Panel discusses how to detect relative afferent pupillary defects
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WAIKOLOA, Hawaii — Andrew G. Lee, MD, showed multiple ways to detect relative afferent pupillary defects in the practice during a panel discussion at Hawaiian Eye 2022.
Lee, the chair of the Department of Ophthalmology at Houston Methodist Hospital, said a relative afferent pupillary defect, or RAPD, can occur in either eye.
Lee touched on small pupils and big pupils. “What if this is a dangerous pupil? How do I recognize it? When do I triage it, and how do I refer it?”
Showing an image of a pair of eyes with a larger pupil in the right eye, Lee questioned on which side the lesion would appear.
According to Anthony C. Arnold, MD, the chief of neuro-ophthalmology at UCLA Stein Eye Institute, the lesion would be on the right side.
However, the lesion could be on either side, Lee said.
“Yes, and that's because the pathway crosses at the chiasm,” Lee said. “Actually, more fibers cross at the chiasm, 53 to 47. Your temporal field is actually slightly bigger than your nasal field, and so, if you have an optic tract lesion, the RAPD might be on the contralateral side.”
Lee then asked Prem S. Subramanian, MD, PhD, the vice chair for academic affairs and division head of neuro-ophthalmology at the Sue Anschutz-Rodgers UC Health Eye Center in Aurora, CO, if he had ever seen an RAPD in a cataract.
“You should not see an RAPD just from a cataract,” Subramanian said. “I think, paradoxically, sometimes the cataract scatters the light so much you can see the RAPD in the other eye, but that is one of those weird things. The book answer is no.”
Moving to the next topic, Lee said if there is an RAPD, track lesions are almost always compressive. Then, he asked Grant T. Liu, MD, the Raymond G. Perelman Endowed Chair in pediatric neuro-ophthalmology at the Children's Hospital of Philadelphia, if he had ever seen a non-compressive track.
“Yes, I've seen ischemic lesions,” Liu said. “It’s rare, but it happens.”
Lee said this would be a “subtle” RAPD that if you did not know you were supposed to look for, you would most likely miss it, much like cataract contralateral.
“You only need one working pupil, but you need two optics to detect an RAPD,” Lee said.
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Lee AG. What if... the pupil showed this? Presented at: Hawaiian Eye; Jan. 15-21, 2022; Waikoloa, Hawaii.
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