A new study presented at the American Pain Society 33rd Annual Scientific Meeting found that a person’s eye color may help predict how their body responds to pain.
“There may be certain phenotypes that predict or indicate a person’s response to pain stimuli or drug treatment for pain,” said Dr. Inna Belfer, who presented the findings at the APS meeting. “Human pain is correlated with multiple factors like gender, age, and hair color. Researchers have found that red hair is associated with resistance to anesthetics and also to increased anxiety and darker eye color has been reportedly found to correlate with increased physiologic reactivity and drug-induced pupil dilation.”
To determine if eye color could be a predictor of pain tolerance, researchers documented eye color and pain-related traits in healthy women who were undergoing labor and delivery. Participants were asked to rate their pain, anxiety, depression and sleep both before and after delivery. The women were also divided into two groups based on their eye color, with 24 women in the dark eye group (brown or hazel) and 34 women in the light eye group (blue or green).
After analyzing the data, researchers concluded:
- Women with dark-colored eyes experienced more anxiety than women with light-colored eyes.
- Women with dark-colored eyes exhibited a higher likelihood of sleep disturbance and had less improvement in catastrophizing/rumination than women with light eyes.
- Individuals with light-colored eyes were more tolerant of heat pain and were less likely to be depressed as a result of their pain than darker-eyed women.
Although it appears women with lighter-colored eyes experienced less pain symptoms during labor, Dr. Belfer said the study had some limitations.
“Due to the small sample size, we can’t get compelling evidence for our findings, but we do feel that our study has revealed patterns that warrant further studies,” said Dr. Belfer. “We are going to see if there is a link between eye color and clinical pain in part 2 of this project, in men and in women, and in different pain models other than the labor pain model,” Dr. Belfer said.
Dr. Silverman comments
This is an interesting study and I’m intrigued to see the results of future studies on genetic makeup and pain, but there are simply too many variables to say conclusively that eye-color can be a good predictor of pain.
For example, some women may be more anxious simply because this is their first child, or they don’t yet know the sex of their baby. The study never asked if this was the woman’s first pregnancy, and as any woman with multiple children will tell you, the second time is often far less stressful since they know what to expect.
Also, as Dr. Belfer mentioned, only 58 women participated in the study. Until a larger population is studied, preferably in a more controlled environment, we won’t know how well eye color can predict a person’s pain tolerance.
Related source: Medscape.