Purchase this article with an account.
Rima Patel, Adnaan Zaffer, Alma Ramic, Kenzie Preston, Bruce Gaynes, Christopher Stefonowicz; Functional Correlates of Intrinsically Photosensitive Retinal Ganglion Cells among Individuals Exposed to Cocaine.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4655.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Intrinsically photosensitive retinal ganglion cells (ipRGC’s) are considered to be a subset of retinal ganglion cells that are inherently photosensitive and provide a function in entrainment of the circadian clock. The purpose of this study is to assess ipRGC function among individuals with recent or concurrent cocaine exposure. Understanding that ipRGC action mediates circadian rhythm, it is posited that known sleep abnormalities found among cocaine users is related to abnormal ipRGC function.
Study design is a cross-sectional assessment of ipRGC function. Ten subjects (age range 31-69) with cocaine exposure without pre-existing ocular disease and congenital color vision deficiency were recruited. The test battery included assessment of cognitive function, depression and insomnia index, and Ocular Coherence Tomography (OCT) of the Nerve Fiber Layer to assess for confounding ganglion cell axonal thinning. After pupillary dilation, the consensual pupillary response was measured in the contralateral eye following 5 second stimulation in the dilated eye with 610nm and 470nm illumination at 8 and 30 µW energy levels. Abnormality of ipRGC function was noted by lack of the typical photopotentiation effect seen following 470 nm stimulation.
All but 1 subject demonstrated abnormal ipRGC function. OCT findings revealed a normal nerve in all recorded eyes. The insomnia index showed a spectrum ranging from none to severe insomnia.
The results indicate that pupillary response appears to be abnormal in patients with history of cocaine exposure as demonstrated by abnormal ipRGC function. Also demonstrated was an atypical pupil response to the 610nm light stimulus derived from photoreceptors, which suggests an alteration in cone sensitivity possibly related to cocaine exposure or withdrawal. Results thus far have not indicated a trend towards insomnia.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
This PDF is available to Subscribers Only