The intrinsically photosensitive retinal ganglion cell (ipRGC) mediated pupil response in young adult humans with refractive errors

Ranjay Chakraborty, Michael J. Collins , Henry Kricancic, Daniel Moderiano, Brett Davis, David Alonso-Caneiro, Fan Yi, Karthikeyan Baskaran

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    Abstract

    Abstract Purpose The intrinsically photosensitive retinal ganglion cells (ipRGCs) signal environmental light, with axons projected to the midbrain that control pupil size and circadian rhythms. Post-illumination pupil response (PIPR), a sustained pupil constriction after short-wavelength light stimulation, is an indirect measure of ipRGC activity. Here, we measured the PIPR in young adults with various refractive errors using a custom-made optical system. Methods PIPR was measured on myopic (−3.50 ± 1.82 D, n = 20) and non-myopic (+0.28 ± 0.23 D, n = 19) participants (mean age, 23.36 ± 3.06 years). The right eye was dilated and presented with long-wavelength (red, 625 nm, 3.68 × 1014 photons/cm2/s) and short-wavelength (blue, 470 nm, 3.24 × 1014 photons/cm2/s) 1 s and 5 s pulses of light, and the consensual response was measured in the left eye for 60 s following light offset. The 6 s and 30 s PIPR and early and late area under the curve (AUC) for 1 and 5 s stimuli were calculated. Results For most subjects, the 6 s and 30 s PIPR were significantly lower (p < 0.001), and the early and late AUC were significantly larger for 1 s blue light compared to red light (p < 0.001), suggesting a strong ipRGC response. The 5 s blue stimulation induced a slightly stronger melanopsin response, compared to 1 s stimulation with the same wavelength. However, none of the PIPR metrics were different between myopes and non-myopes for either stimulus duration (p > 0.05). Conclusions We confirm previous research that there is no effect of refractive error on the PIPR.
    Original languageEnglish
    Number of pages10
    JournalJournal of Optometry
    DOIs
    Publication statusAccepted/In press - 2 Jan 2021

    Keywords

    • Intrinsically photosensitive retinal ganglion cells
    • Pupil
    • Melanopsin
    • Refractive error
    • Myopia

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