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Invited Commentary
January 2017

Retinal Ganglion Cell Dysfunction in Regular Cannabis Users: Is the Evidence Strong Enough to Consider an Association?

Author Affiliations
  • 1Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
  • 2Department of Ophthalmology, British Columbia Children’s Hospital, Vancouver, British Columbia, Canada
  • 3Department of Electrophysiology, Moorfields Eye Hospital, London, United Kingdom
  • 4Institute of Ophthalmology, University College London, London, United Kingdom
JAMA Ophthalmol. 2017;135(1):60-61. doi:10.1001/jamaophthalmol.2016.4780

Cannabis is widely used, and over the last decade, this drug has been legalized in several jurisdictions. Many others are considering this change. While public information and road safety campaigns have consistently focused on alcohol, cannabis-related toxicity has been relatively neglected as a public health issue. Further, rigorous investigation of this drug is therefore timely and appropriate.

We read with interest the study by Schwitzer et al1 in which the pattern electroretinogram (PERG) was used as a measure of retinal ganglion cell function. They conclude that regular use of cannabis is associated with a delay in the PERG N95 component and infer this represents delayed transmission of action potentials from the retina to the visual cortex. However, shortcomings in the study design, methods, and data analysis, acknowledged in part by the authors, weaken their conclusions.