Presented December 12-15, 2002 San Diego CA
Scientific Program American Academy of Optometry
Author: Jack Richman, OD, FAAO, FCOVD
The New England College of Optometry
Co-author(s) Roberto S. Noriega
THE SENSITIVITY AND SPECIFICITY OF INFRARED PUPILLOMETRY MEASUREMENTS IN IDENTIFYING DRUG IMPAIRMENT IN A COUNTY PROBATION PROGRAM
Author: Jack Richman Affiliation: The New England College of
Optometry
Co-author(s) Roberto S. Noriega , San Diego County Dept. of Probations
Introduction:
In California, there are approximately 600,000 probationers within the criminal justice system. Drug testing is an important tool to reduce health and workplace costs and to monitor criminal offenders. Unlawful drug use is a violation of the conditions of probation and periodic drug testing is an effective method to deter and to detect drug use. Unlike most forms of misconduct, it leaves a chemical trace that can be detected reliably by relatively inexpensive tests. San Diego and Los Angeles have fairly elaborate testing programs, but neither tests more than a small proportion of its clients. 1
Frequent testing is essential to reducing the rate of drug
use. Once-a-week testing produces about a 35% chance of detecting
any given incident of drug use. Industry and law enforcement,
e.g., probation departments, employ drug screening to check for
drug free compliance. Drug testing (urinalysis ) itself is relatively
low-cost, between $5 and $10 per test. However, when such testing
is performed thousands of times per month, the cost may be quite
costly and possibly prohibitive for an effective compliance program.
An alternative or adjunct approach may utilize newer noninvasive
physiological methods that measure impairment. These may be more
efficient and less costly than urinalysis. One such method is
pupillometry. Alterations in pupillary reactions have been shown
to be related to the presence of drugs. 2,3.4. The use of photographic,
videographic, and/or infra-red pupillometry has been employed
experimentally and commercially for the detection of physiological
impairment. 5-10
If an alternative or adjunct approach, e.g., infra-red pupillometry,
to measure impairment can be demonstrated to be effective, then
more effective compliance in monitoring probationers may be achieved.
Purpose: The objective of this pilot program was to determine the sensitivity and specificity of a commercially available pupillometer to detect possible impairment due to drugs when compared with urinalysis.
Methods:
Subjects :
The subjects were defendants on probation with the San Diego County
Dept. of Probation in San Diego County, California. Participating
were one hundred forty six subjects, aged 18-50 years (Mean 34.3(10.2)
years ) with 72% male and 18% females . These subjects were on
a frequent drug testing schedule ranging from weekly to monthly.
They were tested on a random basis. Each one was given instructions
to call a recorded message each night and to listen for a color,
assigned to them by staff. When their color came up, they were
instructed to report to the probation office for testing the next
day. Each subject was tested at least once .
Method
When tested, each subject received two procedures for possible drug impairment: (1) the standard urinalysis, using the Gas Chromatography Mass Spectrum (GCMS) method to determine the presence of drugs, and (2) measurement of pupillary responses by a trained probation staff member using the MCJ Inc. Eye Check™ infrared pupillometer .
Pupillometer Procedure:
At the beginning of each test, a verbal survey was conducted.
Subjects were asked several screening questions: (1) Informed
consent and permission to participate in the study, (2) Had they
ever suffered a serious head or eye injury, and(3) their age.
Before a subject was deemed suitable for screening, personal and
historical information was entered into the Eye Check™ computer
program. Information entered included; identification number,
probation officer's name, age, nationality and any other pertinent
information, such as medications taken. When all of the information
was entered, the subject was instructed to pickup the Eye Check™
Pupillometer instrument. The instrument weighs approximately 2
lbs. and is held similar to a pair of binoculars with peripheral
eye shields to exclude light. (Figure 1). They are instructed
to look into it, and focus on a red crosshair with the eye being
tested. (Figure 2)
At the start of each test, subjects were told not to remove
the instrument from their eyes until instructed to do so at the
end of the test. During a thirty second adaptation to the dark,
the participants were told that they would see a series of three
green flashing lights with five second intervals, between each
flash. The subjects were told that they could blink as needed
during the dark adapt time period and between flashes. To further
clarify the instructions, subjects were told that they would be
instructed when to blink and not to blink. Other instructions
given were; do not chew gum, do not speak and remain as still
as possible during the test. The instrument and software tracks
the pupil's reaction response to a light stimuli. The pupillary
dynamics are collected, recorded, and stored.
Based on the proprietary algorithms in the Eye Check™ software
which is measuring the initial pupil diameter, a controlled flash
of light , the light reflex reaction including the time to initiate
the pupil constriction, the length of time to full constriction,
the final pupil diameter, and the change in pupil size from the
dark to light condition, a determination of possible drug impairment
vs. normal is made. The data is then processed and the results
are displayed on your computer screen. The displayed data indicates
a PASS/FAIL results.
Results: The objective of this investigation was to determine the sensitivity and specificity of a commercially available pupillometer to detect possible impairment due to drugs when compared with urinalysis. In this study, the sensitivity and specificity of the Eye Check™ pupillometer in detecting potential presence of drugs was determined. The presence or absence of a pharmacological agent was confirmed with urinalysis employing a comprehensive drug screen (GMSA). The drugs identified by toxicological evaluation included marijuana, stimulants, including amphetamine, cocaine, tranquilizers, and opiates, including heroin.
Applying the positive vs. negative for impairment criteria
and scores as part of the analysis software by the manufacturer,
the sensitivity and specificity of the Eye Check™ pupillometer
was assessed. The results were based on a total 126 subjects since
approximately fourteen percent of the tests conducted on the original
146 subjects were inconclusive on the Eye Check™ due to various
reasons, e.g., defendant's history of drug abuse, prescribed
medications, medical conditions, and operator training. Of these,
sixty-five percent were negative for drugs or impairment on the
Eye Check™ Pupillometer and urine screen. Fifteen percent
of the tests conducted were positive on both the Eye Check™
Pupillometer and urine screen for a variety of drugs. Seventeen
percent were considered false positives on the Eye Check™
and three percent were considered false negative.
Based on this, The Eye Check™ appears to differentiate
subjects who were potentially drug impaired from normal in the
majority of cases. The sensitivity was 86.2% and the specificity
was 78.85%.
Discussion:
It should be noted that many subjects tested were under the care of physicians and were occasionally prescribed pain and or psychotropic medications. These prescribed drugs may have impacted the results of the pupil tests. The Eye Check™ system rated these tests as positive where urine screening was designed to ruled out the presence of higher dosage level street drugs.
What was the economic and drug free compliance outcome in this study? Based upon the first five months of this fiscal year it is projected that the San Diego County Probation Department will have conducted over 48,000 urine tests. The cost of a five panel urine toxicological screening test is $6.55. The estimated total cost for five panel drug screens a year is over $300,000. In this study, it was found that 65% of the probation subjects were identified with the Eye Check™ Pupillometer as non drug impaired and confirmed with urine drug tests. Using the pupillometer solely, the Probation Department could have saved more than half of the drug test expenditure. These funds could have been applied to more frequent testing and drug free compliance which is essential to reducing the rate of drug use.
Why is there a potential difference between the presence of measurable impairment, e.g., pupils, and the presence of a chemical substance , e.g., urinalysis. Drugs create impairment in various central nervous system functions. It may be exhibited in various ways in an impaired individual e.g., slurred speech, bloodshot eyes, difficulty balancing and walking. Many drugs, e.g., cocaine, opiates, alcohol, and marijuana, have short duration of their effects . It is during that period of the activity where the impairment is apparent. When the drug has worn off, the signs of the impairment are gone or have diminished significantly . However, the presence of a drug or drugs in urine does not provide information as to whether the individual is actually under the influence of the particular drug at that time unless impairment is measured concurrently Likewise, no determination can be made from urine as to the amount of or the time of the dose. For example, when smoked, the effects of cannabis begin almost immediately. The effects of smoked cannabis peak after about 20 minutes and last for 1-2 hours, however, the presence of cannabis metabolites may be present in the urine for 24 to 72 hours from a single use.
Consequently, the presence of the drug in the urine does not necessarily indicate impairment. It is fully possible to have a positive toxicological result without any sign of impairment. This was evident in several subjects in this study. As long as this discrepancy is recognized, the use of physiological based tests of impairment when compared with toxicological results will have appropriate meaning to the examiner.
Conclusions: The Eye Check™ pupillometer appears to effectively differentiate drug impaired subjects from normals in this study. The fifty-six percent identified as non drug impaired represents the number of subjects that could have been tested using the pupillometer alone yielding significant economic savings and probation staff time. Pupillometry has demonstrated its value as a tool in screening for drugs . Overall, it appears to be a valid and cost effective tool for its intended purpose . It requires minimal training to operate, is portable, and is adaptable to a variety of drug testing and screening programs. Further familiarization with the instrument, improved differential algorithms, and improved training in its use will most likely increase its sensitivity and specificity.
References:
1. Kleiman MR. Tran HR, Fishbein P. Opportunities and Barriers
in Probation Reform:A Case Study of Drug Testing and Sanctions.
California Policy Research Center B r i e f: Vol. 14, No. 4 June
2002
2.Tennant F. The rapid eye test to detect drug abuse. [Journal
Article] Postgraduate Medicine. 84(1):108-14, 1988 Jul.
3. Kosnoski EM. Yolton RL. Citek K. Hayes CE. Evans RB. The Drug Evaluation Classification Program: using ocular and other signs to detect drug intoxication. [Review] [17 refs] [Journal Article. Review. Review, Tutorial] Journal of the American Optometric Association. 69(4):211-27, 1998 Apr
4.Linzmayer L. Fischer G. Grunberger J. [Pupillary diameter and pupillary reactions in heroin dependent patients and in patients participating in a methadone and morphine replacement program]. [German] [Journal Article] Wiener Medizinische Wochenschrift. 147(3):67-9, 1997.
5. Grunberger J. Linzmayer L. Cepko H. Saletu B. [Dynamic light-evoked pupillometry for the differentiation of psychotropic substances]. [German] [Clinical Trial. Controlled Clinical Trial. Journal Article] Arzneimittel-Forschung. 37(3):357-60, 1987 Mar.
6. Murray RB. Loughnane MH. Infrared video pupillometry: a method used to measure the pupillary effects of drugs in small laboratory animals in real time. [Journal Article] Journal of Neuroscience Methods. 3(4):365-75, 1981 Apr.
7. Irene E. Loewenfeld, The Pupil - Anatomy, Physiologie and Clinical Applications, 2223pp,Butterworth-Heinemann, ISBN 0750671432,
8. Priemer, H.Sachs, The compact integrated pupillograph CIP(AMTech)
- its value on detection of psychophysical disorder caused by
drugs, Abstract 219: 15th International Conference on Alcohol,
Drugs,
and Traffic Safety, T2000, Stockholm 2000
9. PMI, Inc. FIT 2000 Fitness-for-Duty Impairment Screener
5951 Halpine Road Rockville, MD 20851
10. Final Report: Use of the EyeCheck (T) pupillometer technology effectiveness as a noninvasive technique to detect and measure possible impairment resulting from the suspected usage of alcohol, drugs ,and/or detect fatigue from sleep deprivation. Illinois State Police. Springfield IL. Jan 2001
EFFECTS OF ANTIDEPRESSANTS ON THE HUMAN PUPIL
E. Szabadi and C.M. Bradshaw 24th Pupil Colloquium
http://www.jiscmail.ac.uk/files/PUPIL/ca.htm
http://www.jiscmail.ac.uk/files/PUPIL/col22abs.htm
http://www.jiscmail.ac.uk/files/PUPIL/absbook.htm23rd Pupil Colloquium,
held in Nottingham, U.K. in August 1999
Kühner, S. Meister, R.D. Hilgers, M. Diestelhorst, The Circadian Rhythm of the pupil in healthy volunteers, Abstract: JOVS, March 13, 1998 Vol. 39, No.4, 2225-B82