![]() The subject was requested to stay in position at the device. After each illuminance level, the recording was paused for 5–10 seconds to allow the pupil diameter to return to baseline and to provide a short break for the participant. At each continuous level of illumination, 90 images were acquired with two focus-free infrared cameras (880 nm), 30 images per second over a measurement period of 3 seconds. The patient’s eyes were measured at five illumination levels, starting at 0 lux. The participants saw a white uniform LED (light-emitting diode) field (Cree XP-G2 continuous distribution with peaks at approximately 440 and 550 nm, colour temperature of ~6500 K) with adjustable brightness, which could be switched off for scotopic conditions. The subjects were requested to look straight ahead and keep their eyes open for the whole measurement period. By using light-tight rubber eyecups, the PupilX pupillometer allows for measurements under scotopic conditions without the need to completely darken the examination room. This was monitored by the same investigator. Furthermore, all patients underwent a 2-minute retinal adaptation phase in the same room under low mesopic conditions (darkened room where the only light was from the device). ![]() No subject was exposed to bright light directly before the measurement. The protocol order proceeded from the dimmest to the brightest condition. The aim of this study was to evaluate the pupil size of healthy subjects at different illumination levels in order to establish normative data for pupil size measured with PupilX.Ī participant’s pupil diameter was measured at five successive illumination levels with 0, 0.5, 4, 32, and 250 lux. PupilX provided the most accurate bilateral measurements compared with ProCyon and unilateral measurements compared with Colvard. compared the pupil size of healthy subjects measured with PupilX, ProCyon (Proscience Instruments, London, UK), and Colvard (Oasis Medical Inc., San Dimas, CA, USA) and demonstrated a disparity in the precision of the different devices. A deflection mechanism via mirrors prevents direct illumination, allowing for measurements of pupil size under uniform light conditions. 2 The device works with a telecentric optical system with two focus-free infrared cameras (880 nm), so no adjustment of the oculars or pupil distance is required. 4Ī recently developed pupillometer PupilX (Albomed GmbH, Schwarzenbruck, Germany) makes it possible to measure bilateral pupil sizes simultaneously under constant and adjustable illumination levels, facilitating comparable measurements under scotopic, mesopic, and photopic conditions. Moreover, even differences in iris colour can complicate the identification of iris borders. 10, 11 Due to spontaneous pupillary oscillations, it is difficult to measure pupil size during free gaze. 7– 9 The complexity of comparable and reliable data on pupil size is still problematic, and factors such as illumination, accommodation, and attention might influence the accuracy of measurement. 5, 6 Only a few studies under photopic illumination conditions were conducted. The majority of previous pupil size studies were executed under scotopic conditions in healthy eyes. 2– 4 Previously, pupillometric analyses were performed with variable devices and under variable test conditions. 1 In clinical routine, the precise and easy measurement of pupil size is important for the planning and outcome of refractive surgery and neuro-ophthalmological investigations. Pupil size determines retinal illuminance and the quality of the retinal image via optimizing diffraction, ocular aberrations, and depth of focus. This study provides additional information to the current knowledge concerning age- and light-related pupil size and anisocoria as a baseline for future patient studies. Anisocoria was higher under scotopic and mesopic conditions. Furthermore, it was found that anisocoria increased by 0.03 mm per life decade for all illumination levels ( R 2 = 0.43). On average, pupil diameter decreased with increasing light intensities for both eyes, with a mean pupil diameter of 5.39 ± 1.04 mm at 0 lux, 5.20 ± 1.00 mm at 0.5 lux, 4.70 ± 0.97 mm at 4 lux, 3.74 ± 0.78 mm at 32 lux, and 2.84 ± 0.50 mm at 250 lux illumination. This cross-sectional study analysed 490 eyes of 245 subjects (mean age: 51.9 ± 18.3 years, range: 6–87 years). The absolute linear camera resolution was approximately 20 pixels per mm. Ninety images were executed during a measurement period of 3 seconds. Measurements were performed by the same investigator. The pupil size of healthy study participants was measured with an infrared-video PupilX pupillometer (MEye Tech GmbH, Alsdorf, Germany) at five different illumination levels (0, 0.5, 4, 32, and 250 lux). The aim of this study was to evaluate the pupil size of normal subjects at different illumination levels with a novel pupillometer.
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