Correlation of infrared pupillometers and CCD-camera imaging from aberrometry and videokeratography for determining scotopic pupil size

Abstract

Purpose: To compare 2 infrared pupillometers with a videokeratographer and 2 aberrometers for the determination of scotopic pupil size. Setting: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. Methods: The pupil diameter was measured in 100 eyes of 51 patients after 2 minutes of dark adaptation using the following devices: digital infrared pupillometer (Procyon Instruments Ltd.), handheld infrared pupillometer (Colvard) (Oasis Medical), Zywave® aberrometer (Bausch & Lomb), Wasca aberrometer (Asclepion-Meditec-Zeiss), and Orbscan® II topography system (Bausch & Lomb Surgical). Measurements taken with the Procyon pupillometer were considered reference values for comparison with the other devices. Statistical evaluation was performed using the Bland-Altmann method for comparison of measurement techniques. Results: The mean pupil size was 6.10 mm ± 0.86 (SD) with the Procyon pupil- lometer, 5.68 ± 1.07 mm with the Colvard pupillometer, 5.91 ± 1.01 mm with the Zywave aberrometer with the fixating target turned off, 5.09 ± 1.14 mm with the Zywave aberrometer with the fixating target turned on, 5.59 ± 0.99 mm with the Wasca aberrometer, and 3.75 ± 0.67 mm with the Orbscan topographer. The limits of agreement were smallest for measurements between Procyon and Colvard and largest for measurements between Procyon and Orbscan. The sign test revealed statistically significant differences for all devices compared with the Procyon pupillometer ( P<.001 in all cases) except the Zywave aberrometer with the fixating target turned off ( P = .13). Conclusions: The Zywave wavefront sensor with the fixating target turned off using the study settings and light conditions provided measurements of scotopic pupil diameter that were closest to the reference values (Procyon). With the other devices (Colvard pupillometer, Zywave aberrometer with the fixating target switched on, Wasca aberrometer, and Orbscan topographer), the difference was statistically significant.