pupillary evaluation

Harnessing The Power Of New-Age Technology To Evaluate Pupil Size


In terms of eye anatomy, the pupil is situated within the iris and controls the amount of light that can be focused on the retina before it reaches the lens. The iris muscles carefully regulate the size of this opening. These instantly restrict the pupil from exposure to bright light and dilate the eye pupil in the presence of dim light. The parasympathetic neural fibers from the oculomotor nerve innervate into the muscles that constrict the pupil. The sympathetic nerve fibers help the pupil to control dilation.

The pupillary opening is narrowed when it is focused on closer and dilated objects for a farther vision. Upon its maximum contraction, the adult pupil measures less than 0.04 inches or 1 mm in diameter. It has teh capability to increase 10 times to this diameter.

The human pupil’s size varies according to age, trauma, stress, disease, and other abnormal conditions of the ophthalmic system that includes dysfunction of the eye. Hence, an apt assessment of the pupil helps in the accurate diagnosis of eye and neurological problems.

Clinical significance of pupillary assessment:

Each time you go for detailed eye checkup, a pupillary evaluation occurs. It helps in the assessment of critical neuro-ophthalmic and retina-related issues. This evaluation is particularly carried out in patients who possibly have increased levels of intracranial pressure (ICP). It also measures the Neurological Pupil Index (NPi), which helps in the early treatment of patients with an increased level of ICP. Therefore, it also helps in the prognosis and correct treatment of disease.

Need of measuring the pupillary diameter:

An individual’s health, the medicines, and the drugs they consume alter the pupillary diameters. People with large pupils are not fit for undergoing various eye procedures like Lasik and other refractive surgeries. Therefore, in the comprehensive pre-surgical eye assessment, pupil diameter measurement plays a crucial role.

Assessment of pupillary diameters helps in the diagnosis of diseases like Cluster headache, Concussion, and Anisocoria, etc. Knowing the significance of capillary measurements, it is, therefore, essential to measure the diameter correctly.

The Automated Pupillometer:

The NPi-300 Pupillometer is the latest technology-driven infrared digital system that helps in appropriate and accurate pupillary size measurement. Furthermore, if we measure pupil size with greater precision, then it helps to detectdiseases and potential health risks. This increased efficiency in measuring accuracy and precision, if markedly improved, can significantly improve the health of humankind. This has been achieved by the latest technology that uses a computer-based digital video system, which reduces errors.

According to a study of pupil examination with the help of automated pupillometry in clinical settling that includes pre-surgical and post-surgical evaluations, it has been found that unconscious patients had a long latency stage and a reduced constructive capillary ratio as compared to conscious individuals. Patients of liver transplant their pupil recovery graph rate was slower as compared. The automated pupillometer serves as an additional device for assessing the health status of liver transplant patients, but comprehensive studies are required.

pupil diameter measurement

What is a traumatic brain injury?

Traumatic brain injury is also called TBI or referred to as craniocerebral trauma. In simple terms, it is an acquired brain injury that causes severe damage to the brain. When the head is hit with a large force or violently by an object, the head is damaged, and the object collides with the brain tissue. The collision occurs as the skull is damaged. It can also cause permanent brain damage, external hemorrhage, coma, or it may even lead to death.

How does the pupil respond in patients suffering from a traumatic brain injury?

In the case of ordinary individuals, both the pupils of the eye are equal in size. However, in mild brain injuries like concussions and other traumatic brain injuries, the pupils become abnormal. An individual suffers from the condition termed anisocoria. The term anisocoria means that both the pupils are unequal in size.

When the light from the pupil has focused at a close distance instead of far away, the pupil further contracts. In a regular brightly lit outdoors, the size of the pupil is 3-5 millimeters in diameter. However, it changes in a dim-lit indoor area to about 2 millimeters or maybe even less than that.

Often a patient encountering a cranial injury suffers from acute pupillary dilation. But, this condition is not normal and is a neurological emergency whose treatment is necessary. This pupillary dilation causes compression of the oculomotor (third cranial nerve) and causes an effect on the brain stem also.

However, research suggests that pupillary response has to be studied in many cases, be it pupillary response in traumatic brain injury, liver transplant, or any pre-surgical procedure. Generally, the pupil size index leads us to a range of cognitive anomalies. However, multiple variations exist in the psychological literature regarding the data from pupil evaluations. Scientists are still trying to determine the relationship between the approaches to evaluate the pupil size and the data anomalies that creep up. Scientists and researchers have even used different approaches to assess pupillary response data and analyzed them. They used sexually appetitive visual content as example data and analyzed it to derive pupillary response data. These data were categorized as-

  • Unadjusted raw data
  • Percentage change data
  • Z scored data
  • Data transformed by prestimulus baseline correction

Although researchers claim that pupillary evaluation produces near-identical outcomes in most of the tests, certain systematic carryover effects are observed in specific test methods.

Therefore, examination and pupillary size measurement become essential for a broad range of comprehensive clinical diagnoses and prognoses.

Faulty measurements with a higher least count can lead to errors in treatment or medical procedures. Often ancient methods developed for pupillary evaluation may lead to unnoticed clinical problems. Therefore, technicians have harnessed the technology for an automated pupillary diameter measurement using infrared rays. These digital pupillometry devices have enhanced medical health worldwide.


New-age technology has led to the development of automated pupillometry using infrared technology. It delivers them with increased accuracy and precision, and its use should be encouraged.