Exam 2 - Vision Flashcards
What structure controls the shape of the lens and makes aqueous humor?
ciliary body
What structure controls the pupil opening?
iris
Where are photoreceptors found?
retina
Where is the area that is the most acute vision where only cones are present?
macula
What structure bends the light rays?
lens
Where is the focus point in the eye?
retina
What muscle contracts in miosis and what ANS controls it?]
circular muscle in the iris contracts causing pupillary constriction
parasympathetic - muscarinic receptors
What muscle contracts in myadriasis and what ANS controls it?
radial muscle in the iris contracts causing pupillary dilation
sympathetic - alpha adrenergic receptors
What structure is responsible for accommodation?
the ciliary muscle contracts or relaxes and affects the suspensory ligaments on the lens - flat lens for far vision, round lens for near vision
the radial or circular muscle of the iris contracts causing pupil contricted or dilated pupils - radial contraction for far vision, circular muscle for near vision
Describe Myopia and how you treat
nearsightedness; can’t see far away
image is focused in front of retina
bioconcave lens (diverging light rays)
Describe Hyperopia and how you treat
farsightedness; can’t see near
image is focused behind retina
bioconvex lens (converging light rays)
Describe astigmatism and how you treat
far and near are distorted
cornea is severely curved and only some light rays are focused
cylindrical lens
What fluid fills the anterior and posterior chamber (anterior compartment)?
aqueous humor
What fluid fills the posterior compartment?
vitreous fluid - gel like fluid
holds retina against choroids
Describe chronic (open-angle) glaucoma
Most common type
degeneration/obstruction of trabecular meshwork and canal of Schlemm decreases absorption of aqueous humor
-> intraocular pressure increases
-> pushes lens against retina causing damage of photoreceptors