Variability of pupil behaviour due to different retinal’s illumination levels

Purpose To get the knowledge about how can pupil size be manipulated, in an artificial way, by using optical filters, with different absorbances, in order to change the level of retinal’s illumination. This knowledge will allow the obtaining of an artificial myosis or mydriasis, with an optimal non-invasive technology, so that will be applied in several ways.Methods The transversal study included data from 56 eyes of 28 subjects. To measure the different pupil size was used a digital binocular infrared pupillometer, which simulated 3 different light’s conditions: high mesopic (4lux), low mesopic (0,4lux) and scotopic (0,04lux). The obtained pupil size measurements, without filter, were compared with the results after the insertion of the different optical filters used: 16 filters with different transmittances (from 82% to 5%).Results Only in high mesopic (4lux) condition, the results showed significant differences between the pupil size measurements without and with different transmittance optical filters. The mean variation was between 10% and 14% depending on the filter which was used.Conclusion The existence of a physiologically visual system limit for myosis in scotopic condition was confirmed, due to the lower amount of light in retina. Only in high mesopic condition, significant differences were obtained in the pupil size results with filter.