September 27, 2023

My Henessy

Masters of Health

How to Examine Pupils?

5 min read
PERRLA Eyes, Medical Abbreviation, Meaning, What It Stands for

The quantity of light that enters your eyes is controlled by the size of your pupils. When doing a full eye exam for a pupillary response in traumatic brain injury, it is critical to check the pupils for any abnormalities. A pupil test, which is performed since you do not have voluntary control over your pupils, may reveal probable abnormalities with your autonomic nervous system and other disorders throughout your body.

The Pupil

This circular black circle located in the middle of your iris, which is the colorful portion of your eye, represents your pupil. Light enters the eye via the pupil, which serves as a hole for light to travel through to the retina, which is a light-sensitive layer located at the rear of the eye. Similar to a camera aperture, the pupil may be adjusted to let more or less light into the camera depending on your preferences.

The pupil may dilate (enlarge) or contract (constrict), depending on the situation. When exposed to external stimuli, the muscles of your iris contract, allowing you to regulate the quantity of light that reaches your retina. When exposed to intense light, the pupil constricts in order to minimize the amount of light that enters the pupil. It is necessary for the pupil to dilate in order to let more light into the eye, which improves vision in low light or complete darkness or dim light.


Anisocoria is the first thing your doctor will check for when examining your eyes. When the pupils are not the same size, you have anisocoria. Anisocoria is normal in 20% of the general population and does not indicate any abnormality. Uneven pupil sizes may be an early warning indication of a more severe illness, though.

In both bright and low light, your healthcare practitioner is assessing the size and shape of your pupil. It’s also possible to observe the speed and quality of the pupil’s reaction to various stimuli. Near stimuli, such as tiny print, may also be used by your practitioner to measure the response of your pupils to these stimuli.

The pupil is regulated by a neural route that travels across the body for a considerable distance. Starting in the brain and traveling via the spinal cord, subclavian artery, neck, and brain extensions, a nerve regulates the pupil’s size before reaching the optic nerve and eventually reaching the pupil. Its nerve and the pupillary response might be affected by any obstruction in this route.

pupillary light reflex is measured by eye specialists using three different approaches: 

Light Response Pupil Test

During the light response pupil test, a person’s pupil size is measured in relation to light exposure. Before asking you to focus on an item in the distance, your healthcare professional will lower the lighting. From both sides, a beam of light will be directed into your eyes. Your practitioner will pay special attention to the size and shape of your pupils and record whether or not they constrict in reaction to light.

Swinging Flashlight Pupil Test

Pupils are compared using the swinging light pupil test. Your eyes will once again focus on a distant object when the lights are dimmed in the room. Each time your doctor moves the light from one eye to the other, he or she will take note of the reaction of each pupil. When a bright light is put into your eyes, your pupils should either constrict or remain unchanged in size.

The Marcus Gunn pupil, also known as an afferent pupillary defect (APD), may warn your doctor of a more severe issue to your pupil reactivity that may be caused by an optic nerve or neurological problem, such as pupil dilation following the introduction of light stimulus on the swinging flashlight test.

  1. Near Response Pupil Test

Pupils are tested for their responsiveness to a nearby target using the close response pupil test.

A room with regular lighting will be used for this test. Patients are asked to stare at a distant object than to move a small item or card in front of their eyes. In order to make sure that your pupils swiftly contract as your fixation shifts from far to near, your practitioner will attentively monitor your pupils while you fixate your eyes on the near item.

This is a rare test that is only ordered when a specific condition is being investigated or ruled out, but it is critical.

Pupil Size and Your Health

Your healthcare professional may learn a lot about your health just by looking at the size of your pupil. If you don’t use it, you may miss out on potentially life-threatening medical disorders.

The pupil is one of the eye’s many intricate components. In order to keep light out of your eyes, you need to use this. It’s also constantly expanding and contracting.

As the light around you becomes brighter or darker, your pupil automatically expands or contracts to match the intensity. If you’re gazing at nearby or far away items, the sphere shrinks or grows.

Testing Pupil Size

Anisocoria, an eye disorder in which the pupils are not the same size, is the first thing your doctor will check for when examining your eyes. Approximately 20% of the general population has a mild anisocoria, which does not indicate any abnormalities. However, in certain circumstances, droopy pupils may be a sign of a more severe illness.

You’ll have your pupils measured in both bright and low light by your doctor. The quality and speed with which your pupils adapt to bright and dim light will be noted by your healthcare experts as well. They may also use adjacent things, such as little text, to gauge your students’ receptivity. It is also noted whether there are any disparities amongst your students.

Oculomotor and optic neurons work together to regulate pupil size. The autonomic nervous system sends some of these instructions to these nerves. All of your bodily functions, many of which are automatic, are controlled by this section of the nervous system.

Your pupils’ reactivity and pupillary light reflex to stimuli may alter if your autonomic nervous system is disrupted. Because of this, the size of your pupils might suggest health issues that have nothing to do with your eyes.