Interexaminer and Intraexaminer Reliability of Pupil Diameter Measurement using the Colvard Pupillometer

Abstract

Abstract: : Purpose: To evaluate the interexaminer and intraexaminer agreement of pupil size diameter measurements determined using the Colvard pupillometer. Methods: The right eyes of 69 patients were examined (T1) using the Colvard pupillometer under low light and dark conditions (mesopic and scotopic) by two examiners, and repeated 1 hour (T2) and 24 hours (T3) later. The limits of agreement (mean difference between measurements ± 2 standard deviations) were calculated for measurements between examiners (interexaminer agreement) and between different time points measured by the same examiner (intraexaminer agreement). Z-values were also calculated to measure the associated probability that a given measurement difference was less than a specified interval distance (within 0.5 mm). Results: At T1, there was a 98.4% and 93.4% chance of two different examiners producing readings within 0.5mm under mesopic and scotopic conditions, respectively. There was a 13.7% chance and a 14.8% chance of finding a pupil difference greater than 0.50 mm over one hour under mesopic and scotopic conditions respectively. For mesopic and scotopic measurements taken 24 hours apart, there was respectively a 37.7 % chance and a 40.7% chance of finding a difference greater than 0.50 mm by the same examiner. Conclusions: This study showed high interexaminer agreement under scotopic conditions, with 98.4% agreement within 0.50 mm between two examiners, but substantial variability in a given patient's pupil diameter measurements over 24 hours. These results suggest that serial office measurements may be necessary to assess risk associated with pupil size.

Keywords: refractive surgery: LASIK • clinical (human) or epidemiologic studies: sys • pupil