There are two different components to the inaccuracies in manual pupillary measurements.  One is the interexaminer consistency, and the other is the precision of measurement.  The interexaminer inconsistency makes it difficult to detect early or small changes.  The pupillometer serves as a quantitative standard that solves both problems.  Because it is a mechanical measurement, there is minimal interexaminer variability and higher sensitivity in detecting pupillary reaction.  Thus, the pupillometer may be a useful tool in future studies that use the pupillary examination to predict clinical outcomes or radiological findings.