Scotopic measurement of normal pupils: Colvard versus Video Vision Analyzer infrared pupillometer

Abstract

Purpose To prospectively measure the scotopic pupil diameter in a normal population and to compare 2 infrared pupillometers for these measurements. Setting Johann Wolfgang Goethe-University, Department of Ophthalmology, Frankfurt am Main, Germany. Methods The Colvard infrared pupillometer was compared to the Video Vision Analyzer (VIVA) infrared pupillometer under scotopic light conditions in 33 participants (aged 19 to 55 years). Reliability was assessed by 2 independent examiners (E1, E2). Statistical analysis was performed using a comparison method by Bland and Altman. Results Mean pupil diameter was 6.16 mm ± 1.20 (SD) (range 3.20 to 9.00 mm) with all measurements taken under scotopic illumination. The mean scotopic pupil diameter was 6.08 ± 1.16 mm (range 3.2 to 8.4 mm) with the Colvard pupillometer and 6.24 ± 1.28 mm (3.5 to 9.0 mm) with the VIVA pupillometer. The mean differences between the Colvard and VIVA were −0.27 mm (E1) and −0.05 mm (E2). Limits of agreement ranged from 1.4 (Colvard) to 2.4 (VIVA). The coefficients of repeatability ranged from 0.7 (Colvard) to 1.1 (VIVA). Conclusions A mean scotopic pupil diameter of 6.15 mm with a maximal pupil size of 9.00 mm can be expected in a normal population; this should be considered in refractive corneal and refractive lens surgery. Measurements with the Colvard pupillometer were more reliable and precise than those with the VIVA pupillometer.