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Alireza Akhlagh Moayed, Vivian Choh, Sepideh Hariri, Chenyi Liu, Alexander Wong, Kostadinka Bizheva; Stimulus-Specific Pupil Dynamics Measured in Birds (Gallus gallus domesticus) In Vivo with Ultrahigh Resolution Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2012;53(11):6863-6869. doi: 10.1167/iovs.12-10291.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate the ability of high speed, ultrahigh-resolution optical coherence tomography (UHR-OCT) to measure and characterize in vivo visual stimulus-specific pupil dynamics in birds.
Ten two-week old White Leghorn ( Gallus gallus domesticus ) chickens were imaged in this study. The chickens were dark-adapted for 1 hour and anesthetized with 2% isoflurane prior to the imaging procedure. Blue, green, and red single flash visual stimuli of 7 ms duration were used to evoke pupillary responses. UHR-OCT cross-sectional images of the pupil were acquired prior, during, and for several seconds after the visual stimuli onset. Images were processed with a novel custom automatic algorithm, designed to determine the pupil diameter changes over time.
Results from this study show that the pupillary constriction begins with the onset of the visual stimuli; however, maximum pupil constriction occurs ∼150 ms later. No statistically significant variation in the timing of the maximum pupillary constriction was observed for stimuli of different colors. However, significant variation was observed in the maximum pupil constriction amplitudes, between red-green and red-blue stimuli, but not between blue-green stimuli. Furthermore, the magnitude of the maximum pupil constriction decreased monotonically with time under isoflurane anesthesia.
We demonstrated, for the first time, measurements of visually evoked pupillary dynamics in animals using high speed UHR-OCT. The results suggest dependence of the pupillary dynamics on the color of the visual stimulus, and adverse effects of isoflurane anesthesia on the visually evoked pupillary responses in chickens.
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