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Comparative Study
. 2011 Nov;94(6):545-8.
doi: 10.1111/j.1444-0938.2011.00636.x. Epub 2011 Sep 20.

Influence of field size on pupil diameter under photopic and mesopic light levels

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Free article
Comparative Study

Influence of field size on pupil diameter under photopic and mesopic light levels

David A Atchison et al. Clin Exp Optom. 2011 Nov.
Free article

Abstract

Purpose: We investigated the interaction between adapting field size and luminance on pupil diameter when cones alone (photopic) or rods and cones (mesopic) were active.

Method: Circular achromatic targets (1° to 24° diameter) were presented to eight young participants on a rectangular projector screen. The accommodative influence on pupil diameter was minimised using cycloplegia in the foveally fixating right eye and the consensual pupillary reflex was measured in the left eye. Target luminance was adjusted for each stimulus such that corneal flux density (product of field area and luminance) was constant at 3,600 cd.deg(2) m(-2) (photopic condition) and 1.49 cd.deg(2) m(-2) (mesopic condition).

Results: There were no statistically significant effects of adaptive field size on pupil diameter for either condition.

Conclusion: If corneal flux density is kept constant, there will be no change in pupil diameter as the size of the stimulus field increases at either mesopic or photopic lighting levels up to at least 24° diameter.

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