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Janis B. Orr, Lyle S. Gray, Dirk Seidel, Mhairi Day; The Effect of Target Luminance, Target Vergence and Refractive Correction upon Pupil Diameter. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2851. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the effect of refractive correction, target luminance and target vergence upon pupil diameter in emmetropic (EMM), myopic (MYO) and hyperopic (HYP) subjects.
Sixty visually normal subjects (mean± SD age = 22.35 ± 4.13 years) with refractive errors ranging from -10.00D to +6.00D (MSE) participated with informed consent in the experiment. Subjects viewed a 6/12 Snellen equivalent target, illuminated by a slide projector in a +5D Badal optical system, at accommodation stimulus levels of 0D and 3D. Target luminance levels of 12, 99, 188, 388, 999, 1990 and 4111cd/m2 were presented in increasing order of luminance, using slides containing ND filters. One minute of adaptation was allowed before readings were obtained at each luminance level. Continuous recordings of monocular entrance pupil diameter of 1minute duration using the Power Refractor II aligned perpendicularly to the viewing system via a hot mirror. Measurements were obtained from the right eye under two conditions: refractive error not corrected (NC); refractive error corrected with daily disposable soft contact lenses (C).
Mean pupil diameter decreased significantly with increasing target luminance in both NC and C conditions, for EMMs, MYOs and HYPs at both accommodation stimulus levels (ANOVA, p<0.005 for all comparisons). There was no significant difference in mean pupil diameter between refractive groups at either 0D or 3D, irrespective of whether refraction was corrected. Mean pupil diameter was significantly smaller for the 3D compared to 0D for target luminance levels of 12, 99, 188, 388 and 4111cd/m2 (ANOVA, p<0.05) but were equivalent at 999 and 1990cd/m2. At low luminance levels (12 & 99cd/m2) NC pupil diameter was significantly smaller than C pupil diameter in HYP, whereas NC and C pupil diameters were equivalent in MYO.
Target luminance is the primary determinant of pupil diameter at high luminance levels. At low luminance levels, near induced pupil miosis is evident in all refractive groups. The influence of refractive correction is found at low luminance levels only in the HYP. The influence of pupil diameter upon refractive development is unlikely to be significant.
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