Agreement and repeatability of pupillometry using videokeratography and infrared devices

Purpose: To evaluate the accuracy and repeatability of the pupil-measuring modules of several corneal topography devices. Setting: Department of Ophthalmology, Saint Louis University Eye Institute, St. Louis, Missouri, USA. Methods: In 14 eyes of 7 healthy myopic patients, pupillometry was performe d with 3 corneal topography devices and with an infrared pupillometer under luminance-matched conditions for the Placido projection of the topography devices. Pupils were also measured under a mesopic condition. Outcomes were pupil diameters, limits of agreement, and coefficient of repeatability of the topography devices. Results: Mean pupil diameter measurements with the Technomed C-Scan, Humphr ey Masterview, Alcon EyeMap, and under a mesopic condition were 3.35 mm, 2. 96 mm, 2.34 mm, and 5.94 mm, respectively. All pupil diameter measurements differed significantly from one another except those by the Masterview and C-Scan devices. The mean difference between the C-Scan and luminance-matche d infrared measurements was 0.74 mm and between the Masterview and luminanc e-matched infrared measurements, 0.27 mm. The limits of agreement +/-2 stan dard deviations was 4.12 mm and 1.56 mm for the C-Scan and Masterview devic es, respectively. Coefficients of repeatability were 0.56 mm, 0.46 mm, and 0.44 mm for the C-Scan, Masterview, and EyeMap devices, respectively. Conclusions: Although topography pupillometry was repeatable, it underestim ated the largest natural pupil diameter because of the luminance of the Pla cido rings. The difference in limits of agreement between the C-Scan and Ma sterview devices may be explained by pupil physiology and the static nature of videokeratoscopy. These results have implications when topography pupil lometry is used to assess pupil diameters prior to refractive surgery. We d o not recommend using pupil diameters measured by topography to preoperativ ely determine halo-related safety. J Cataract Refract Surg 2000; 26:35-40 ( C) 2000 ASCRS and ESCRS.