Chromatic Pupillometry Methods Establishment And Its Application On The Evaluation Of Visual Function

Pupil light reflex is a fundamental reflex in human being, which has important physiological significance. The reflex occurs to protect the retina from light damage when the illumination stimulus is on. Nowadays, the technique of pupillometry has been used in many fields, including ophthalmology, neuroscience, psychology, et al. Because of the advantage of objectivity, quantification, non-invasion and convenience of this technique, the studies concerning pupil light reflex increased in recent years. With the chromatic pupillometry and analysis system established by our team, we studied the effects of circadian rhythm, visual acuity, corneal refractive power and dark adaptation on pupil light reflex. And the characteristics of pupil light reflex under different stimulus parameters was also studied. Based on these studies, an evaluation method was established and verified in glaucoma and retinal pigmentosa patients.1. The effects of circadian rhythm, visual acuity and cornea refractive power on pupil light reflexPurpose:With measurement and analysis system of pupil light reflex developed byourselves, we aimed to study the effects of circadian rhythm, visual acuity, corneal refractive power on pupil light reflex.Methods: The pupil light reflex of 56 healthy volunteers was measured, which was compared under different test time, visual acuity, corneal refractive power. The parameters of initial pupil size, transient contraction amplitude, sustained contraction amplitude and maximum contraction velocity were used for evaluation.Results: The pupil light reflex did not differ each other under different test time. And the parameters of pupil light reflex did not correlate with visual acuity. While the corneal refractive power correlated with initial pupil size and maximum contraction velocity.Conclusions: We demonstrated that pupil light reflex was consistent under different test time and visual acuity, so it was not necessary to standardize them before the test. While the effect of corneal refractive power should be taken into consideration when testing or analyzing the pupil light reflex.2. Changes of pupil light reflex under different stimulus conditionsPurpose:To study the changes of pupil light reflex under different stimulus conditions and to establish appropriate stimulus protocol.Methods: The pupil light reflex of 17 healthy volunteers was evoked with 1) full-field blue and red stimulus of 100, 500, 1000 ms from 1 cd/m2 to 1000 cd/m2(13 intensities), 2) 45-degree blue and red stimulus of 1000 ms from 1 cd/m2 to 1000 cd/m2(13 intensities).Results: As the intensity of red stimulus increased, the transient contraction amplitude increased under 100 cd/m2 and then a plateau occurred, while the sustained contraction amplitude under red stimulus did not change much with the increasing of illumination intensity. Under the stimulus of blue stimulus, the transient contraction amplitude increased continuously as the intensity increasing and the largest transient contraction amplitude could be observed at the highest intensity stimulus. And the sustained contraction amplitude evoked by blue stimulus increased with increasing of stimulus intensity and reached a plateau at 400 cd/m2. Compared with the stimulus of short duration, the stimulus of 1000 ms could evoke stable pupillary contraction. Compared with stimulus of 45 o angle view and long duration, full-field stimulus with short duration evoked saturated contraction.Conclusions: The pupil light reflex under different stimulus condition changed with different characteristics. Based on the results, the protocol of full-filed, 1s duration and intensities of 100 cd/m2 could effectively evoked relatively saturated transient and sustained contraction.3. The effect of dark adaptation duration on pupil light reflex.Purpose: To establish an appropriate dark adaptation duration before the pupillometry test and study pupil light reflex driven by specific photoreceptors under different stimulus conditions.the stimulus condition that can evoke pupil light reflex driven by different photoreceptors.Methods: With the stimulus protocol of 1, 10, 100 cd/m2 red and blue stimulus, we evoked 15 volunteers’ pupil light reflex driven by different photoreceptors in the process of dark adaptation. The parameter of transient contraction amplitude and sustained contraction amplitude were analyzed. After 10 min 30 cd/m2 white illumination, the pupil light reflex was recorded during the adaptation at the time points of 1, 5, 10, 15, 20, 25, 30, 35, 40 min in the process of dark adaptation. And the dark adaptation curve was measured. The photoreceptive threshold at 20 min was used to evaluate the dark adaptation curve. Patients of glaucoma, macular hole and retinal pigmentosa were also tested with the same methods.Results: As the time of dark adaptation duration increased, pupillary transient contraction amplitude increased with different velocity and range under blue and red stimulus, which reached a plateau in the process of dark adaptation. But the sustained contraction driven by different photoreceptors differed a lot. The sustained contraction amplitude evoked by high-intensity blue stimulus increased with the dark adaptation time, which did not change much under red low-blue, median-blue stimulus. The inflection point for transient and sustained contraction was 15 and 20 min, respectively. Dark adaptation curve reach a threshold of 78.1±2.1 d B. Compared with the normal, the pupillary contraction of thepatients decreased by different extent and the threshold in dark adaptation increased. Based on the results, 100 cd/m2 red stimulus could evoke the pupil light reflex driven by cone cell; 1 cd/m2 blue stimulus could evoke the pupil light reflex driven by rod cell mainly; 100 cd/m2 blue stimulus could evoke the pupil light reflex driven by both of cone and ip RGC.Conclusions: As least 20 minutes was proposed before the test of pupil light reflex. The pupil light reflex driven by specific photoreceptors could be evoked by stimulus with different combination of wavelengths and intensities.4. The pupil light reflex in glaucoma and retinal pigmentosa patientsPurpose: To evaluate the effectivity of the stimulus protocol and appropriate dark adaptation duration for pupil light reflex established above in testing glaucoma and retinal pigmentosa patients.Method: The pupil light reflex was evoked in 24 glaucoma and 9 retinal pigmentosa patients with the stimulus of blue and red illumination of 1, 10, 100 cd/m2. The results was compared with the controls(Experiment 1). The transient contraction amplitude and sustained contraction amplitude were used to evaluate.Results: Compared with the normal, the transient and sustained contraction amplitude reduced in glaucoma patients, and the sustained contraction amplitude decreased a lot especially under the median and high-intensity blue stimulus. While in retinal pigmentosa patients, both of the transient and sustained contraction reduced obviously by similar extents under different stimulus conditions.Conclusions: The stimulus protocol could effectively detected the change in the pupil light reflex of glaucoma and retinal pigmentosa patients.Conclusions1. The corneal refractive power correlated with some parameters of pupil light reflex, which should be taken into consideration when the results was analyzed. Circadian rhythm and visual acuity did not affect the pupil light reflex, so it was not necessary to standardizethese factors before test.2. The duration, visual angle and intensity of the stimulus affected the pupil light reflex obviously. Stimulus with full-field and short duration could evoke saturated transient and sustained contraction.3. Before the test of pupil light reflex, at least 20-min dark adaptation was proposed to acquire stable pupil light reflex results. And the time effect of dark adaptation should be taken into consideration when pupil light reflex from different phases of dark adaptation was compared.4. With the stimulus protocol establish by the studies above, the pupil light reflex changed in different characteristics in glaucoma and retinal pigmentosa patients.