An evaluation of pupil size standards used by police officers for detecting drug impairment

Optometry. 2004 Mar;75(3):175-82. doi: 10.1016/s1529-1839(04)70037-8.


Background: The Drug Evaluation and Classification (DEC) program was developed to detect, arrest, and convict drivers impaired by drugs other than alcohol. The DEC program is a training program designed to prepare police officers and other qualified persons to serve as Drug Recognition Experts (DREs).

Purpose: The purposes of this study were: (1) to determine normative values and ranges for pupillary responses using the specific DEC program protocols for pupil testing in nonimpaired persons, and (2) to appraise the suitability of the 3.0- mm to 6.5-mm pupil range as a potential sign of impairment under three conditions.

Methods: Trained DRE officers measured pupi sizes using standardized DEC protocols. Pupil measurements were taken under three light levels: room light, near-total darkness, and direct light. The subjects were 250 volunteers, with an average age of 29.2 years (+/-6.1). All subjects were healthy, nonimpaired, and free of visual, and/or neurological problems.

Results: For each pupil measured (N= 500), the mean (SD) for each of the three test conditions were: room light 3.86 (0.93) mm; near-total darkness 6.41(1.55) mm; and direct light 3.35 (0.72) mm.

Conclusions: This study determined normative values and potential ranges for pupillary responses using the specific DEC program protocols for pupil testing in non-impaired persons. When the presently approved DEC program pupil size range (3.0 to 6.5 mm) is compared with the results of this study, it appears that the DEC range for pupil size might be too sensitive. However, when determining impairment related to drug(s), the DRE reviews the results of all tests and draws a conclusion based on the totality of the evidence, not only on a variation in the pupil size.

MeSH terms

  • Adult
  • Female
  • Humans
  • Light
  • Male
  • Police
  • Pupil / physiology*
  • Reference Values
  • Reflex, Pupillary / physiology*
  • Reproducibility of Results
  • Substance Abuse Detection / methods
  • Substance Abuse Detection / standards*
  • Substance-Related Disorders / diagnosis*
  • Vision Tests / standards*