the distance b/w successive peaks and troughs
the number of waves per second
the difference b/w wave trough and peak
electromagnetic radiation, photons, waves of energy
short wave lengths
Radiation emitted at high frequency have?
red or orange
An ex. of a color with a longer wavelength, hence less energy?
light energy being absorbed
photoreceptor cells in retina generate an action potential from?
Images are formed in the eye by?
blood vessels, aqueous humor
The cornea lacks what, and is nourished by what?
The cornea is continuous with ?
Extraocular mm. hide behind the what, which is a membraine that folds back from the inside of eyelids and attaches to the sclera?
Retinal vessels originate from where?
At the middle of retina, a darker region w/ a yellowish hue, area of central vision?
lack of large blood vessels
macula is distinguished by its absense of ?
Dark spot thats the pit, or center of the retina, and the thinnest part of the retina?
A transparent surface located behind the iris and it controls pupil size?
Zonule fiblers attached to ciliary mm.
Lens is suspended by?
Ciliary mm. are attached to the?
When the ciliary mm. contract the tension in the zonule fibers what, and the lens becomes what?
increases, stretch into a flat shape
When ciliary mm.relax, tension of the ligaments what, causing the lens to what?
watery fluid in b/w the cornea and the lens?
watery fluid in b/w the lens and the retina?
what gives the eyeball its shape?
Light rays hit the curved cornea and then bend so that they do what on the back of the retina?
bend, pass straight into the retina
Light that passes directly in the center of the cornea do not what, and instead do what?
the distance from the refractive surface to the point where parallel light rays converge is?
the shorter the focal distance
The tighter the curve of light, the?
Focal dist. measured in meters is?
slowing of light at the air-cornea interface
Refractive power depends on what?
B/c water passes light at close to the same speed as the eye, so the refractive power is eliminated
Why do things look blurry underwater with out a scuba mask on?
As objects get closer, light rays diverge and more refractory power is needed to bring them into focus, so ciliary mm. contract , decrease lig. tension, and the lens gets rounder which increases the refractory power.
An imbalance in extraocular mm of the 2 eyes, so the eyes point in diff. directions?
Direction of gaze diverges, wall eyed?
Clouding of the lens?
loss of visions due to intraocular pressure in aqeous humor which ipinges optic n.?
Condition where people may see shadows and flashes of light?
a progressive degeneration of photoreceptors, where theres a loss of night and peripheral vision and then blindness?
Loss of central vision due to yellowish deposits uner the macula?
When the eyeball is too short from front to back, then rays are focused behind the retina, creating farsightedness, b/c lens can't accomodate enough to image near points?
Farsightedness or hyperopia can be corrected by what type of lens?
If eyeball is too long (from front to Back), rays converge before reaching the retina, causing nearsightedness?
Nearsightedness or myopia needs what type of corrective lens?
Various irregularities in the curvature of the cornea or the lens that leads to reduction in refraction is ?
Old eye, or a hardening of the lens with age that denies the lens its elasticity so it can't round well enough for good accomodation, causing visual prob.?
bifocals: lenses are concave on top to assist with far vision, and convex on the bottom to assist with near vision
Describe the needed lens for presbyopia?
Light energy converted into neural signals?
Sight of static refraction
Sight of dynamic refraction
70% of refraction occurs at the ?
the more it bends the light
The more deeply curved the cornea is the more ?
less light is refracted
The flatter the cornea is the less?
30%, people who are more sensitive to the sun
Age related macular degeneration occurs in what % of people over age 75, and in what type of people more often?
loss of central vision, central scotoma, peripheral vision intact, sensitive to glares, and decrease contract sensitivity
Describe ARMD ?
microaneurisms, hemorrages, macular edema, abnormalities in retinal blood v., have functional loss of vission, dark spots
Describe Diabetic retinopathy?
Photoreceptors (rods/cones) connect to bipolar and horizontal cells which connet to ganglion cells which fire action potentials
Describe transduction of light energy into neural signals?
Which neurotransmitter is released in retina?
Multiple Sclerosis, glaucoma
Diseases of the optic Nerve: optic neuritis?
Regulation of sleep-wakefulness daily is a pathway from the optic nerve to the?
Control pupil size & certain types of eye movement, pupillary light response, turning head, posture movements in response to vision
Direct projections to the superior colliculus, pre-tectum of midbrain control?
10% for visual and sensorimotor syst. and for vision w/ postures and movements
What % of ganglion cells project to the superior colliculus (tectum of midbrain) for what?
elevation, depression, inward and outward rotation, adduction, abduction
What are the 6 cardinal ranges of gaze in the oculomotor ROM?
Inf. and Sup. obliques, Med. and Lat. obliques, Sup. and Inf. rectus mm
Name 6 extraocular mm?
Cranial N.3,4,and 11. Trochlear, Oculomotor, and Abducens
What are the extraocular mm innervated by?
Aiming & briefly holding the eyes on a target is what?
Following a smoothly moving target is what?
Changing fixation from point to point is what?
both eyes to make coordinated movements, steriopsis (depth perception), and vergence (convergence and divergence) so eyes move in opposite direction so image will be centered on both foveas
BINOCULAR VISION is needed for?
Coordinating movements to meet demands of time and space
SPATIOTEMPORAL ORIENTATION is what?
Neural mechanism responsible for our ability to maintain a foveated gaze and Compensatory eye movements in response to head movements
VESTIBULAR OCULAR REFLEX (VOR) is for what?
to the cerebellum, to cranial n. nuclei 4 and 3, and to spinal interneurons
Pathways from the superior colliculus go to where?
Non-striatal cortex sends info about visual manipulation of concepts and objects, the reticular formation sends info regarding orientation of vision, and the inf. colliculus sends info from vestibular and auditory syst., visual cortex send info on location of objects, basla ganglia info on preplanning of visual motor mov't, and from somatosensory syst.
describe where info to the superior colliculus comes from?
interpretation/analysis of visual information
Neural connections from Area 17 allow for what?
If secondary and tertiary zones of occipital lobe, area 18 and 19 are disrupted then?
how objects and movements are related in space, dysfunction=constructional apraxia
parietal lobe function and dysfuntion in visual perception?
integrate vision and mov't, dysfunction=ideamotor apraxia (can't perform purposeful mov'ts)
Connections to Motor and Premotor cotex have a role in vision how?
integrate vision and language; dysfunction= alexia, agraphia
Connections with language regions in temporal lobe have a role in vision how?