Axes and angles

Question 1

any two optical system is required to be aligned _________ to do efficient transmission

Answer 1

aligned coaxially

Question 2

the pupil is decentered________ and the fovea is decentered_____________

Answer 2

Pupil: nasally
Fovea: temporally

Question 3

what is the optical axis of the eye?

Answer 3

• the axis containing the centers of curvature of the eye’s optical surfaces
• line of rotational symmetry

Question 4

can purkinji images reflected from four surfaces of decentered eye be aligned?

Answer 4

nope

Question 5

rotationally symmetric optical systems need one axis, which is what?

Answer 5

optical axis

Question 6

what is the visual axis?

Answer 6

• the line connecting the foveola and the fixation point passing through the nodal points
• no chromatic aberrations

Question 7

the place of intersection of visual axis with the cornea is called…

Answer 7

ophthalmometric pole

Question 8

is the visual axis dependent on pupil position?

Answer 8

-nope

Question 9

what is the pupillary axis?

Answer 9

the line normal to the cornea passing through the center of the pupil
-we do not care if it hits the fovea

Question 10

what axis is good to measure the amount of eccentris fixation?

Answer 10

the pupillary axis

Question 11

eccentric fixation is an adaptation to what?

Answer 11

heterotropia

Question 12

what is the line of sight?

Answer 12

ray from fixation point that reaches the foveolar via center of the pupil

Question 13

what is the point called where the line of sight intercepts the cornea?

Answer 13

corneal sighting center

Question 14

the line of sight is a useful reference when examining what?

Answer 14

corneas that are undergoing refractive surgery

Question 15

what is the achromatic axis?

Answer 15

• the line connecting the nodal point and the center of the pupil
• no chromatic aberrations
• DEPENDENT ON PUPIL POSITION

Question 16

what is the fixation axis?

Answer 16

the line passing through the fixation point and the center of rotation of the eye
-depends on direction of rotation

Question 17

what is the fixation axis a good reference for?

Answer 17

measuring eye movements

Question 18

what is the keratometric axis?

Answer 18

the line passing through the fixation point and the center of curvature of anterior cornea

Question 19

the keratometric axis is used for alignment in what?

Answer 19

corneal topography measurements

Question 20

the point at which the keratometric axis intercepts the cornea is called what>

Answer 20

vertex normal

Question 21

what is the photoreceptor axis?

Answer 21

-light arriving a the retinal plane along the photoreceptor axis will be totally internally reflected and have a higher probability of being absorbed by the photopigment

Question 22

what is the neural axis?

Answer 22

increasing eccentricity declines image quality because there are less cones

Question 23

what is angle alpha?

Answer 23

• angle between the optical and visual axis

- angle formed at first nodal point by the optical axis and visual axis

Question 24

if the angle between the visual axis and the optical axis is considered to be positive when?

Answer 24

when the visual axis is on the NASAL side of the optical axis in OBJECT space

Question 25

what is angle lambda?

Answer 25

angle between the pupillary axis and the line of sight

Question 26

what is considered positive angle lambda?

Answer 26

-the pupillary axis is TEMPORAL to the line of sight in OBJECT space

Question 27

angle lambda is important for diagnosing what?

Answer 27

• eccentric fixation

- heterotropia

Question 28

what is angle kappa?

Answer 28

angle between the pupillary axis and visual axis

Question 29

angle kappa is the same as what?

Answer 29

angle lambda

Question 30

what is angle psi?

Answer 30

the angle between the visual axis and the achromatic axis

-both go through nodal points

Question 31

what is positive angle psi?

Answer 31

-the visual axis is inclined NASALLY to the achromatic axis in OBJECT space

Question 32

what is angle gamma?

Answer 32

the angle between the optical axis and the fixation axis

Question 33

angle gamma is within 1% of angle alpha for object distances_______________

Answer 33

greater than 50cm