Abstract
Continuous and intermittent stimuli with green light affect the pupillary light response (PLR) differently. Since the majority of pupillometric studies use blue and red lights, we investigated the effect of continuous and intermittent stimulations on the PLR using red and blue lights. Seventeen healthy subjects underwent continuous- and intermittent light stimuli, using red (643 nm) and blue light (463 nm). To avoid the influence of pupil size on the amount of light entering the eye, the procedures were repeated with the stimulus-eye in dilated condition. The maximal pupillary constriction and the early redilation phase of post-illumination pupillary response (PIPREarly) represented the mixed response of melanopsin and rod-cone photoreceptors. The late redilation phase of PIPR (PIPRLate) was the marker of melanopsin-containing retinal ganglion cells. Intermittent stimuli with blue light elicited significantly larger maximal contraction during dilated condition (P = 0.001), and larger sustained pupillary contraction under dilated as well as undilated condition (P < 0.001) compared to continuous light exposure. Except the PIPREarly during undilated condition, none of the PIPR metrics were significantly different between intermittent and continuous blue light stimuli. Intermittent red light stimuli elicited also a more sustained pupillary contraction regardless of mydriatic instillation (P ≤ 0.02). In addition, intermittent red light exposure resulted in a slightly larger PIPREarly under undilated condition (P = 0.02) and a slightly larger PIPRLate under dilated condition (P = 0.049). Except the PIPRLate to continuous red light stimulus, all PIPR parameters were larger when the light was presented after induction of unilateral mydriasis. PLR parameters during and after light exposures depend on both the light stimulation mode and the entrance pupillary size.
Highlights
Except the PIPRLate to continuous red light stimulus, all post-illumination pupillary response (PIPR) parameters were larger when the light was presented after induction of unilateral mydriasis
Since the discovery of the melanopsin-containing intrinsic photosensitive retinal ganglion cells and their involvement in the pupillary light response (PLR), a common method for in vivo quantification of the ipRGCs response has been the measurement of PLR to different narrowband light stimuli
Recent studies have shown that PIPR has two phases: an early redilation phase, owing to mixed signals from ipRGCs and rod/cone, and a late redilation phase, which is solely maintained by the melanopsin contribution [10,11,12]
Summary
Since the discovery of the melanopsin-containing intrinsic photosensitive retinal ganglion cells (ipRGCs) and their involvement in the pupillary light response (PLR), a common method for in vivo quantification of the ipRGCs response has been the measurement of PLR to different narrowband light stimuli. This method is popularly known as chromatic pupillometry. Based on the maximum spectral sensitivity and light intensity threshold of the different photoreceptors, various chromatic pupillometry protocols, aiming to differentiate the PLR driven by rods, cones, and melanopsin, have emerged [1,2,3]. Recent studies have shown that PIPR has two phases: an early redilation phase, owing to mixed signals from ipRGCs and rod/cone, and a late redilation phase, which is solely maintained by the melanopsin contribution [10,11,12]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
