The Prevalence of Relative Afferent Pupillary Defects in Normal Subjects

Abstract

Observation and pupillographic measurements of the swinging light test in a large normal subject cohort has confirmed that an RAPD is present in a small minority but that it does not exceed 0.39 log units. The RAPD in these subjects may be explained by inaccuracy of measurement or by asymmetries in the connections between visual pathways and pretectal nuclei in the midbrain.

The pupillary light reflex pathway

“…Since there are six patients with a RAPD of 0.3 log units, it cannot be attributed to a normal pupillary system in more than one of the six cases and it seems therefore rather unlikely that RAPDs of 0.3 log units occurred independently of the brain lesion. 51 The fact that the RAPD in the present study as well as in previous ones was always located contralateral to the brain lesion further supports the belief that its presence is not coincidental. 18…”

“…In a recent study, a RAPD of 0.3 log units was present in 2 of 102 healthy subjects. 51 Higher RAPDs were not found in the sample. These results, that were derived from a large number of normal subjects and were confirmed by means of modern pupillography, support the use of the threshold of 0.3 log units as a pathologic limit.…”

First results of automated RAPD-SWIFT method in dynamic pupillometry

“…The size of the error bars on the PupilX measured data points is consistent with the statement that measurement steps finer than 0.3 log-units are not necessary: as noted by Wilhelm et al [4]: 'Kawasaki et al [. .…”

“…This SWIFT system was used in 2007 by the Tübingen group to establish the range of RAPD values present in a sample of 102 normal subjects [4] in order to compile a representative sample of normative data.…”

“…7) The paragraph has been rewritten with the suggested rewording of the first sentence and also to clarify the origin of the quoted statement (the statement is from the 2007 Wilhelm paper, reference [4]). …”