Genetic advances in ophthalmology: The role of melanopsin-expressing, intrinsically photosensitive retinal ganglion cells in the circadian organization of the visual system

David J. Ramsey, Kathryn Moynihan Ramsey, Demetrios G. Vavvas*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Daily changes in the light-dark cycle are the principal environmental signal that enables organisms to synchronize their internal biology with the 24-hour day-night cycle. In humans, the visual system is integral to photoentrainment and is primarily driven by a specialized class of intrinsically photosensitive retinal ganglion cells (ipRGCs) that express the photopigment melanopsin (OPN4) in the inner retina. These cells project through the retinohypothalamic tract (RHT) to the suprachiasmatic nuclei (SCN) of the hypothalamus, which serves as the body's master biological clock. At the same time, the retina itself possesses intrinsic circadian oscillations, exemplified by diurnal fluctuations in visual sensitivity, neurotransmitter levels, and outer segment turnover rates. Recently, it has been noted that both central and peripheral oscillators share a molecular clock consisting of an endogenous, circadian-driven, transcription-translation feedback loop that cycles with a periodicity of approximately 24 hours. This review will cover the role that melanopsin and ipRGCs play in the circadian organization of the visual system.

Original languageEnglish (US)
Pages (from-to)406-421
Number of pages16
JournalSeminars in Ophthalmology
Volume28
Issue number5-6
DOIs
StatePublished - Sep 2013

Keywords

  • Circadian photoentrainment
  • Intrinsically photosensitive retinal ganglion cells
  • Melanopsin (OPN4)
  • Molecular clock
  • Retina

ASJC Scopus subject areas

  • Ophthalmology

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