Table 1 Comparisons of experimental parameters in studies on PLR or PIPR in older adults

Daneaut et al. [82]. 2012

16 young adults (22.8 ± 4 years old), and 14 older adults (61 ± 4.4 years old) including subjects with level 2, 3 or 4 in LOCS III [86]

NOT dilated

Steady-state PLR

(Averaged pupil size during 39 s of light exposure)

Dark adaptation (0 lx): 15 min before first stimulus; 2 min between stimuli

Wavelength: Blue light (480 nm) and green light (550 nm)

Intensity: Low: 7 × 10¹² photons/cm²/s; Medium: 3 × 10¹³ photons/cm²/s; High: 10¹⁴ photons/cm²/s irradiance

Duration: 45 s

There was no difference between age groups

Kankipati et al. [78]. 2010

37 normal subjects between ages of 19 and 80 years

Dilated

PIPR

(Using average pupil size over a period of 30 s, starting 10 s after light offset)

Dark adaptation: None mentioned

*Interval between red and blue stimuli was 5 min

Wavelength: Blue light (470 nm) and red light (623 nm)

Intensity: 13 log quanta/cm²/s (estimated retinal irradiance)

Duration: 10 s

No significant correlation was found between PIPR and age

Adhikari et al. [84]. 2015

59 healthy subjects between ages of 21 and 70 years. All participants had a lens grading of ≤ 2 in LOCS III

Dilated and NOT dilated

PLR (Transient PLR, peak pupil constriction) and PIPR (6 s PIPR, Plateau PIPR, AUC early, AUC late)

Dark adaptation (< 6 lx): 10 min

Wavelength: Blue light (448 nm) and red light (604 nm)

Intensity: Blue: 14.5 log quanta/cm²/s; Red: 14.4 log quanta/cm²/s (corneal irradiance)

Duration: 1 or 10 s

There is no effect of age

Herbst et al. [83]. 2012

44 healthy subjects aged between 26 and 68 years

NOT dilated

PLR (Maximal pupil contraction) and PIPR (Sustained pupil contraction, AUC early, AUC late)

Dark adaptation (0 cd/m²): 1 min after 4 min mesopic lighting condition (0.74 cd/m²)

Wavelength: Blue light (470 nm) and red light (660 nm)

Intensity: 3, 30, 100 and 300 cd/m² (corresponding irradiance when intensity is 300 cd/m²: Blue 14.8 log photons/cm²/s; Red 14.9 log photons/cm²/s)

Duration: 20 s

Sustained pupil contraction and AUC early correlated positively with age

Rukmini et al. [85]

2017

60 young normal adults aged 21—30 years and 54 older adults aged ≥ 50 years including mild cataracts and severe cataracts

NOT dilated

Dose–response curve of PLR

Dark adaptation: 1 min

Wavelength: Blue light (469 nm) and red light (631 nm)

Intensity: Gradually increase over 2 min from 6.8–13.8 log photons/cm²/s

Duration: 2 min

Irrespective of wavelength, pupillary responses were reduced in older individuals and further attenuated by severe, but not mild cataract