Power crosses, Transposition And Spherical Equivalent

Question 1

-3.00 -1.00 x 090
Where is the sphere power

Answer 1

Left. -3.00

Question 2

-3.00 -1.00 x 090
Where is the cylinder power

Answer 2

Middle. -1.00

Question 3

-3.00 -1.00 x 090
Where is the cylinder axis

Answer 3

Right. 090

Question 4

Convex lenses

Answer 4

Plus power, image magnified, behind the lens, real and inverted

Question 5

Concave lenses

Answer 5

Minus power, image minified, in front of lenses, virtual and upright

Question 6

Determine the prescription
-2.50+3.00x090

Answer 6

1.Add the Cylinder power to the sphere power
2. Change sign of Cylinder
3. Change the axis of the cylinder by 90•
+0.50-3.00x180

Question 7

Spherical equivalent
+1.75-4.00x180

Answer 7

1. Add half of the cylinder power to the sphere power
2. Remove the cylinder power and axis
   -0.25 DS

Question 8

Determine the perception based on the power cross provided
-1.00
|___ +2.00

Answer 8

+2.00 -3.00 x180 or
-1.00 + 3.00 x90

Question 9

Draw the power cross based on the prescription
+1.25-1.00x180

Answer 9

+0.25
|____+1.25

Question 10

Draw the power cross based on the prescription
-1.75-2.00x90

Answer 10

-1.75
|___ -3.75

Question 11

Transpose prescription to minis cylinder
-2.50+1.25x030

Answer 11

-1.25-1.25x120

Question 12

Transpose the prescription to a plus cylinder
+3.50-1.50x045

Answer 12

+2.00+1.50x135