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Table 1 Pupil response metrics in four study populations using the Portable Field Dark Adaptometer (2010–2013)

From: A novel device for assessing dark adaptation in field settings

Country, Assessment Year Bangladesh, 2010 Kenya, 2010 Zambia, 2012 Peru, 2013
Study Population Pregnant women School-aged children Preschool-aged children Adults
 n 242 184 305 91
 Male, n (%) 0 (100.0) 79 (43.0) 148 (48.5) 44 (48.4)
 Mean age ± SD 23.4 ± 6.1 9.2 ± 1.9 5.7 ± 1.3 55.1 ± 10.9
Mean relative change ± SD in pupil diameter (%)1    
 All stimuli: -2.9 to 0.1 log cd/m2 −19.8 ± 5.0 −15.5 ± 5.8 −17.0 ± 6.8 −22.7 ± 8.0
 Low intensity: −2.9 to −1.3 log cd/m2 −14.5 ± 5.3 −9.4 ± 5.1 −9.2 ± 5.9 −16.3 ± 7.6
 High intensity: −0.9 to 0.1 log cd/m2 −26.2 ± 5.4 −23.1 ± 7.5 −26.7 ± 8.3 −30.5 ± 8.8
Mean response time (s) 2     
 All stimuli: −2.9 to 0.1 log cd/m2 1.27 ± 0.31 1.02 ± 0.16 1.11 ± 0.21 1.13 ± 0.18
 Low intensity: −2.9 to −1.3 log cd/m2 1.21 ± 0.29 0.90 ± 0.19 1.00 ± 0.21 1.07 ± 0.22
 High intensity: −0.9 to 0.1 log cd/m2 1.35 ± 0.44 1.17 ± 0.17 1.24 ± 0.25 1.20 ± 0.22
Mean +/- SD pupillary threshold (log cd/m2) −1.87 ± 0.75 −1.20 ± 0.83 −1.34 ± 0.70 −1.91 ± 0.81
Distribution of pupillary thresholds (%)3     
 Good: −2.9 to −2.1 cd/m2 49.2 23.4 20.7 59.3
 Adequate: −1.7 to −0.9 cd/m2 42.1 42.9 55.3 29.7
 Impaired: −0.5 to 0.1 cd/m2 8.7 33.7 24.0 11.0
  1. 1Pre- to post-stimulus change pupil diameter (in pixels), expressed as proportion of pre-stimulus diameter; figures are mean +/- SD; lower values reflect a greater response/better dark adaptation
  2. 2Absolute value of the difference in video frame number from pre- to post-stimulus, divided by 30 frames/s; higher values reflect a faster response/better dark adaptation
  3. 3Pupillary threshold defined as first stimulus at which pupil diameter decreased by 20 % or more; abnormal as defined by Congdon et al. [8], i.e., pupillary threshold > = −0.5 log cd/m2