Table 1 Results of the discrete Fourier transform of 256 discrete PDφ values for the glass prism and the corneal prism.

From: The virtual prism represents the decentration component of the first-order term in a Fourier series of the corneal refractive power

|PD0| ()

α0 (radians)

Amplitude () at frequency (c/c)

Phase (radians) at frequency (c/c)

1 c/c

2 c/c

3 c/c

4 c/c

5 c/c

1 c/c

2 c/c

3 c/c

4 c/c

5 c/c

Glass prism (n1 = 1.525)

 1

0.019

1.000

0

0.000

0

0.000

π

na

π

na

π

 5

0.095

5.049

0

0.003

0

0.000

π

na

π

na

π

 10

0.190

10.393

0

0.024

0

0.000

π

na

π

na

π

 15

0.284

16.344

0

0.087

0

0.001

π

na

π

na

π

 20

0.376

23.255

0

0.222

0

0.003

π

na

π

na

π

Corneal prism (n1 = 1.376)

 1

0.036

1.002

0

0.000

0

0.000

π

na

π

na

π

 5

0.178

5.215

0

0.008

0

0.000

π

na

π

na

π

 10

0.354

11.776

0

0.069

0

0.000

π

na

π

na

π

 15

0.529

21.318

0

0.240

0

0.003

π

na

π

na

π

 20

0.701

36.245

0

0.607

0

0.014

π

na

π

na

π

  1. |PD0|, nominal value of prismatic power; , prism diopters; α0, apex angle of prism; c/c, cycles/circle; na, not applicable.