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Noemie Emelyn Kircher, Sylvain V Crippa, Catherine Martin, Aki K Kawasaki, Corinne Kostic; Immature Retina, Immature Pupil Light Response. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4138. doi: https://doi.org/.
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Besides light exposure, factors such as disease can influence the pupil size, in both transient and steady-state. This study examines the effect of gender and age on the pupil light response (PLR) in mice. To determine retinal activity and maturation, electroretinography was also recorded.
C57BL6 WT mice (n=27) were tested at 1, 2 and 4 months of age. Pupillometry was performed using red and blue light stimulations of different intensities (low, medium and high intensity, Kostic et al. 2016). Baseline pupil size, maximal contraction amplitude, post-illumination phase (ratio of contraction amplitude at 9.5s of stimuli onset to maximal contraction amplitude) and early pupillary dynamic (diameter changes during the first 2.5s after the stimuli onset) were analysed. Retinal activity was measured by ERG with a corneal electrode in response to single flashes of green light (from 10–4, to 30 cds/m2,Ganzfeld stimulator, Espion E3 apparatus). The amplitude and latency of a-wave and the b-wave were analyzed.
Age but not Gender influences the PLR and ERG recordings for all parameters examined.One month-old mice have smaller baseline pupil diameter than older animals tested (mean ±SEM pupil size 1.10 ±0.09,1.61 ±0.10, 1.91 mm ±0.09 respectively, p<0.001) and have larger maximal contraction amplitude in response to low and medium red stimuli compared with 2 month-old mice (e.g low red stimulus, mean ±SEM contraction amplitude 23.80 ±2.59% and 15.14 ±1.94% respectively, p<0.001). The early dynamic of the response differs only for low blue light stimulation with 1 month-old mice having a more rapid partial recovery than 2 months old animals. At medium red, medium blue and high blue stimulations, 1 month-old animals have a smaller ratio (e.g. for high blue stimulation, mean ratio ±SEM 0.65 ±0.12 and 0.92 ±0.04 respectively, p< 0.05). ERG recordings of 1 month-old mice reveal a higher a-wave and b-wave amplitude (p<0.001 and p<0.05 respectively) in scotopic condition compared to 2 month-old mice.
Gender has no effect on retinal function and pupil response in wild type mice, thus both males and females can be grouped into a single experimental design. However, age-related modifications for the PLR and for the retinal activity by ERG with age were detected. These results suggest that maturation of the retina takes place after 1 month of age and that the study of mouse adult retinal function should be performed from 2 months of age.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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