Isolated Relative Afferent Pupillary Defect Secondary to Contralateral Midbrain Compression

The pupillary light reflex pathway

“…This assumption is strengthened by several cases of a RAPD with normal visual function in lesions close to the LGN or pretectal region as well as by reports of optic tract lesions without a RAPD. 4,28,[37][38][39][40][41][42][43][44] The present findings also support the concept of cortical input into the PLR (figure 3), which may enter the PLR pathway via the area depicted in figures 1B and 2. Therefore, disturbed processing of signals along this part of the geniculostriate pathway can lead to a RAPD.…”

Rapid diagnosis of retina and optic nerve abnormalities in canine patients with and without cataracts using chromatic pupil light reflex testing

“…However, we cannot exclude the possibility that focal chorioretinitis, which we have observed in the majority of our optic neuritis patients, resulted in the primary rod damage and impairment of retinal electrical activity and night vision. Many optic neuritis patients may have inflammatory brain component affecting predominantly the white matter, so it is possible that observed lack of the PLR and dazzle reflex may be a result of the damage to subcortical mid‐brain centers and/or their efferent radiations, which could potentially contribute to the absence of these reflex responses 36–39 …”

Relative afferent pupillary defect with normal vision and vertical strabismus—implications for pupillary pathway anatomy

“…Quantification of an RAPD as >0.3 log is therefore important to demonstrate that an RAPD is pathologic, especially in the absence of visual impairment. Eight such cases have been published between 1984 and 2004 [4], only three of which included explicit quantification of the RAPD [5,6,8]. All eight cases were caused by a tumour or haemorrhage in the dorsal midbrain.…”