Optics: Purkinji Images

Question 1

Image formed by reflection off the optical surfaces of the eye are referred to as __________

Answer 1

Purkinji image

Question 2

Four main refracting surfaces of the eye:

Answer 2

-anterior corneal surface
-posterior corneal surface
-anterior lens surface
-posterior lens surface

Question 3

Since there are 4 reflecting surfaces, there are four purkinji images numbered:

Answer 3

I, II, III, IV

Question 4

Purkinji image formation order:

Answer 4

-II
-I
-IV
-III

Question 5

Which purkinji image is the closest?

Answer 5

II

Question 6

Which purkinji image is the farthest?

Answer 6

III

Question 7

Purkinji reflection of I,II, and III form a _______ and ________ image

Answer 7

Virtual and erect

Question 8

Purkinji reflection of IV forms a ________ and __________ image

Answer 8

Real and inverted

Question 9

Purkinji reflection of the ________________ produces the strongest reflection

Answer 9

Anterior cornea (I)

Question 10

Image formed by the ____________ has the most magnification (2X)

Answer 10

Anterior lens (III)

Question 11

The first three images are formed by __________ reflecting surfaces

Answer 11

Convex

Question 12

The fourth purkinji image is formed by a ____________ reflecting surface

Answer 12

Concave

Question 13

The size and location of purkinji image III changes during _____________

Answer 13

Accommodation
(Decreases in size and moves closer to the surface)

Question 14

anterior lens surface radius of curvature decreases during __________________

Answer 14

Accommodation

Question 15

Purkinji images are important in several eye care applications:

Answer 15

-keratometry
-corneal topographers
-hirschberg test
-alignment of optical instruments with the eye (autorefractors, aberrometers and pupillometers)
-measurement of lenticular surfaces when measuring accommodation
-alignment and orientation during refractive surgery

Question 16

Keratometry is the measurement of curvature of cornea based on the ____ purkinji image

Answer 16

1st

Question 17

Keratometric is useful for….

Answer 17

Fitting contact lenses

Question 18

Corneal topographers

Answer 18

Clinical instruments used to determine the shape of the cornea and utilize purkinji image 1

Question 19

In the Hirschberg test the clinician views purkinji image ____when measuring angle _______

Answer 19

1, kappa

Question 20

Hirschberg test is used to determine…

Answer 20

The amount of eccentric fixation and measure the angle of strabismus

Question 21

In hirschberg test, if both eyes are aligned with the fixation light then…

Answer 21

Purkinji image I is located in the same position in each eye

Question 22

In a left eye exotropia when performing Hirschberg, the left eyes purkinji image is…

Answer 22

Located closes to the nasal edge of the pupil

Question 23

Each parameter of the purkinji image depends on…

Answer 23

IOL power, material, steps, and chromophores

Question 24

If the light is coming from infinity, to find f, you can…

Answer 24

Divide r by 2

Question 25

Corneal topographers are useful for:

Answer 25

-fitting CLs
-pre and post refractive surgery
-diagnosing certain conditions like keratoconus