Table 2.

Pupil metrics used to quantify photoreceptor contributions to the post-illumination pupil response. Metrics include baseline pupil diameter (%), peak constriction (% of baseline), 6 s and 30 s post-illumination pupil response (PIPR, % of baseline) and early and late area under the curve (AUC, unitless).

Metric	Definition	Unit	Expected change	Photoreceptor contribution
Baseline pupil diameter	10 s pre-stimulus period before long-and-short-wavelength stimulation	Percent (%)
Peak constriction	Maximum pupil constriction	% of the average baseline pupil diameter	Smaller value indicates greater constriction	Combination of rod/cone and inner retinal activity
6 s PIPR	Mean pupil diameter 6–7 s after stimulus offset	% of the average baseline pupil diameter	Smaller value indicates greater ipRGC activity	ipRGC activity
30 s PIPR	Mean pupil diameter 30–31 s after stimulus offset	% of the average baseline pupil diameter	Smaller value indicates greater ipRGC activity	ipRGC activity
Early AUC	Log of trapezoidal approximation of the integral of 100% baseline minus the interpolated % pupil diameter, 0–10 s after stimulus offset	Unitless	Larger value indicates greater ipRGC activity	ipRGC activity
Late AUC	Log of trapezoidal approximation of the integral of 100% baseline minus the interpolated % pupil diameter, 10–30 s after stimulus offset	Unitless	Larger value indicates greater ipRGC activity	ipRGC activity