Eye Flashcards
where is the eye found and why?
pair in front of the eye to create a field of vision (area that can be seen)
Binocular vs stereoscopic vision?
Binocular vision is two eyes creating separate overlapping images which is converted and interpreted as one image by the brain
stereoscopic vision is the ability of to create 3D images to judge distance, depth and size
Eye diagram and functions(13)
Sclera- inelastic white layer covering the eye toward the posterior
protect from internal eye structures
maintain eye shape
Choroid- dark layer of pigments and blood vessels
pigments absorb light to prevent reflection
blood vessels provide oxygen and nutrients to the receptors in retina
Retina- layer containing light sensitive receptors, rods and cones
rods for dim light (night vision and peripheral)
cones for bright light and to distinguish
Blind Spot- area with no rods or cones (no vision)
allow blood vessels to enter with nutrients and oxygen
allow optic nerve to leave with nervous impulse from sensory neurons from receptors
Yellow spot- indentation of most cones- area of clearest vision
Cornea- convex transparent anterior part of sclera
allow light to pass to retina
convex for refraction of light
lens- elastic, transparent, biconvex structure behind pupil attached to suspensory ligaments
allows light to pass to retina
alter shape for eye accomodation
iris- coloured portion of eye with opening (pupil) and two muscles which allow for light to enter eye through pupillary mechnism
melanin for protection from sun
ciliary body- think anterior extension of choroid with cilliary muscle to allow to contract and relax and alter suspensory ligament for accomodation
suspensory ligament- attached to cilliary body and lens which is tigthened and slackened for eye accomodation and hold lense in place
aqueos humour- behind cornea role in refraction and maintain shape of eye
viterous humour-behind lens role in refraction and maintain shape of eye
optic nerve- allow impulse to be transmitted from receptors through sensory neurons to cerbrum for interpretration
what protects eyes (2)?
connective tissue and fat from mechanical injury
eyelashes from foreign bodies entering eye
define accomodation
ability of lens of eye to alter it’s shape when viewing near or distant objects
Accomodation near vs Far (6 each) with diagram
near: ciliary muscles contract
suspensory ligaments slacken
lens becomes more convex
light is refracted more
image is focused on retina
Distant: ciliary muscles relax
suspensory ligaments tighten
lens becomes less convex
light is refracted less
image is focused on retina
define pupillary mechanism
process by which the pupil diameter is altered to control the amount of light entering the eye.
Bright light vs Dim light with diagrams (4 each)
Bright:
radial muscles relax
circular muscles contract
pupil diameter constricts
less light enters
dim:
radial muscles contract
circular muscles relax
pupil dialates
more light enters eye
what is short sightedness with diagram and 3 reason, how to cure
ability to see nearby objects but not clear distant objects
cornea too curved
eye too long
inabillity of lens to become less convex
defected eye refracts light too much and light focused short of retina
concave lense worn to refract light outward allowing for image to be focused on retina
what is long sightedness with diagram and 3 reason, how to cure
ability to see distant objects but not clear nearby objects
cornea not curved enough
eye too short
inabillity of lens to become more convex
defected eye refracts light too less and light focused after retina
convex lens worn to refract light inward allowing for image to be focused on retina
what is astigmatism (diagram)
3 symptoms
3 treatments
when the cornea or lens is not equally rounded from all directions result in uneven refraction and image unevenly focused on the retina
blurred vision
headaches
eye squinting
contacts
eye glasses
laser therapy
What is a cataract and treatments?
transparent lens becomes cloudy and light cannot pass through cleary as a result of clumps of protein forming- increases in size
glasses or surgery to insert synthetic lens
