Journal article
Studying the effect of iris mechanics on the pupillary light reflex using brimonidine-induced anisocoria
Investigative ophthalmology & visual science, Vol.54(4), pp.2951-2958
04/26/2013
DOI: 10.1167/iovs.12-10916
PMCID: PMC3638661
PMID: 23513058
Abstract
To study and correct for the limiting effect of iris mechanics on the amplitude of light-evoked pupil contractions in order to derive a more clinically accurate assessment of afferent input to the visual system. Transient pupil responses were recorded to a series of 1-second red Ganzfeld light stimuli with a stepwise increase in stimulus intensity using a binocular infrared computerized pupillometer. One eye of eight healthy subjects was treated with 0.2% brimonidine tartrate ophthalmic solution to induce pupil size reduction. The amount of pupil contraction as a function of stimulus intensity was compared between the brimonidine-treated, miotic eye and the untreated eye. BRIMONIDINE TREATMENT PRODUCED SIGNIFICANT REDUCTION IN PUPIL SIZE IN HEALTHY SUBJECTS (MEAN REDUCTION IN PUPIL SIZE: 1.78 ± 0.35 mm, P < 0.05). For increasing light intensity, the treated pupil started to show reduced pupil contractions compared with the contralateral untreated pupil when the peak of pupil contraction reached an average pupil size of 3.25 ± 0.61 mm (range, 2.38-4.44 mm). When measured by percent pupil contraction (contraction amplitude/baseline pupil diameter), the pupil response as a function of stimulus intensity in the treated, miotic eye did not differ from that in the untreated eye. Iris mechanics limits the amount of pupil contraction and can act to reduce the assessed neuronal integration of the pupil light reflex. Pupil response assessed by using percent contraction amplitude is least affected by mechanical effects and provides a more accurate approximation of afferent input.
Details
- Title: Subtitle
- Studying the effect of iris mechanics on the pupillary light reflex using brimonidine-induced anisocoria
- Creators
- Yanjun Chen - Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, USA. ychen@ophth.wisc.eduRandy H Kardon
- Resource Type
- Journal article
- Publication Details
- Investigative ophthalmology & visual science, Vol.54(4), pp.2951-2958
- DOI
- 10.1167/iovs.12-10916
- PMID
- 23513058
- PMCID
- PMC3638661
- NLM abbreviation
- Invest Ophthalmol Vis Sci
- ISSN
- 0146-0404
- eISSN
- 1552-5783
- Publisher
- United States
- Grant note
- UL1 TR000427 / NCATS NIH HHS UL1 RR025011 / NCRR NIH HHS 1 UL 1 RR025011 / NCRR NIH HHS
- Language
- English
- Date published
- 04/26/2013
- Academic Unit
- Iowa Neuroscience Institute; Ophthalmology and Visual Sciences
- Record Identifier
- 9983979967302771
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