Vision Flashcards
In what layer of the eye are the photreceptors located?
retina
What are the three layers of the uvea?
chroid
ciliary body
iris
What layer is continuous with the cornea?
sclera
Where to the extraoccular muscles insert?
sclera
These two muscles open the eye
levator palpibae
superior tarsal
This muscle closes the eye
orbicularis occuli
What is so special about the superior tarsal?
sm. muscle
NE –> alpha-1 receptors
sympathetic innervation
Which neurotransmitter do the orbicularis occuli and levator palpebrae muscles use?
ACh –> nAChR
Which neurotransmitter mediates the pattern generator for coordination of blinking?
dopamine
What is the corneal reflex?
closing of eyes to nociceptive pain
What is the optic reflex?
closing of eyes to bright light or rapidly approaching object
What are the 3 components of tears?
aqueous from lacrimal
lipid from lids
mucous from conjunctiva
What type of epithelium is found on the lens?
cuboidal
Refraction in cornea and lens: how are they different?
cornea: static, more powerful
lens: dynamic, less powerful
Emmetropic
eye that is refracting light normally
Optic axis
through geometric center, sharpest focus
Visual axis/fovea centralis
best color vision
Convergence
coordinated movement of eyes inward
Edinger-Westphal nucleus
cell bodies of preganglionic parasympathetic to ciliary muscle
Ciliary ganglion
cell bodies of postganglionic parasympathetic to ciliary muscle
Hyperopia
far-sighted
Myopia
near-sighted
Hyperopia: convex or concave
convex
Myopia: convex or concave
concave
What is a cataract?
decreased lens opacity
Pupillary sphincter
surrounds lens
Pupillary dialator
radiates from pupillary spincter
Where does sympathetic innervation to pupillary dialator come from?
superior cervical ganglion (NE)
Where does parasympathetic innervation to pupillary sphincter come from?
ciliar ganglion (ACh)
What produces aqueous humor?
ciliary body
Where is aqueous humor produced?
posterior chamber
What is the way out for aqueous humor
canal of Schlemm
How does the sympathetic nervous system affect intraocular pressure?
epinephrine stimulates beta-2 receptors, increases [cAMP] and increases inflow
norepinephrine stimulates alpha-2 receptors, decreases [cAMP] and decreases flow
How does bicarbonate generation affect intraocular pressure?
increased Cl- secretion, osmosis, and intraoccular pressure
What is primary outflow are for aqueous humor?
canal of Schlemm
What is uveoscleral outflow?
reabsorption of aqueous humor through ciliary muscle
What is the pathophys of glaucoma?
increased intraoccular pressure
What are the two types of glaucoma and the differences between them?
open angle: not dangerous
closed angle: medical emergency
Fovea centralis
90% of cones in retina
Three cone colors
blue, green, red
4 steps in visual transduction
- pigment activation
- G-protein activation
- phosphodiesterase activation
- closing is cGMP dependent
Spacial acuity
distinguish 2 points: eye chart
Temporal acuity
normally 50 Hz
Spectral acuity
2 colors as different
