|Pupil responses to blue light and red light of equiluminant intensity (300 cd/m2) and their correlations to age|
|Test condition||Correlation to age|
|Para-Meter||Light color||Light, intensity cd/m2||Mean||95% CI||b||R2||p value|
|LIGHT ON PARAMETERS|
|Maximal CA, %||red||300||43.5||41.1–46.0||–0.008||0.06||0.95|
|Sustained CA, %||red||300||37.2||34.5–40.0||0.18||0.09||0.16|
|LIGHT OFF PARAMETERS|
|Early post-stim. AUC||red||300||1.6||1.4–1.7||–0.0002||0.04||0.97|
|Late post-stim. AUC||red||300||0.7||0.6–0.9||–0.01||0.008||0.15|
Pupil response parameters are given as mean with 95% confidence interval.
The correlation between pupil responses and age was calculated by a multiple linear regression with adjustment for baseline pupil size and gender. Results are given as: b, the slope of the regression (response change per year), R2, the correlation coefficient, i.e., the fraction of variance explained by the regression model and the p-value.
Contraction amplitudes (CA): Maximal CA is difference between baseline pupil size (BS) and the normalized pupil size (NPS) at maximal contraction to light. Sustained CA is the difference between BS and NPS during the last second of light stimulation.
Areas under the curve (AUC): Early poststimulus AUC is the summed response amplitudes within 0–10 s after light termination. Late poststimulus AUC is the summed response within 10–30 s after light termination.
Light stimulus luminance of 300 cd/m2 red (660 nm) or 300 cd/m2 blue (470 nm) light corresponded to 14.9 and 14.8 log photons/cm2/s, respectively.
* Level of significance p < 0.05. CI, confidence interval; b, slope of the regression; R2, correlation coefficient; CA, contraction amplitude; AUC, area under the curve (the summed pupil response amplitudes within the given time window.
Herbst et al. BMC Ophthalmology 2012 12:4 doi:10.1186/1471-2415-12-4