Find the approximate power in the 90th, 180th, 45th and 122nd meridians.
This power will not be recorded in the wearer's records or ordered from the lab.  It is a step in doing prism problems.  Therefore, it will not be rounded to 1/8 diopter steps;  it will be rounded to two decimal places.

Do this set using the formula and your calculator.
 

	90th	180th	45th	122nd
1.  +3.50 2.  -1.00 -1.00 x180 3.  +0.50 -2.00 x030 4.  -1.00 +1.00 x080 5.  -1.00 +3.00 x110 6.  +8.75 -2.25 x005 7.  -16.75 -2.00 x179 8.  -16.75 +2.00 x005  9.  -0.75 +1.00 x092 10.  -1.62 +1.75 x115 11.  +0.25 -0.50 x135 12.  pl -0.50 x058 13.  -4.25 14.  pl +3.75 x053 15.  +0.25 -0.50 x145 16.  +0.25 -0.25 x135 17.  +22.50 -3.50 x058  18.  -0.25 -0.50 x033 19.  +1.00 -2.00 x090	+3.50 -2.00 -1.00 -0.97 -0.65 +6.52 -18.75 -14.77 -0.75 -1.31 pl -0.14 -4.25 +1.36 -0.09 +0.13 +21.52  -0.60 +1.00	+3.50 -1.00 pl -0.03 +1.65 +8.73 -16.75 -16.73 +0.25 -0.18 pl -0.36 -4.25 +2.39 +0.09 +0.13 +19.98  -0.40 -1.00	+3.50 -1.50 +0.37 -0.67 +1.46 +7.82 -17.78  -15.92 -0.22 -0.07 -0.25 -0.03 -4.25 +0.07 -0.23 pl +22.32 -0.27 pl	+3.50 -1.72 -1.50 -0.55 -0.87 +6.96 -18.16 -15.16 -0.50 -1.59 +0.22 -0.40 -4.25 +3.27 +0.17 +0.24 +19.67 -0.75 +0.44

Find the approximate power in the 90th and 180th meridians.
This power will not be recorded in the wearer's records or ordered from the lab.  It is a step in doing prism problems.  Therefore, it will not be rounded to 1/8 diopter steps;  it will be rounded to two decimal places.

Do this set using the shortcut, without your calculator.
 
 

	90th	180th
1.  +2.50 -1.00 x030 2.  -3.25 +2.00 x135 3.  pl -2.00 x 150 4.  +3.00 -3.00 x045 5.  +3.00 -1.50 x060 6.  -5.00 7.  -1.25 -1.00 x180 8.  +2.00 -4.00 x120 9.  -1.00 +4.00 x060 10. +12.00 -2.00 x090	+1.75 -2.25 -1.50 +1.50 +2.63 -5.00 -2.25 +1.00 pl +12.00	+2.25 -2.25 -0.50 +1.50 +1.88 -5.00 -1.25 -1.00 +2.00 +10.00