Lecture 1 - Optical Characteristics

Question 1

How much will a typical patients tolerate a slight error?

Answer 1

+ or - 0.50 D of refractive error

Question 2

How are Abbe Value and Chromatic Aberation related to one another?

Answer 2

Inversely Proportional

Question 3

If you a lens has a low index value, what will happen to the Abbe value?

Answer 3

Abbe Value will increase

Question 4

What is the heaviest lens material?

Answer 4

Glass

Question 5

What is the lightest lens material?

Answer 5

Trivex

Question 6

What is the imaginary line connecting the centers of curvature?

Answer 6

Optical Axis

Question 7

T or F. Light passing through the OC is refracted?

Answer 7

False

Question 8

Your mother-in-law’s lens PD and DBOC don’t match, what have you done to her glasses?

Answer 8

You have induced prism.

Question 9

For prism, which way will white light refract?

Answer 9

Base

Question 10

What type of light is refracted the most and which one is refracted the least?

Answer 10

Most - Violet

Least - Red

Question 11

What is the primary concern for lens designers?

Answer 11

Marginal Astigmatism

Question 12

For curvature of field, if marginal astigmatism is fully corrected, what can occur?

Answer 12

Peripherally viewing will decrease

Question 13

What are the two types of distortion?

Answer 13

Minus - Barrel
Plus - Pincushion
Note: This occurs with lens magnifications through lens PERIPHERY

Question 14

For people who drive at night, as a doctor what would be your primary concern for your patient?

Answer 14

Spherical Abberration

Question 15

Light rays that are oblique to the optic axis and cause a comet like tale, what kind of effect or problem is this?

Answer 15

COMA. When you’re looking form the top, the bottom will look larger.

Note: Can be corrected via surgery

Question 16

As your prescription changes from +2.00 to plano, what has happened to the shape of the lens?

Answer 16

It has flattened

Question 17

Why is it specific to have a base curve and why not give a base curve for everything?

Answer 17

The clinical abberation would be too high

Question 18

While looking at a horizontal line, you move a minus sphere lens down, what type of motion will it be Against or With?

Answer 18

With. Minus Sphere

Hint: Think of a concave lens and the line traveling towards the apex.

Question 19

Using an astigmatic lens, you rotate the lens counterclockwise and you notice the line you look through it is going clockwise, what type of break is this?

Answer 19

Against. Plus lens

Question 20

When looking at sphero-cylinder lense, what can break tell you and what can the motion tell you?

Answer 20

Break - Meridians
Motion - Power

Note: W will be the most plus or least minus of the two meridians

Question 21

If an unknown lens shows “against” motion with no trial lens in place. You use a -3.00 trials lens in combination with the unknown lens shows “with” motion. What is the power of the unknown lens?

Answer 21

The power would be less than +3.00

Question 22

Your patient has rotated his right lens 17 degrees clockwise in order to see better. Their original lens axis is 170 degrees. What is the new axis that you will prescribe?

Answer 22

7 degrees