Related Experiment Video
Updated: May 11, 2026
Objective Nociceptive Assessment in Ventilated ICU Patients: A Feasibility Study Using Pupillometry and the Nociceptive Flexion Reflex
Published on: July 4, 2018
Pupillometry: the influence of gender and anxiety on the pain response
Adriana L Bertrand1, João Batista S Garcia, Erica B Viera
1Federal University of Maranhao, Sao Luis, Maranhao Brazil.
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 Maranhao, 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.
