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The pupil in pupillometry ‐ to dilate or not to dilate ..
Author(s) -
NISSEN C,
SANDER B,
LUNDANDERSEN H
Publication year - 2011
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2011.2264.x
Subject(s) - pupil , pupillometry , melanopsin , pupillary light reflex , pupil diameter , ophthalmology , blue light , intrinsically photosensitive retinal ganglion cells , contraction (grammar) , pupillary response , stimulus (psychology) , red light , luminance , mydriasis , medicine , optics , retinal , psychology , physics , retinal ganglion cell , biology , photopigment , botany , psychotherapist
Purpose To evaluate the influence of the size of the light exposed pupil in one eye on the consensual reflex in the other. Methods Using a prototype chromatic pupillometer, the left eye in each of 10 healthy subjects was exposed to 20 s of monochromatic light of luminance 300cd/m2, first red (660nm)and in a following session, blue (470 nm) light. The consensual contraction of the right pupil was measured simulataneusly before, during and after light exposure. Tropicamid or pilocarpine was subsequently instilled into the left eye and the entire sequence repeated after allowing the left pupil to dilate or contract. Results The AUC (Area Under the Curve, i.e. the "integral" of contraction amplitude versus time) of the right pupil was determined for each individual sequence. Prior dilatation of the left pupil augmented the post light AUC to blue (p<0.0001), but not to red light. The contraction during light exposure did not change. Prior contraction of the left pupil decreased the late (10‐30s) post‐stimulus AUC to blue light (p<0.02), but not any other AUC. Conclusion The size of the light exposed pupil influences the magnitude of the response to blue, but not not to red light of the contralateral pupil. Thus prior dilatation may prove useful, when the response to blue light (as a marker of melanopsin containing retinal ganglion cell function) is of interest, especially when this response is weak. Prior dilatation may also be useful in exchanging long duration of stimulus with short duration, thus making the examination faster, less prone to artefacts and not least, less tiresom to the patient.