Unit 1

Question 1

Vergence

Answer 1

The simultaneous movement of the pupils of the eyes during focusing

Question 2

Optics

Answer 2

Light reaches the eye and we see

Question 3

Christian Huygens

Answer 3

Proposed wave theory of light: lights comes in waves and spreads out in all directions.

Question 4

Isaac Newton

Answer 4

-Corpuscular theory of light: light is emitted by tiny particles called corpuscles
-geometric nature of reflection could be explained if light were made from particles
-7 visible colours

Question 5

James Clerk Maxwell

Answer 5

-Father of modern physics
-electromagnetic theory of light
-light waves have electrical and magnetic properties

Question 6

Max Planck

Answer 6

Light waves travel as packages of energy called photons
-quantum theory

Question 7

Albert Einstein

Answer 7

-light waves travel at a constant speed
-theory of relativity

Question 8

Leon Foucault

Answer 8

Accurately determined speed of light

Question 9

Wavelength, frequency, speed

Answer 9

Frequency=speed/wavelength
F=v/λ
Frequency is inversely related to wavelength

Question 10

Electromagnetic spectrum wavelengths: shortest-longest

Answer 10

Gamma rays, x-rays, UV, visible spectrum, Infrared, Microwaves, radio waves

Question 11

Electromagnetic spectrum wavelengths: longest to shortest

Answer 11

Radio waves, microwaves, infrared, visible, UV, x-rays, gamma rays

Question 12

Foot candle

Answer 12

Light from a single candle falling on a surface 1 foot away (1lumen/sq. ft.)

Question 13

Lumen (luminous flux)

Answer 13

-Quantity of light emitted per second
-16 lumens per watt

Question 14

Lux

Answer 14

1 lux is produced when 1 lumen is incident on one square meter area. 1 Lux is always 1 lumen/sq. m.
-1 lux = 10.764 lumens

Question 15

Geometric optics

Answer 15

-Branch of optics dealing with light rays
-study of effect of mirrors and lenses on light rays

Question 16

Real image

Answer 16

Point source on left, image on left

Question 17

Virtual image

Answer 17

Point source on left, image on right

Question 18

Concave mirrors

Answer 18

-Real, inverted, minified
-converging mirror

Question 19

Convex mirror

Answer 19

-virtual, erect, minified
-diverging mirror

Question 20

Refraction of light

Answer 20

Light moves from less dense material to more dense material and the shape bends. (Like a straw in a glass of water)

Question 21

Index of refraction

Answer 21

N=speed of light in (medium 1)/ speed of light in (medium 2)
N=n1/n2

Question 22

Snell’s law

Answer 22

(n1)sin(θ1)=(n2)sin(θ2)

Where n=refractive index of medium

And θ=angle of incidence(1) and refraction(2)

(The numbers here are not numbers but distinctions and should be in subscript)

Question 23

Light bends toward ______ of prism

Answer 23

Base

Question 24

1 prism diopter will displace an image 1 __ at a distance of 1__
-express in equation form

Answer 24

-1cm at a distance of 1m
-P=C/D
Where P=prism power (PD)
C=displacement (in cm)
D=object distance from prism (in m)

Question 25

Convex and concave: positive or negative powers

Answer 25

Convex: + power Concave: - power

Question 26

Converging lens

Answer 26

-plus power -Focal point is behind convex lens

Question 27

Diverging lens

Answer 27

-minus power -Focal point is in front of concave lens

Question 28

Vergence power

Answer 28

-measured in diopters (D) -Reciprocal of the distance between a point of reference and the point of focus -P=1/f Where P=vergence power f=distance (in m) from point of focus

Question 29

Distance of the OBJECT from the lens

Answer 29

U= 1/u Where U= vergence of the object rays (D) u=distance from lens (m)

Question 30

Distance of the IMAGE from the lens

Answer 30

V=1/v Where V=vergence of the image (D) v=distance (m)

Question 31

Image AND object vergence equation

Answer 31

V=U+P

Question 32

Image and object vergence: location of positive and negative figures

Answer 32

Positive: image is behind lens Negative: image is in front of lens

Question 33

P=C/D

Answer 33

P=prism power (PD) C=displacement (cm) D=object distance from prism (m)

Question 34

P=1/f

Answer 34

P=vergence power (D) f=distance from point of focus (m)

Question 35

U=1/u

Answer 35

U=vergence of the OBJECT rays (D) u=distance (m)

Question 36

V=U+P

Answer 36

V=vergence of image U=vergence of object rays P=power of lens

Question 37

U= V= u= v=

Answer 37

U=vergence of OBJECT rays V=vergence of IMAGE RAYS u=distance of the OBJECT from the lens v=distance of the IMAGE from the lens

Question 38

Magnification

Answer 38

Image size/object size OR Image distance/object distance

Question 39

Plano

Answer 39

No sphere power

Question 40

Perscription transposition how to

Answer 40

Sph/cyl/ax A B C 1)A+B 2)change sign of B 3) rotate axis

Question 41

Spherical equivalent

Answer 41

-A way to convert astigmatism prescription into just sphere for contact lenses -if cylinder is less than 1

Question 42

How to determine spherical equivalent

Answer 42

-add half of the cylinder power to the sphere power -remove cylinder and axis

Question 43

Refractive interfaces within the eye

Answer 43

Anterior cornea, posterior cornea, anterior lens, posterior lens

Question 44

Refractive power of the eye -corneal power -lens power

Answer 44

-total refractive power: 60D -corneal power: 43D -lens power: +15D to +20D

Question 45

The reduced or simplified eye (Gullstrand’s schematic)

Answer 45

-assumes all power occurs at the corneal interface -is 58.60D -is 22.6mm in length -anterior focal point is 17mm in front of cornea -nodal point is 5.6mm behind cornea

Question 46

Optical pathway

Answer 46

-retina -optic nerve -optic chiasm -Lateral genticulate body (LGB) -optic radiations -visual cortex

Question 47

Emmetropia

Answer 47

The focal point for parallel rays coming into the eye is ON the retina (needs no correction)

Question 48

Ametropia

Answer 48

-refractive error is present -myopia (short but forms a point) (eyeball is longer) -hyperopia (long but forms a point)(eyeball is shorter) -astigmatism (doesn’t form a particular point)

Question 49

Conoid of Sturm

Answer 49

Spherocylincrical lens produces two perpendicular focal lines -circle of least confusion is the area closest to a sphere. Occurs midway between the lines. Best overall focus

Question 50

Aniseikonia

Answer 50

Unequal image size between eyes. If not corrected can cause lazy eyes. The better eye will get used and the worse eye will stop being used.

Question 51

Anisometropia

Answer 51

Unequal refractive powers between eyes.

Question 52

Antimetropia

Answer 52

Eyes are positive and negative

Question 53

Accommodation

Answer 53

Eye changes it’s power to focus on near objects. Ciliary muscle contracts to cause increased power of eye’s lens.

Question 54

Amplitude of accommodation

Answer 54

Measured in Diopters. Gradually decreases with age. Lens becomes less flexible.

Question 55

Donder’s table

Answer 55

Age: 10 20. 30. 40. 50. 60. 70. Acom: 14 10. 7 4.5 2.5 1 0.25

Question 56

Accommodative conditions

Answer 56

Presbyopia- loss of accommodation with aging Latent hyperopia- amount of hyperopia that can be overcome with accommodation.