia: cross-eyes (eso in esotropia * ss in cross)
- Exotropia: Wall-eyed (looking towards the exit by the wall)
- Glaucoma: Increased intraocular pressure due to poor fluid drainage or other causes,
which damages the optic nerve (pinches it) - build up of aqeous humor fluid
- Detached retina: can happen during aging, which causes shrinkage of vitreous (fluid
inside of the eye). As this happens, it can pull on your retina
- Macular degeneration: loss of central vision which occurs in 25% of people over age 65
*Dry: Due to protein deposits; 90% of cases
*Wet: due to abnormal blood vessels under the retina-swelling and bleeding; 10% of
cases
Notice the difference between the loss of central vision vs peripheral vision
- Retinitis pigmentosa: loss of peripheral and night vision due to degeneration of
photoreceptors; genetic
Image formation by the eye - ANSWER - The eye collects light rays emitted by or
reflected off objects and focuses them onto the retina to form images
- Cornea and lens bring objects into focus
- Cornea: site of most refractive power
- Lens: forms crisp images of objects closer than 9m from the eye
- As light passes into a medium where its speed is slowed, it will bend
- The light is bent as it moves from one medium (air) to another (liquid)
- The degree to which light bends is measured in diopters
- Cornea has a refractive power of about 42 diopters; the lens adds about a dozen more
Accomodation by the lens - ANSWER - Accommodation: Contraction of ciliary muscles
to change the shape (rounder, curved) of the lens
- Objects 9m or less from the eyes require this because rays of light emanating from any
point reach the eyes at stepper angles; requiring more refractive power
, - Ability to do this decreases with age
Vision correction - ANSWER - Hyperopia: Farsightedness (difficulty seeing close
objects) due to eyeball being too short, and point of focus is beyond the retina; correct
with convex lens (magnifier) to make image appear bigger and shortens the point of
focus so it hits the retin a
- Myopia: Nearsightedness due to eyeball being too long (light focuses before retina),
correct with concave lens that makes image appear smaller and lengthens the point of
focus so it hits the retina
Pupillary light reflex - ANSWER - The pupil contributes to optical functioning by
continuously adjusting for different ambient light levels
- Pupillary light reflex: Connections between retina & brain stem that control the
muscles in
the iris that constrict the pupils
-Consensual = shine a light in one eye and both pupils contract -Non-Consensual =
indication of a neurological disorder
- Constriction of pupil helps eye adjust to different levels of light, which has the
beneficial effect that it increases depth of focus/field (two points that are different
distances away from the eye can both be in focus)
Visual field - ANSWER - The structure of the eyes, and where they are positioned in the
head, limits how much of the world we can see at any one time.
-Visual field: Area seen by eye when looking forward
ACCURATE ANSWERS
Vision overview - ANSWER - Human vision is highly advanced relative to other animals
- One can think of the eye as having two functions:
* A camera-like system to focus light on the back of the eye (retina)
* The generation of a pattern of action potentials from the input of many photons
(quantum of light or other electromagnetic radiation) hitting photoreceptors (light
energy converted to electrical/ chemical energy)
- Our visual system detects differences in light intensity hitting different parts of the
retina
- Information gathered in the retina is sent to the primary visual cortex, but also to other
areas of the brain that influence biological rhythm, eye movement, control of the
pupillary light reflex, and shape of the lens
- All the complex data we need to construct our perception of the world is gathered by
the retina (kind of like a detector organ)
Properties of light (pt. 1) - ANSWER - Light: Electromagnetic radiation within the portion
of the electromagnetic spectrum that is perceived by the human eye (400-700 nm)
- Frequency: Waves per second (higher frequency = higher energy)
- Wavelength: Distance between peaks (determines frequency, and thus energy);
smaller wavelength = higher frequency
- Amplitude: Peak minus trough (how bright light is)
Properties of light (pt. 2) - ANSWER - Optics: The study of light and rays and their
interactions
- Light rays travel in straight lines until they interact with the atoms and molecules of the
atmosphere and objects on the ground
- Reflection: Bouncing of light rays off of a surface. Most of the light we see!!!
- Absorption: Transfer of light energy. Compounds absorb light of specific wavelengths
and reflect others
- Refraction: Bending of light rays when traveling from one transparent medium to
another. This bending occurs because of the speed of light difference between the two
,media. This is the property of most relevance to eye function.
- Cornea: The main refractive component (air in front, fluid (aqueous humor) behind)
Eye anatomy (pt. 1) - ANSWER - Pupil: Appears dark because of light-absorbing retinal
pigments; ENTRY FOR LIGHT!!
- Iris: Gives eyes it's color. Contains two muscles that control pupil size (one contracts,
one expands it)
- Cornea: Transparent; no blood vessels; cornea is the main refractive component and is
continuous with the sclera
- Sclera: Wall of eyeball; white of the eye; very tough; attached to 3 extraocular muscles
- Conjunctiva: Mucous membrane that covers the front of the eye and attaches eyelids to
the sclera
- Optic nerve: Carries axons from retina to brain; exists back of eye; reaches base of
brain near pituitary
Eye anatomy (pt. 2) - ANSWER - Retina: Neural tissue at the back of the eye: the main
sensory organ; PART OF THE CNS
- Optic desk: the area where blood vessels originate; an area where optic nerve exits the
retina; blind spot
- Macula: Middle of the retina; for central vision as opposed to peripheral; important for
fine vision (acuity) due to lack of blood vessels
- Fovea: Dark spot, a thinning of the retina; at the center of the macula, it is important for
high acuity vision; densely populated with cone photoreceptors which are important for
seeing color
- Lens: Concentrates, and focuses light at the retina (more close-up)
Eye anatomy (pt. 3) - ANSWER - The transparent lens is suspended by ligaments forming
a ring inside the eye
-Ciliary muscle controls shape of lens enabling eyes to adjust
their focus to different viewing distances
-Think of lens as a strawberry suspended in the center of a
bagel (ciliary muscle) by two toothpicks (zonule fibers); if the
muscle contracts it decreases the size of the hole and
squeezes the lens so it gets thicker
,Between cornea & lens: Aqueous humor (water-like)
Inside Eyeball: Vitreous humor (gel-like)
Eye disorders - ANSWER - Imbalance in extraocular muscles (DO NOT get this confused
with other muscles involved with the eye)
- Esotropia: cross-eyes (eso in esotropia * ss in cross)
- Exotropia: Wall-eyed (looking towards the exit by the wall)
- Glaucoma: Increased intraocular pressure due to poor fluid drainage or other causes,
which damages the optic nerve (pinches it) - build up of aqeous humor fluid
- Detached retina: can happen during aging, which causes shrinkage of vitreous (fluid
inside of the eye). As this happens, it can pull on your retina
- Macular degeneration: loss of central vision which occurs in 25% of people over age 65
*Dry: Due to protein deposits; 90% of cases
*Wet: due to abnormal blood vessels under the retina-swelling and bleeding; 10% of
cases
Notice the difference between the loss of central vision vs peripheral vision
- Retinitis pigmentosa: loss of peripheral and night vision due to degeneration of
photoreceptors; genetic
Image formation by the eye - ANSWER - The eye collects light rays emitted by or
reflected off objects and focuses them onto the retina to form images
- Cornea and lens bring objects into focus
- Cornea: site of most refractive power
- Lens: forms crisp images of objects closer than 9m from the eye
- As light passes into a medium where its speed is slowed, it will bend
- The light is bent as it moves from one medium (air) to another (liquid)
- The degree to which light bends is measured in diopters
- Cornea has a refractive power of about 42 diopters; the lens adds about a dozen more
Accomodation by the lens - ANSWER - Accommodation: Contraction of ciliary muscles
to change the shape (rounder, curved) of the lens
- Objects 9m or less from the eyes require this because rays of light emanating from any
point reach the eyes at stepper angles; requiring more refractive power
, - Ability to do this decreases with age
Vision correction - ANSWER - Hyperopia: Farsightedness (difficulty seeing close
objects) due to eyeball being too short, and point of focus is beyond the retina; correct
with convex lens (magnifier) to make image appear bigger and shortens the point of
focus so it hits the retin a
- Myopia: Nearsightedness due to eyeball being too long (light focuses before retina),
correct with concave lens that makes image appear smaller and lengthens the point of
focus so it hits the retina
Pupillary light reflex - ANSWER - The pupil contributes to optical functioning by
continuously adjusting for different ambient light levels
- Pupillary light reflex: Connections between retina & brain stem that control the
muscles in
the iris that constrict the pupils
-Consensual = shine a light in one eye and both pupils contract -Non-Consensual =
indication of a neurological disorder
- Constriction of pupil helps eye adjust to different levels of light, which has the
beneficial effect that it increases depth of focus/field (two points that are different
distances away from the eye can both be in focus)
Visual field - ANSWER - The structure of the eyes, and where they are positioned in the
head, limits how much of the world we can see at any one time.
-Visual field: Area seen by eye when looking forward
