Brain surgery has had some remarkable evolutions in the past. Today, the advent of new and more precision instruments such as the pupilometer allows for a better view of the brain's vessels' geometry and anatomy.

Pupillometry – the practice of measuring pupil size, has been around for centuries. Experts have used the pupilometer to evaluate pupillary response in traumatic brain injury. The technology used by medical professionals to measure pupils in this period depended upon various devices. Some used crystals, mirrors, and even cameras. Most of these instruments incorporated a scale for measurement, with some being elaborate and ornate, more so than practical. However, with advances in science and technology, scientists' development of simpler instruments made it possible to measure pupil size accurately and effectively.

Pupillometry deals with many more things

Furthermore, it has been shown that pupils dilate in direct proportion to the amount of cognitive work they are exposed to, with bigger pupils being associated with more cognitively demanding activities. A good illustration of this is the Stroop test, which requires participants to read the text in various colors (for example, the word "blue" is printed in a different color).

Increased pupil size is a sign that your brain is struggling to process emotions or bits of information. Because of functional magnetic resonance imaging (fMRI), pupil dilation is a helpful predictor for assessing mental activities at a deeper level. Scientists believe that improvements in brain activity in various regions are highly related to increased pupil size.

For example, aberrant pupillometry responses to stimuli have been seen in persons suffering from depression, anxiety, Autism Spectrum Disorder (ASD), and Parkinson's disease. A pupillary examination is a vital tool in understanding how healthy individuals work and what occurs within the mind of a sick person, to put it simply.

The fact that pupillary examination provides early insights into improving the short-term quality of life for those suffering from neurological disorders does not invalidate it. Psychiatric treatment success may be predicted to a certain extent based on pupillometry data, according to the findings of the study. The use of this method may help to guarantee that the patient gets the best available therapy, which may result in improved recovery rates and overall healthcare effectiveness.

It is possible that pupil dilation, as a secondary signal, might have a substantial influence when using BCI (brain-computer interface). People who have physical mobility constraints may find eye-tracking an accessible method of computer engagement, which is a common use for brain-computer interfaces. If the BCI process is correctly assessed, it may be possible to offer an extra cognitive signal, increasing the total effectiveness of the system.

The combination of other biosensors and pupillometry could even further advance brain-computer interfaces: "In particular, if personal computers could perceive a user's emotions through the use of physiological measures such as heart rate, galvanic skin response, EEG, pupil diameter, and so on, then it could intelligently alter a user's experience," Grau and Siegel write in their paper on the subject.

How do doctors perform pupillometry?

Anyone may begin exploring the wonderful world of pupillometry with simply a pupillometry device, a specified stimulus (or stimuli), and NeurOptics. Because it is a non-invasive therapy, it is simple to set up and keep running. With eye-trackers, there is typically no need for special pupillometry equipment since they can perform the required functions.

A pupillary evaluation must take into consideration the quantity of light that is shining on the subject matter. It is necessary to standardize the luminescence of the stimuli to verify that any pupil reflex is not purely a biological response to light intensity.

After this has been taken into account, the experiment may be launched (together with the degree of illumination in the room). Additionally, integrating data from additional biosensors may improve the quality of the study's conclusions.

Experts may utilize EEG signals to determine precise measurements of a person's pupil reactivity, recorded and analyzed. This information may be used to determine the amount of cognitive strain experienced by the person in question (among other metrics). When an EEG and pupillometry are used together, it is possible to determine whether increased pupil dilation is caused by cognitive load or other reasons.

Additionally, frontal asymmetry may be examined using EEG to determine if a participant is more likely to approach or avoid a stimulus in the context of their research. Due to the automated calculation of this parameter in iMotions, it is easy to determine the underlying reason for pupil dilation.

More physiological sensor combinations might be added to the evaluation of pupillary reaction to better understand a person's thoughts, emotions, and behaviors. Face reading may be used to determine a person's emotional valence. The other eye-tracking metrics, on the other hand, allow researchers to establish what the subject is looking at, how it impacts their mood or behavior, and how strong that mood or behavior is in comparison.

Conclusion

Pupillometry is a technique that may be used for various purposes, including advertising testing, user experience testing, psychological testing, and more. It assesses the strength of stimuli and pupil response in a variety of situations. It is critical to understand the limitations of a pupillometry experiment before proceeding with it. Because of the vast amount of information it contains, it is still an essential resource for psychologists and other behavioral scientists. It will be a long time before it is no longer relevant.