Optics - VERGENCE

Question 1

Natural light has what type of VERGENCE?

Answer 1

MINUS vergence

Question 2

How do you calculate Refracting power of spherical surface?

Answer 2

Ds=(n’-n)/r ; r=in meters

Shade side with higher refractive index; if convex = PLUS power; if convex = MINUS power

Question 3

How do you calculate the Power of thin lens immersed in fluid?

Answer 3

Its the difference in the refractive index between the lens and the medium. (radius of curvature doesn’t change)
D air/D fluid = n lens - n air/ n lens - n fluid

Question 4

Gullstrand’s eye is an example of what type of lens? What happens to the nodal points in this model and why?

Answer 4

Thick lens, 2 nodal and 2 focal points. Different refractive medium on opposite sides of the lens causes both nodal points to be “pulled” into the medium with the higher refractive index.

Question 5

Reduced schematic eye has what power?
What are the two focal point distances?
What is the distance btwn the cornea and lens?
What is the total axial length?

Answer 5

1. 60 D
2. 17mm
3. 5.5mm
4. 22.5mm

Question 6

Dislocating and IOL posteriorly makes a patient more myopic or hyperopic?

Answer 6

Hyperopic