Pupillometry: the influence of gender and anxiety on the pain response

Background: studies suggest that the pain response may be evaluated using pupillometry and is influenced by factors such as gender and anxiety. objectives: the aim of this study was to use pupillometry to observe the effects of gender and anxiety on the pain response. study design: a randomized,prospective,clinical and interventional study. setting: center for research on pain at the federal university of maranhão,brazil. methods: ninety-six patients were divided into groups according to their level of anxiety as indicated by the beck questionnaire. under photopic conditions and using retinography,these patients underwent pupillometry while a painful pressure stimulus of 1,500 kpa was applied to the middle phalanx of each patient's right middle finger using a pressure algometer. results: the pupil diameter increased in response to pain in all study participants,regardless of gender and anxiety level; the average pupil diameter was 3.265 ± 0.028 mm before the painful stimulus and 4.31 ± 0.200 mm for the duration of the stimulus (p = 0.0251). there was no significant difference between the genders in the level of anxiety (p = 0.614). regardless of gender,individuals with moderate to severe anxiety had higher average pupil diameters than individuals exhibiting mild or no anxiety (p = 0.019). men had a higher average pupil diameter than women (4.53 ± 0.345 mm and 4.48 ± 0.358 mm,respectively); however,this difference was not statistically significant in the presence of moderate to severe anxiety (p = 0.072). limitations: the number of men with high anxiety was insufficient to create their own group. conclusions: the pupil dilation in response to a painful stimulus was similar in both genders. additionally,regardless of gender,the average pupil diameter was greater in the presence of moderate to severe anxiety.