Pupilometer

Pupilometer, also spelled pupillometer, is the name for two different devices used in ophthalmology — one that measures the distance between pupils, and one that measures the pupil’s response to visual stimuli.

An automated pupillometer is a portable, handheld infrared device that provides a reliable and objective measurement of pupillary size, symmetry, and reactivity through measurement of the pupil light reflex. Independent of examiner, an automated pupillometer eliminates variability and subjectivity, expressing pupil reactivity numerically so that both pupil size and reactivity can be trended for changes, just like other vital signs. An automated pupillometer also provides a reliable and effective way to quantitatively classify and trend the pupil light response.

Automated pupillometry removes subjectivity from the pupillary evaluation, providing more accurate and trendable pupil data, and allowing earlier detection of changes for more timely patient treatment. Pupil data can be automatically uploaded to the patient record, eliminating the possibility of data entry error.

The most effective way to use an automated pupillometer is to establish the earliest possible baseline measurement when the patient is admitted into the critical care unit or emergency department, and then trend for changes over time.

In the most common sense, a pupilometer is a tool for measuring pupillary distance (PD). It is used for fitting eyeglasses so that the lenses are centered in the visual axis. This is the most common nomenclature. It may also be used to verify a PD measurement taken from a millimeter ruler placed across the bridge of a patient's nose for distance and near focus.

There are a variety of ways of measuring one's pupil distance. Historically a ruler is used by optometrists. State of the art are video centration devices which provide higher accuracy and repeatability compared to manual measurements. The accuracy is especially a concern for progressive lenses where small deviations severely reduce the performance of the lens. In addition to having it measured when one visits an optometrist, there are a variety of mobile phone apps and web apps that a person can use. The apps are available for the iPhone, iPod touch, and iPad. The web app is used by a variety of online sellers of eyeglasses. In order to use the phone app or web app, a camera and a credit card with a magnetic strip are needed to assist in the measuring processes.

Alternatively, a pupilometer is a type of pupil response monitor — a monocular device measuring the amount of dilation of the pupil in response to a visual stimulus.

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Wikipedia