Exploring the Latest Developments in Pupillometry Exams

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Automated pupillometry has dramatically improved pupillometry exams. This new technology has taken pupil examination from a cumbersome diagnostic tool with a high user error rate to a quick, accurate exam that helps diagnose multiple medical conditions. With the accelerating use of automated pupilometers, many are left wondering, what's new with pupillometry exams? 

If you are curious about the latest advancements in pupillometry, keep reading. This blog post discusses how to conduct a pupil exam, why technology improves pupil exams, and how to properly bill for automated pupillometry.

What is a Pupillometry Exam, and What Does it Measure?

A pupillometry exam is a simple, non-invasive procedure used to measure the size and reactivity of the pupils in response to light. It is a tried and true medical exam used for centuries to assess eye health and neurological conditions. There are three assessments included in a pupillometry exam:

  • Integrity of the pupillary light reflex pathway
  • The light near dissociation
  • The presence or absence of a relative apparent pupillary defect

Pupil Structure and Function

The pupil is the aperture of the eye located in the center of the iris. It is equal in size, round and black in color. Its primary function is to regulate the amount of light that penetrates the eye. As light enters the eye, it passes through the lens before being relayed onto the retina, where the image is processed and formed. The pupil appears black because the inner eye is void of light.

The pupil's size alters to enhance our eyesight. A constricted pupil gives us a more distinct, broader depth of field, while a dilated pupil enhances our ability to perceive even the dimmest of stimuli. Changes in pupil size rely on a series of nerve pathways between the retinas, the optic nerves, and the brainstem. Evaluating these pathways through a pupillometry exam provides valuable information about eye health, optic nerve function, and general neurological state.

History of the Pupillometry Exam

The swinging flashlight test is the traditional method for conducting the pupillometry exam. As eye care professionals know, this method is cumbersome and relies on subjective observations. To complete the exam, the practitioner evaluates the pupils’ light reflex in a dimly lit environment and records their responses using a standardized pupil assessment size chart.  This method is prone to user error. Thankfully, advanced technology has provided an alternate method that is standardized, accurate, and easy to perform. 

Why Automated Pupillometry is Better

Automated pupillometry allows practitioners to quickly and objectively detect pupil abnormalities. Since it uses technology, it takes the guesswork out of pupillometry measurements. The information obtained is more accurate than the swinging flashlight test because it does not require subjective observations. Furthermore, it requires less training and can easily take place by a trained technician before the patient sees the provider and has their eyes dilated.

There are two sub-categories of automated pupillometry: infrared videography and computerized pupillometry. Infrared videography is especially useful in patients with dark irises. The exam is administered in the dark, and the melanin, which makes the irises dark, reflects the infrared light. As a result, the pigmented irises appear light on the screen, making the black pupils stand out. 

In contrast to infrared videography, technicians can perform computerized pupillometry in dark and light environments. Healthcare professionals use the exam to gather information about how movement, color, and visual acuity affect the pupillary light reflex. It provides detailed, accurate information without a cumbersome pupil assessment size chart. Furthermore, it gives immediate results, enabling providers to make quick, informed assessments.

What Does Pupillometry Help Diagnose?

The physiologic basis of pupillometry exams is that the pupils' reaction to light is linked. In a standard exam, the pupils reflexively constrict in response to bright light. Shining a light into one eye causes an equal constriction in both eyes. This response is called the consensual light reflex. An abnormal pupillary light response indicates a problem with the optic nerves or the retinas and neurological conditions. 

Pupillometry helps diagnose multiple health conditions affected by the optic nerve or retina and is part of the field vision test for glaucoma. An abnormality on a pupillometry exam indicates the patient has a relative afferent pupillary defect (RAPD). RAPD is a condition in which there are alterations in the pupils' response to light. In patients with RAPD, a stimulus shown in one eye does not elicit a consensual light reflex. RAPD is an expected finding in patients with optic nerve disease - ischemia, compression, etc.

In addition to helping diagnose problems with the optic nerve or retina, Lasik surgeons use new visual field machines and automated pupillometry measurements as screening tools for potential postoperative complications. The American Society of Cataract and Refractive Surgery (ASCRS) underscores the significance of automated pupillometry, advocating its use for every patient considering LASIK surgery. Why? This suggestion is born out of studies observing that individuals with bigger pupils are more prone to experiencing night vision disturbances after undergoing Lasik surgery.

Automated pupillometer exams in the intensive care unit (ICU) are also common practice. ICU practitioners use automated pupillometry to help diagnose neurologic complications in traumatic brain injury patients. New onset, un-reflexive anisocoria, or pupil dilation, indicates intracranial hypertension, often preceding brain herniation. Standardized measurement of pupil response to light may help identify patients at risk for neurological deterioration.

Billing and CPT Code for Pupillometry

As of January 1, 2023, there is a new billing code for quantitative pupillometry: 95919. This CPT code allows practitioners to bill for automated pupillometry examinations. To qualify for payment, a licensed provider must interpret both unilateral and bilateral results and document the findings in the patient's medical record. 

The addition of a new CPT billing code for quantitative pupillometry highlights the importance of automated pupillometry technology. This technology makes pupillometry exams more accurate and reliable. The ease of this technology provides optometry and ophthalmology professionals with valuable diagnostic information about eye health and optic nerve function. It can be used in various healthcare settings, from outpatient clinics to the ICU. 


Broadway, D. C. (2012). How to test for a relative afferent pupillary defect (RAPD). Community Eye Health. 25(79-80), 58-9.

Kalayoglu, M. V. (2005, March 30). Computerized pupillometry: From a research tool to clinical diagnostics. OphthalmologyWeb. 

Sandroni, C., Citerio, G., & Taccone, F.S. (2022). Automated pupillometry in intensive care. Intensive Care Medicine, 48, 1467–1470. 

Tomy, R. M. (2019). Pupil: Assessment and diagnosis. Kerala Journal of Ophthalmology, 31(2), 167.

Vejdani, A., Ameri, M., & Al-Zubidi, N. (2023, April 6). Relative afferent pupillary defect. American Academy of Ophthalmology.

About Virtual Field

Virtual Field delivers an exceptional eye exam experience. Eye care professionals including ophthalmologists and optometrists examine patients faster, more efficiently, and more comfortably than ever before. Exams include Visual Field, 24-2, Kinetic Visual Field (Goldmann Perimetry), Ptosis, Esterman, Color Vision, Pupillometry, and more.

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