Astigmatism And Correction Of Astigmatism

Question 1

Astigmatic systems do not form

Answer 1

Points, they form lines

Question 2

How many people have some form of astigmatism

Answer 2

80%

Question 3

One line is on the retina, one is in front of the eye. the vertical part of E would look clear

Answer 3

Simple myopic astigmat

Question 4

One line focused on retina, one focused behind retina

Answer 4

Simply hyperopic astigmat

Question 5

Both lines are in front of the retina

Answer 5

Compound myopic astigmat

Question 6

What state are you in when you are fogging the patient in refraction

Answer 6

Compound myopic astigmat

Question 7

Both lines behind retina

Answer 7

Compound hyperopic astigmat

Question 8

One line in front, one behind retina. CTC not on retina

Answer 8

Mixed astigmat

Question 9

One line in front retina, one behind the retina. CLC on retina

Answer 9

Equal mixed astigmat

Question 10

What does plus cylinder do?

Answer 10

Moves on line forward, moving CLC in front of retina

Question 11

What does minus cylinder do

Answer 11

Moves one line behind retina

Question 12

What does cylinder do

Answer 12

Moves just one line

Question 13

In what direction does minus cyl move the lone

Answer 13

Behind retina

Question 14

What direction does the plus cyl move a lone

Answer 14

In front of the retina

Question 15

What moves both lines in astigmatism?

Answer 15

Sphere

Question 16

A common vision condition that causes blurred vision. It occurs when the cornea is irregularly shaped or sometimes because of the curvature of the lens inside the eye

Answer 16

Astigmatism according to the AOA

Question 17

Methods for correcting astigmatism

Answer 17

• glassses (spherocylindrical lenses)
• contact lenses (toric)
• squinting (narrows aperture, lids can push on cornea)
• refractive surgery

Question 18

How many dimensions to a cylinder

Answer 18

3

Question 19

How do you generate a cylinder

Answer 19

Taking 2 parallel lines and roatating one around the other

Question 20

What is the center of rotation for a cylinder

Answer 20

Axis

Question 21

All points on the cylinder are ________ from the axis

Answer 21

Equidistant

Question 22

How can you create a cylinder

Answer 22

By taking a flat plane and rolling it so that the ends are circles

Question 23

Make sure you study the different shapes of optical lenses

Answer 23

Study it

Question 24

Power of a cylindrical lens

Answer 24

P1=(n2-n1)/r1

Question 25

If you shine a light through the ends of the cylinder what happens

Answer 25

Parallel light coming in, creates parallel light coming out

Question 26

What happens if you shine light on the side of the cylinder

Answer 26

Focuses into vertical line if standing up on end

Question 27

What direction does the light go through a cylinder

Answer 27

Same direction as cylinder is positioned, becomes line as it goes up and down cylinder

Question 28

A point object is located 25cm in front of a thin +10.00 D cylindrical lens with a vertical axis. The lens as a 50mm round aperture in front of it. What is the location of the image? Is it real or virtual?

Answer 28

+6D=1/6cm in back

Real because converging to a point

Question 29

Cylinders cannot exceed ______ degrees or be less than _____

Answer 29

180

0

Question 30

Angle increases from patients _____ to ______

Answer 30

Left to right

Question 31

Study cylinder crosses

Answer 31

Study it