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Quantitative Pupillometry Values Are Similar in Bright Light and Dim Light Conditions
Kylie MacLean Hall1,2, Jennifer Wilson1, Ty A Johnson2
1Address correspondence and reprint requests to: DaiWai M. Olson, PhD, RN, CCRN (DaiWai.Olson@UTSouthwestern.edu).Texas Woman's University, Denton.
Background:
The recommendations to leave the lights on or turn the lights off before testing the pupillary light reflex (PLR) are primarily based on historical precedent. There is a lack of evidence to determine the best practice regarding adjusting ambient light when obtaining pupil measurements using a quantitative pupillometer (QP).
Objectives:
To examine the difference in QP measurements taken from the same subject in bright light versus in a darkened room.
Method:
Before the human subject study, light readings were obtained with a lux meter to identify the range and central tendency for light in an intensive care unit. A set of 4, paired-sample within-subjects QP measurements was obtained in alternating bright and dark rooms.
Results:
Among 32 healthy volunteers, we found neither statistical nor clinically relevant differences in the neurological pupil index score in paired observations (P = .12) taken in bright light [mean = 561.5 (37.3) lux] or dark conditions [mean = 0.9 (0.3) lux]. This remained true in a mixed model controlling for repeated observations (P = .25).
Discussion:
Pupil size was larger in dark conditions. But the finding that the pupillary light reflex functions normally despite fluctuating light levels is not unexpected.
Conclusion:
The evidence does not support a need for nurses to adjust light levels before measuring the PLR with a pupillometer.
