Chromatic Pupillometry Findings in Alzheimer’s Disease

Martina Romagnoli, Michelangelo Stanzani Maserati, Maddalena De Matteis, Sabina Capellari, Michele Carbonelli, Giulia Amore, Gaetano Cantalupo, Corrado Zenesini, Rocco Liguori, Alfredo A. Sadun, Valerio Carelli, Jason C. Park, Chiara La Morgia

Research output: Contribution to journalArticlepeer-review

Abstract

Intrinsically photosensitive melanopsin retinal ganglion cells (mRGCs) are crucial for non-image forming functions of the eye, including the photoentrainment of circadian rhythms and the regulation of the pupillary light reflex (PLR). Chromatic pupillometry, using light stimuli at different wavelengths, makes possible the isolation of the contribution of rods, cones, and mRGCs to the PLR. In particular, post-illumination pupil response (PIPR) is the most reliable pupil metric of mRGC function. We have previously described, in post-mortem investigations of AD retinas, a loss of mRGCs, and in the remaining mRGCs, we demonstrated extensive morphological abnormalities. We noted dendrite varicosities, patchy distribution of melanopsin, and reduced dendrite arborization. In this study, we evaluated, with chromatic pupillometry, the PLR in a cohort of mild-moderate AD patients compared to controls. AD and controls also underwent an extensive ophthalmological evaluation. In our AD cohort, PIPR did not significantly differ from controls, even though we observed a higher variability in the AD group and 5/26 showed PIPR values outside the 2 SD from the control mean values. Moreover, we found a significant difference between AD and controls in terms of rod-mediated transient PLR amplitude. These results suggest that in the early stage of AD there are PLR abnormalities that may reflect a pathology affecting mRGC dendrites before involving the mRGC cell body. Further studies, including AD cases with more severe and longer disease duration, are needed to further explore this hypothesis.

Original languageEnglish
Article number780
JournalFrontiers in Neuroscience
Volume14
DOIs
Publication statusPublished - Aug 11 2020

Keywords

  • Alzheimer’s disease
  • chromatic pupillometry
  • melanopsin retinal ganglion cells
  • post-illumination pupil response
  • pupil
  • pupillary light reflex

ASJC Scopus subject areas

  • Neuroscience(all)

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