PTSD: Your eyes can reveal whether you've had traumatic experiences

  • Subjects of a study had an exaggerated pupil response when viewing happy or dangerous images
  • The study was done by Welsh academics
  • According to the team, the results could be useful in diagnosis and treatment of PTSD

Post-traumatic stress disorder (PTSD) is a disorder that can occur in people who have experienced or witnessed a shocking or scary traumatic event, such as a serious accident, a hijacking, or abuse.

According to new research by Welsh academics, a patient's pupils may reveal whether they’ve suffered a traumatic experience. The study was published in the journal Biological Psychology.

Led by Dr Aimee McKinnon at Cardiff University, the research team looked for traces of these traumatic events in the eyes of participants of the study who were suffering from PTSD. They did this by measuring the pupil of the eye while participants were shown threatening images (such as vicious animals or weapons), and images that showed neutral events, or pleasant images.

What the response showed researchers

Participants of the research included people with PTSD, as well as people who had been previously traumatised but were not living with PTSD.

After completing the tests, the researchers discovered that the response of participants with PTSD was different to participants who were not living with the condition, in that the pupils of those with PTSD grew larger as a result of the emotional stimuli than in the other participants.

The pupils of participants with PTSD were also found to show an exaggerated response to threatening stimuli. An unexpected result, however, was that the same result was found when they were shown "happy" or positive images, such as exciting sports scenes.

For Swansea University's Professor Nicola Gray, who co-authored the paper along with Professor Robert Snowden of Cardiff University, this is an important finding.

"This shows that the hyper-response of the pupil is in response to any arousing stimulus, and not just threatening ones. This may allow us to use these positive pictures in therapy, rather than relying upon negative images, that can be quite upsetting to the patient, and therefore make therapy more acceptable and bearable,” she said, further explaining that the idea now needs to be tested empirically before it can be rolled out into clinical practice.

Clinicians must understand impact of positive stimuli

McKinnon, who is now at Oxford University, also explained that their findings allow healthcare professionals to understand that people with PTSD are automatically primed for threat and fear responses in any uncertain emotional context, and to also consider what a burden this must be to them in everyday life.

"It also suggests that it is important for us to recognise that, in therapy, it is not just the fear-based stimuli that need re-appraising. If someone with PTSD is faced with any high-level of emotional stimulation, even if this is positive emotion, it can immediately trigger the threat system.”

Clinicians, therefore, need to understand this impact of positive stimuli in order to support their patients who are receiving mental health services, to overcome the challenges they face, said McKinnon.


People with PTSD run a high risk of developing psychiatric comorbidity, such as substance use disorder, major depression, and anxiety. Research published in 2017 in the South African Journal of Psychiatry indicated that PTSD and its associated after-effects are a huge public health concern in South Africa, especially for youth who experience high levels of trauma stemming from discrimination, abuse, interpersonal violence and traumatic events.

Symptoms of PTSD usually fall into four categories, explains the American Psychiatric Association (ASA)

  • Intrusive thoughts, such as flashbacks of the traumatic event
  • Avoiding reminders of the traumatic event, including places, people, and objects that serve as reminders of the event
  • Negative thoughts and feelings, such as ongoing fear, anger, guilt or shame
  • Arousal and reactive symptoms, which may include being irritable and having angry outbursts   

The South African Depression and Anxiety Group (SADAG) notes that a diagnosis of PTSD is made when the symptoms start to cause distress and interference in a sufferer’s daily life. The organisation also explains that symptoms typically appear within a few weeks of the trauma event, but there are rare occasions where there is a long period between the trigger event and the onset of PTSD symptoms, which can range from months to years. 

PTSD recovery

According to SADAG, psychiatrists and other medical professionals have success in treating the effects of PTSD, and include various treatment methods (such as cognitive behavioural therapy). Recovery time, they note, can range from six months upwards.

If you suspect you may be suffering from PTSD, reach out to a therapist as soon as possible, particularly one that specialises in the treatment of trauma and PTSD.

If you’ve experienced trauma and want to chat to a counsellor, contact SADAG’s toll-free line dedicated to trauma and PTSD on 0800 20 50 26. The line is open 8 am to 8 pm, seven days a week.

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