Pupil Center Shift Depending on Focal Retinal Stimulation?

¹Sandner D., ¹Genth U., ¹Pillunat L. E., ²Lutz P.,
¹Universitätsklinikum Carl Gustav Carus, Klinik und Poliklinik für Augenheilkunde (Dresden)
²SensoMotoric Instruments GmbH (Teltow)

Purpose: The constriction of the pupil during adaption is depending on the orientation of light illuminating the retina. This is to determine the shift of the center of the pupil and its shape during constriction depending on the orientation of the light projection.
Methods: The pupils of 14 persons were captured by infrared videography colinear to a fixation diode. The adaption for at least one minute was done at 16 lux, the retina was illuminated from temporal, superior, nasal and inferior at 8000 lux. Digital image processing using eye tracking algorithms was done to determine the size, the elliptical shape and the position of the pupil and the limbus. Using the position of the limbus as a reference leads to the amount of pupil center shift.
Results: Average pupil size adapted to dark was 4.3±1.1mm (SD), the eccentricity was 0.037. Under light conditions the average was 3.0±0,52mm, the eccentricity was 0.04. The mean shift of the pupil was 0.18±0.14mm (SD) for the right and 0.22±0.13mm (SD) for the left eye, the mean direction of the center shift was towards nasal and was not depending on the orientation of projected light.
Conclusions: The center of the pupil is not independent from the pupil size, under different light conditions the pupil center is shifting. It is also considerable that pharmacologically dilated pupils showed an increasing center shift. Although eye trackers used in refractive surgery are fast enough to determine the pupil center even under mydriatic conditions, it should be considered that the detected center of the cornea may vary during PRK or Lasik.

Copyright © Deutsche Ophthalmologische Gesellschaft, 2002. All rights reserved.

Last updated: 

Webdesign: SPALLEK.COM