A pupillary light reflex (PLR) model was proposed in this paper by considering the iris muscle mechanical properties and modulation inputs from both parasympathetic and sympathetic systems. The model can describe very well the experimental PLR responses induced by a short light flash of various intensities. In addition, an inverse method was developed to fit numerically this model to experimental PLR data. The model was tested in experimental human PLR data to extract separately the parasympathetic and sympathetic modulations during PLR. The results indicated a higher parasympathetic and a lower sympathetic activity in females than in males, which was consistent with previous findings in cardiovascular studies. This new model may help improve our understanding of the PLR process and could be applied to analyze autonomic nervous interaction during pupillary responses.

purpose. Contraction anisocoria describes a phenomenon in which the pupil of a directly illuminated eye constricts more than the pupil of the consensual (not illuminated) eye. The purpose of this study was to investigate the lateralization of contraction anisocoria in young female and male subjects. methods. Infrared binocular pupillography was used to measure pupillary light reflex (PLR) in 44 healthy children (23 girls, 21 boys) from 6 to 16 years of age. Measurements were conducted in both light-adapted and dark-adapted conditions with different stimulus intensities. Relative constriction amplitude was obtained by dividing the maximal pupil area change by the initial static pupil area. Contraction anisocoria was calculated by subtracting relative constriction amplitude in the consensual eye from that of the direct eye. Values of contraction anisocoria obtained by stimulating a subject’s right or left eye were compared to determine any potential lateralization. results. It was found that stimulating the right eye led to larger contraction anisocoria than stimulating the left eye. Such right-side lateralization of contraction anisocoria is much greater in males than in females. In addition, the effects of sex were related to the ambient light level and stimulus intensity. conclusions. These results provide evidence that contraction anisocoria is more laterally asymmetric in males than in females.

Computerized binocular infrared pupillography was used to measure the transient pupillary light reflex (PLR) in both children with autism spectrum disorders (ASDs) and children with typical development. We found that participants with ASDs showed significantly longer PLR latency, smaller constriction amplitude and lower constriction velocity than children with typical development. The PLR latency alone can be used to discriminate the ASD group from the control group with a cross-validated success rate of 89.6%. By adding the constriction amplitude, the percentage of correct classification can be further improved to 92.5%. In addition, the right-lateralization of contraction anisocoria that was observed in participants with typical development was not observed in those with ASDs. Further studies are necessary to understand the origin and implications of these observations. It is anticipated that as potential biomarkers, these pupillary light reflex measurements will advance our understanding of neurodevelopmental differences in the autism brain.

We investigated the gender effects on transient pupillary light reflex (PLR) in healthy young adults between 18 and 22 years old. Both dark-adapted and light-adapted PLRs were measured using green and red stimuli of different intensities. The results indicate that females had significantly larger relative constriction amplitudes than males in a dark-adapted condition. This gender effect depends on the stimulus intensities. The relative constriction amplitude in female subjects increased faster than it did in the males with the stimulus intensity. We did not observe any significant gender differences in the other PLR parameters, including latency, constriction speed, and recovery speed.

We used optical imaging of intrinsic signals to study visual cortex responses in three mouse strains: wild-type (C57BL/6J), a strain with only rod function (cpfl1), and a strain with only cone function (rho−/−). A stationary flicker light stimulus with intensity ranging from 108.6 to 1015.5 photons/cm2/s was used. We found that the intrinsic signal patterns exhibited stimulus intensity-dependent changes. At a given stimulus intensity, the patterns of intrinsic signals were clearly different in the three strains. These results suggest that the lack of normal functions of certain photoreceptors induces significant reorganization in the visual neural systems in mice.