Anat and physiology of vision 1 Flashcards
4 function of eye
- transmit light to retina
- refract light so it is focussed on retina ( cornea and lens)
- transduce light into an electrical signal (rod and cones)
- process this signal before it goes to CNS (middle retinal layer)
2 segments of eye and what is in them
- anterior - anterior and posterior chambers
2. posterior - vitreous, retina, choroid and nerve
6 contents of anterior segment
- sclera
- cornea
- ant. chamber
- iris
- ciliary body
- lens
what is sclera
white outer coat of eye - perforation posterior for optic nerve and site of muscular attachment
what is conjunctiva
clear modified mucous membrane covering the sclera
3 functions of conjuntiva
- protects globe
- produces part of tear film
- vascular
3 portions of conjuntiva
- palpebral
- forniceal
- bulbar
what is episclera
vasular plexus between conjunctiva and sclera
2 layers of episclera
superficial and deep vessels
what is refractive power and focus of lens and cornea
cornea - 2/3 and fixed
lens - 1/3 and variable
3 reasons cornea is transparent
- avascular
- uniform structure
- deturgescence - dehydrated
what is nerve supply to cornea
V1
5 layers of cornea
- epithelium - non kerat. strat squamous - regenerates
- bowmans - dense collagenous
- stroma - 90% - regular collagen - doesn’t regen
- descemets - basement membrane
- endothelium - monolayer for hydration
what is diff between sclera and cornea
sclera is same basic components, but is irreg. collagen and is not opaque
2 ways cornea can lose transparency
- trauma - produces a scar
2. loss of endothelial function - swelling
4 parts of lens
- capsule
- epithelium
- nucleau
- cortex
what is a cataract
any opacity in the lens
3 types of cataracts and their causes
- cortical
- nuclear sclerosis - aging
- posterior subcapsular - steroid, diabetes
2 types of lenses that can be put in surgically
- posterior chamber
2. anterior chamber
3 parts of the uvea
- iris
- ciliary body
- choroid
what is div. of anterior and posterior segments
iris
function of iris
controls amount of light coming into eye
what is in the stroma
- muscles
- melanocytes
- pigments
2 types of muscles and their ennervations
- sphyincter - parasym via CN3
2. dilator - symp
what determines eye color
how much pigment is imbedded in stroma
what is ciliary body
middle part of uvea - ringlike structure located behond iris
2 parts of ciliary body
- pars plicata
2. pars plana
2 funcitons of ciliary body
- produce aqueous humor
2. accomodation
what aqueous humor
provide metabolic support to the lens and inner chamber
flow of aqueous humor
post. chamber>through pupil>ant. chamber> drained by trabecular network in angle
what causes glaucoma
obsturction of drainage of humour
what attaches lens to ciliary body
zonules
what is the near triad
- accomodation - ciliary body constricts and relaxes the zonules
- convergence of eyes
- pupil constriction - to decrease spherical abberation
what is vitreous humor made of
99% water, 1% collgen - gel
where does vitreous attach
optic nerve, retinal blood vessels, macula
4 parts of retina
- optic disc
- macula
- vessels
- peripheral retina
how many layers in retina
10 - light passes trough 8 to hit rods and cones
what is at base of retina and importance
retinal pigmented epithelium - BRbarrier and support
what is choroid
layer around retina that provides much of the metabolic requirements to retina
what are 4 extraocular parts of the eye
- bony orbits
- eyelids
- lacrima system
- extraocular muscles
what is weakest part of the orbit
the floor
3 opening into the orbit and what passes through them
- optic foramen - optic nerve and opthalmic artery
- sup orbital fissure - CN 3,4,V1,6
- inf orbital fissure - sympathetics and vessels
which is only muscle not attached to tendinous ring
inf. oblique
what closes lid
obicularis oculi - CN 7
2 innervations of the lid
- CN3 to open
2. sympathetics via mullers muscle
3 layers of tear film, where produced and function
- mucin - by conjuntiva - adhernce
- aqueous - lacrima glands - bulk of film
- lipid - meibomian gland in lid - reduces evap
drainage path of tear
punctum>canaliculi>lacrimal sac>nasolacrimal duct
