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Individual Differences in the Post-Illumination Pupil Response to Blue Light: Assessment without Mydriatics

View Article: PubMed Central - PubMed

ABSTRACT

Melanopsin-containing retinal ganglion cells play an important role in the non-image forming effects of light, through their direct projections on brain circuits involved in circadian rhythms, mood and alertness. Individual differences in the functionality of the melanopsin-signaling circuitry can be reliably quantified using the maximum post-illumination pupil response (PIPR) after blue light. Previous protocols for acquiring PIPR relied on the use of mydriatics to dilate the light-exposed eye. However, pharmacological pupil dilation is uncomfortable for the participants and requires ophthalmological expertise. Hence, we here investigated whether an individual’s maximum PIPR can be validly obtained in a protocol that does not use mydriatics but rather increases the intensity of the light stimulus. In 18 participants (5 males, mean age ± SD: 34.6 ± 13.6 years) we evaluated the PIPR after exposure to intensified blue light (550 µW/cm2) provided to an undilated dynamic pupil. The test-retest reliability of the primary PIPR outcome parameter was very high, both between day-to-day assessments (Intraclass Correlation Coefficient (ICC) = 0.85), as well as between winter and summer assessments (ICC = 0.83). Compared to the PIPR obtained with the use of mydriatics and 160 µW/cm2 blue light exposure, the method with intensified light without mydriatics showed almost zero bias according to Bland-Altman plots and had moderate to strong reliability (ICC = 0.67). In conclusion, for PIPR assessments, increasing the light intensity is a feasible and reliable alternative to pupil dilation to relieve the participant’s burden and to allow for performance outside the ophthalmological clinic.

No MeSH data available.


Bland-Altman plots for PIPR-mm (left) and PIPR-% (right) between the first summer sessions and winter assessments of the protocol with intensified blue light (550 µW/cm2) with a natural pupil (550My−). Differences between the two measurements (i.e., summer minus winter) are plotted against the mean of the two measurements. The dotted line represents the bias, i.e., the mean difference between all measurements of the summer and the winter.
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biology-05-00034-f004: Bland-Altman plots for PIPR-mm (left) and PIPR-% (right) between the first summer sessions and winter assessments of the protocol with intensified blue light (550 µW/cm2) with a natural pupil (550My−). Differences between the two measurements (i.e., summer minus winter) are plotted against the mean of the two measurements. The dotted line represents the bias, i.e., the mean difference between all measurements of the summer and the winter.

Mentions: The Bland-Altman plots also indicated almost zero bias between 550My− winter and 550My− summer measurements for PIPR-mm and PIPR-% (Figure 4), indicating high agreement. Again, the ICC values indicated a very high reliability for the PIPR outcome parameters (PIPR-mm: ICC = 0.83; PIPR-%: ICC = 0.80) (Table 5).


Individual Differences in the Post-Illumination Pupil Response to Blue Light: Assessment without Mydriatics
Bland-Altman plots for PIPR-mm (left) and PIPR-% (right) between the first summer sessions and winter assessments of the protocol with intensified blue light (550 µW/cm2) with a natural pupil (550My−). Differences between the two measurements (i.e., summer minus winter) are plotted against the mean of the two measurements. The dotted line represents the bias, i.e., the mean difference between all measurements of the summer and the winter.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037353&req=5

biology-05-00034-f004: Bland-Altman plots for PIPR-mm (left) and PIPR-% (right) between the first summer sessions and winter assessments of the protocol with intensified blue light (550 µW/cm2) with a natural pupil (550My−). Differences between the two measurements (i.e., summer minus winter) are plotted against the mean of the two measurements. The dotted line represents the bias, i.e., the mean difference between all measurements of the summer and the winter.
Mentions: The Bland-Altman plots also indicated almost zero bias between 550My− winter and 550My− summer measurements for PIPR-mm and PIPR-% (Figure 4), indicating high agreement. Again, the ICC values indicated a very high reliability for the PIPR outcome parameters (PIPR-mm: ICC = 0.83; PIPR-%: ICC = 0.80) (Table 5).

View Article: PubMed Central - PubMed

ABSTRACT

Melanopsin-containing retinal ganglion cells play an important role in the non-image forming effects of light, through their direct projections on brain circuits involved in circadian rhythms, mood and alertness. Individual differences in the functionality of the melanopsin-signaling circuitry can be reliably quantified using the maximum post-illumination pupil response (PIPR) after blue light. Previous protocols for acquiring PIPR relied on the use of mydriatics to dilate the light-exposed eye. However, pharmacological pupil dilation is uncomfortable for the participants and requires ophthalmological expertise. Hence, we here investigated whether an individual’s maximum PIPR can be validly obtained in a protocol that does not use mydriatics but rather increases the intensity of the light stimulus. In 18 participants (5 males, mean age ± SD: 34.6 ± 13.6 years) we evaluated the PIPR after exposure to intensified blue light (550 µW/cm2) provided to an undilated dynamic pupil. The test-retest reliability of the primary PIPR outcome parameter was very high, both between day-to-day assessments (Intraclass Correlation Coefficient (ICC) = 0.85), as well as between winter and summer assessments (ICC = 0.83). Compared to the PIPR obtained with the use of mydriatics and 160 µW/cm2 blue light exposure, the method with intensified light without mydriatics showed almost zero bias according to Bland-Altman plots and had moderate to strong reliability (ICC = 0.67). In conclusion, for PIPR assessments, increasing the light intensity is a feasible and reliable alternative to pupil dilation to relieve the participant’s burden and to allow for performance outside the ophthalmological clinic.

No MeSH data available.