Reproducibility and normal values of static pupil diameters



To provide additional information on normal values of static pupil diameter measurements for binocular infrared pupillometry with PupilX, a commercial pupillometer, and assess the reproducibility of this device’s measurements.


The pupil diameters from 91 study participants with normal eyes with an average age of 39.7 years (SD 16.4 years) were measured with PupilX under scotopic (0 lx), mesopic (1 lx), and photopic (16 lx) illumination. To assess the repeatability of the device, each measurement was repeated 5 times.


The mean pupil diameters were 6.5 mm (SD 1.3 mm), 5.5 mm (SD 1.2 mm), and 4.03 mm (SD 0.9 mm) under scotopic, mesopic, and photopic illumination. Left and right eyes showed no difference in mean pupil diameters. The mean unsigned anisocoria was 0.26 mm (SD 0.32 mm) under scotopic, 0.26 mm (SD 0.27 mm) under mesopic, and 0.19 mm (SD 0.19 mm) under photopic illumination. The decrease in pupil diameter with age was largest for scotopic (≈0.057 mm/y) and smallest for photopic illumination (≈0.025 mm/y). The repeatability of the pupillometer was better than 0.2 mm.


This study provides reference values for age- and light-related pupil diameters measured with the PupilX digital pupillometer in normal subjects.

Post author correction


Article Subject: Lens/Cataract



Simon Schröder, Ekaterina Chashchina, Edgar Janunts, Alan Cayless, Achim Langenbucher

Article History


Financial support: Funding provided through a scholarship (A/11/86522) granted to the author’s study (E.C.) from the German Academic Exchange Service (DAAD) and the Dr. Rolf M. Schwiete Foundation (E.J.).
Conflict of interest: None of the authors has conflict of interest with this submission.

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  • Department of Experimental Ophthalmology, Saarland University, Homburg - Germany
  • Department of Physical Sciences, Open University Edinburgh, Milton Keynes - UK

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