HealthDay News — According to a study published in JAMA Ophthalmology, regular cannabis users appear to experience a slight delay in their retinal ganglion cell (RGC) signaling.

The finding stems from preliminary research involving 52 participants, 28 of whom were regular cannabis users, defined as cannabis use at least 7 times a week. The researchers conducted neural signaling tests to compare RGC function between the regular cannabis smokers and nonsmokers.

The tests determined that regular cannabis users experienced a 10-millisecond delay in the speed with which their RGCs sent key signals to the brain via the optic nerve.

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“The conclusion that cannabis causes RGC dysfunction cannot be made with any degree of certainty based on the evidence provided in the current study,” write the authors of an accompanying editorial.

“This question should be reexamined with some urgency, using a degree of scientific rigor, which may be challenging in jurisdictions where cannabis consumption is illegal.”


Schwitzer T, et al. “Association Between Regular Cannabis Use and Ganglion Cell Dysfunction.” JAMA Ophthalmol. 2016. doi:10.1001/jamaophthalmol.2016.4761. [Epub ahead of print]

Lyons CJ and Robson AG. “Retinal Ganglion Cell Dysfunction in Regular Cannabis Users: Is the Evidence Strong Enough to Consider an Association?” JAMA Ophthalmol. 2016. doi:10.1001/jamaophthalmol.2016.4780. [Epub ahead of print]

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