Von Bartheld: Vision 1 Flashcards
A convex lens is a converging lens, and has a (blank) focal point
positive
A concave lens is a diverging lens, and has a (blank) focal point
negative
What is the focal point?
the distance of the focal point (image formation) from the lens
What is the equation for a diopter?
1/focal length
A 10 diopter lens has a focal length of (blank)
10 cm
What is the equation for focal power?
refractive index/focal length
What structure is primarily responsible for refractive power?
anterior curvature of the cornea
What’s this:
Accommodation decreases with age
presbyopia
Nearsightedness
myopia
Farsightedness
hyperopia
In myopia, what kind of lens do you use?
concave
In hyperopia, what kind of lens do you use?
convex
What’s this:
Vision is blurred due to irregular curvature of the cornea or lens. The cornea may not be perfectly round, but may have a “football shape.”
astigmatism
What creates the blind spot?
the optic nerve
What are the 5 cell types in the retina?
Which cells are closest to the light?
Which cells are close to the pigment epithelium?
ganglion cells *insert into optic nerve, closest to light bipolar cells amacrine cells horizontal cells rods/cones *close to pigment epithelium
Where are the rods primarily located?
Where are the cones primarily located?
most rods in the periphery, very few in the fovea
most cones in the fovea
Are there rods or cones in the area outside of the fovea?
there is a mix of both!
think of the rods decreasing as you get toward the fovea and the cones increasing abruptly as you get toward the fovea
The fovea is a (blank) zone with several (blank)
avascular; cones
Rods and cones have a close relationship with the (blank)
pigment epithelium
What part of the rod cell is shed and renewed every couple of weeks or so?
photoreceptor disc
Do rods or cones adapt more quickly to a light stimulus?
cones; rods are not as fast adapting
How do rods differ from cones in terms of their convergence onto bipolar cells?
1 cone: 1 bipolar cell
several rods: 1 bipolar cell
What happens to cone cells in response to light?
hyperpolarization
Rods have Na+, K+, and Ca+ channels. How do these channels differ in light vs. dark?
In the dark, the channels are open and Na+ and Ca++ can flow in, while K+ flows out. This leads to depolarization. In the light, the channels close, leading to hyperpolarization.
