Automated pupillometers: Not just for eye care professionals

May 24, 2013
NeurOptics NPi-100 pupillometer

NeurOptics NPi-100 pupillometer

By Geoffrey W. Goodfellow, O.D., and Dominick M. Maino, O.D.

Automated handheld equipment can be an important resource for optometrists in gathering information about patients’ vision and health. Such devices are particularly helpful in working with children or patients who have physical limitations in aligning their head inside more traditional table-top instrumentation. Many eye care professionals already rely on automated devices to measure such things as intraocular pressure, blood pressure, or refractive error. Now, a new generation of handheld automated pupillometers is proving useful in evaluating both eye problems and systemic conditions from head trauma to Parkinson’s.


Most practices also make use of a handheld pupillometer to determine monocular pupillary distances, which are essential when fitting progressive addition lenses. However, less common in optometry is the use of pupillometers that also measure pupil size.

Although all comprehensive eye examinations include measuring the pupils’ response to a pen light or transilluminator, the standard pupil gauge is still a common method when it comes to measuring pupil size.

Handheld automated pupillometers provide a more standardized measurement of pupil size, and some are even able to evaluate the pupil size under scotopic, low mesopic, and high mesopic light conditions.

Knowing the pupil size in varying light levels is particularly important for patients considering refractive surgery or multifocal intraocular lenses. A patient with good vision at one light level may experience halos, glare, or blurred vision if the pupil size changes considerably.

The devices are also able to provide a more objective measurement of the pupillary light reflex. The results can be displayed on an LCD screen to provide a numeric indication of whether the pupillary response is normal or not.

This is helpful because manual pupillary assessment has been characterized by larger inter-examiner variability.

Outside of eye care

Pupillometers are already used by other professionals. Such devices have become helpful to doctors evaluating head trauma, and some studies show that pupillary reactivity can be used as an early indicator of increased intracranial pressure.

Doctors are also using automated pupillometry to evaluate rheumatoid arthritis, lupus, Parkinson’s disease, sleep disorders, or even diabetes, all of which may cause differences in pupil size or reactivity.

Pracitioners are also conducting automated pupil examinations on patients undergoing physical exams to become policeman and firemen. Pupil abnormalities can reveal narcotic influence or progressive joint disorders that could disqualify candidates for those professions.

A more recent benefit of pupillometer use has been in detecting the light reflex during cardiopulmonary resuscitation.

The presence or absence of the pupillary light reflex following CPR has shown to have some prognostic value.

In a 2012 study, a NeurOptics NPi-100 pupillometer was used to measure the light reflex of 30 cardiac arrests requiring resuscitation at the University of California San Francisco Medical Center.

The study, published in the journal Resuscitation, found continuous presence of a light reflex or absence for less than five minutes during resuscitation was associated with early survival of the code and a good neurological outcome.

In contrast, no patients without a light reflex or with a gradually deteriorating light reflex survived the code, and absence of a pupillary light reflex for more than five minutes was associated with an unfavorable outcome, the researchers found.


As optometrists, we might consider the use of handheld automated equipment involving the eyes to be mainly the purview of the eye care practitioner. However, this same technology may also be helpful to other professionals.

The recent research has begun to draw interest in the potentials of automated pupillometry in a range of health care disciplines.

Practicing optometrists should be considering now how to provide patients a full range of the benefits automated pupillometry can potentially offer. Moreover, we should be ready to help other health care professionals understand this technology.

The views expressed are those of the author and do not necessarily reflect the views of the AOA. Geoffrey G. Goodfellow, O.D., is an associate professor of optometry at the llinois College of Optometry (ICO), ICO’s assistant dean for Curriculum and Assessment and the president of the Illinois Optometric Association. He can be contacted at ggoodfel@ico.edu. Dominick M. Maino, O.D. is a professor of pediatrics and binocluar vision at ICO and a Distinguished Practitioner of the National Academies of Practice. He can be contacted at dmaino@ico.edu.

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