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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.


Related in: MedlinePlus

Bland-Altman plots for PIPR-mm (left) and PIPR-% (right) between 160 µW/cm2 blue light with mydriatics (160My+) and intensified blue light (550 µW/cm2) with natural pupil (550My−). Differences between the two conditions (i.e., 160My+ minus 550My−) are plotted against the mean of the two measurements. The dotted line represents the bias, i.e., the mean difference between all measurements of 160My+ and 550My−. The dashed lines are the 95% limits of agreement, 95% of the differences between the conditions lies between these lines. The smaller the limits of agreement, the better the agreement between the two measurements.
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biology-05-00034-f002: Bland-Altman plots for PIPR-mm (left) and PIPR-% (right) between 160 µW/cm2 blue light with mydriatics (160My+) and intensified blue light (550 µW/cm2) with natural pupil (550My−). Differences between the two conditions (i.e., 160My+ minus 550My−) are plotted against the mean of the two measurements. The dotted line represents the bias, i.e., the mean difference between all measurements of 160My+ and 550My−. The dashed lines are the 95% limits of agreement, 95% of the differences between the conditions lies between these lines. The smaller the limits of agreement, the better the agreement between the two measurements.

Mentions: The Bland-Altman plots indicated almost zero bias between 160My+ and 550My− for PIPR-mm and PIPR-% (Figure 2) indicating high agreement. When comparing the condition 160My+ to the condition 550My−, the ICC values indicate a moderate to strong agreement for the PIPR outcome parameters (PIPR-mm: ICC = 0.67; PIPR-%: ICC = 0.58). The ICC of 0.77 indicated a strong agreement between these conditions for the post-blue pupil diameter, which was confirmed by an almost-zero Bland-Altman bias.


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 160 µW/cm2 blue light with mydriatics (160My+) and intensified blue light (550 µW/cm2) with natural pupil (550My−). Differences between the two conditions (i.e., 160My+ minus 550My−) are plotted against the mean of the two measurements. The dotted line represents the bias, i.e., the mean difference between all measurements of 160My+ and 550My−. The dashed lines are the 95% limits of agreement, 95% of the differences between the conditions lies between these lines. The smaller the limits of agreement, the better the agreement between the two measurements.
© Copyright Policy
Related In: Results  -  Collection

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

biology-05-00034-f002: Bland-Altman plots for PIPR-mm (left) and PIPR-% (right) between 160 µW/cm2 blue light with mydriatics (160My+) and intensified blue light (550 µW/cm2) with natural pupil (550My−). Differences between the two conditions (i.e., 160My+ minus 550My−) are plotted against the mean of the two measurements. The dotted line represents the bias, i.e., the mean difference between all measurements of 160My+ and 550My−. The dashed lines are the 95% limits of agreement, 95% of the differences between the conditions lies between these lines. The smaller the limits of agreement, the better the agreement between the two measurements.
Mentions: The Bland-Altman plots indicated almost zero bias between 160My+ and 550My− for PIPR-mm and PIPR-% (Figure 2) indicating high agreement. When comparing the condition 160My+ to the condition 550My−, the ICC values indicate a moderate to strong agreement for the PIPR outcome parameters (PIPR-mm: ICC = 0.67; PIPR-%: ICC = 0.58). The ICC of 0.77 indicated a strong agreement between these conditions for the post-blue pupil diameter, which was confirmed by an almost-zero Bland-Altman bias.

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.


Related in: MedlinePlus