Abstract
Purpose: :
To evaluate the agreement and test-retest reliability of pupil size measurements under scotopic conditions with two digital infrared pupillometers.
Methods: :
In 54 eyes of 27 healthy volunteers (mean age 44 years ± 18 (SD)) pupil size was measured with two digital infrared pupillometers (Procyon P2000 SA and Neuroptics VIP-200) at 0.04 lux scotopic illumination. Prior to measurement a standardized dark-adaptation protocol was used. Measurements were taken twice with each instrument on the same day. Results were analyzed with the Bland-Altman method, a paired t-test was used to test for a statistically significant difference in measurements.
Results: :
A scotopic pupil diameter of 5.9 mm ± 0.83 SD and 6.2 mm ± 0.71 SD respectively was measured with the Procyon and the Neuroptics device. The mean difference of measurements taken with the two pupillometers was 0.3 mm ± 0.41 SD. The difference in measurements was statistically significant (p<0,001). Repeated measurements of the Neuroptics pupillometer showed a higher test-retest agreement of consecutive measurements as compared to the Procyon device resulting in a lower standard deviation of differences of consecutive measurements (Neuroptics 0.17 mm, Procyon 0.43 mm).
Conclusions: :
Under scotopic illumination conditions using a standardized dark adaptation protocol pupil diameter assessed with the Neuroptics device was significantly larger as compared to the Procyon pupillometer. Repeated measurements with the Neuroptics pupillometer showed smaller spread and were better reproduced.
Keywords: pupil • refractive surgery • optical properties