Table 4 Mean differences between contrast sensitivity conditions for all spatial frequencies.

From: Effects of cannabis on visual function and self-perceived visual quality

Spatial frequencies (cpd)

Group 1 (N = 10)

(mean (SD))

Group 2 (N = 21)

(mean (SD))

z

p value

0.75

3.80 (12.02)

23.00 (33.62)

− 1.666

0.19

1.5

0.00 (0.00)

7.14 (17.93)

− 1.237

0.55

3

− 5.00 (15.81)

2.14 (36.90)

− 0.307

0.85

6

15.00 (47.43)

21.90 (65.64)

− 0.203

0.85

12

20.80 (34.93)

39.76 (52.28)

− 1.240

0.23

18

− 9.20 (15.54)

8.48 (19.14)

− 2.390

0.017

  1. A positive value corresponds to worsened contrast sensitivity after smoking cannabis.
  2. Mann–Whitney U test was applied for comparisons.