Unit 1: RGP Review

Question 1

With the rule, and against the rule, astigmatism are said to be defined if the meridian is within this many degrees

Answer 1

30

Question 2

What are the causes of irregular astigmatism?

Answer 2

-Trauma
-Keratoconus
-Degeneration
-Scarring

Question 3

What is the average curvature of a cornea?

Answer 3

43.00 D

Question 4

When calculating, corneal astigmatism, what meridian is the axis with the astigmatism?

Answer 4

The meridian with the SMALLER number (the flatter meridian)

Question 5

0.10 mm of base curve radius is equivalent to how many diopters?

Answer 5

0.50

Question 6

What is the equation for vertexing a contact lens

Answer 6

De=Dl/1-dDl

De= The power perceived by wearer
Dl= Actual lens power
d= Distance between where you want the lens and where it is. In meters.

Question 7

How much astigmatism can be corrected with a spherical GP lens?

Answer 7

2.50D

Question 8

What is residual astigmatism?

Answer 8

The amount of astigmatic refractive error that remains uncorrected with a contact lens.