| The measurement of pupil cycling time. | |
| | |
MedLine Citation:
|
PMID: 11127569 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
PURPOSE: To assess the influence of pupil size on pupil cycling time (PCT), a measure which may be elongated in cases of neurological disease. METHOD: Clinically, pupil "cycling" is produced by focusing a slit-lamp beam on the pupil margin. A rhythmic contraction and dilation of the pupil is produced, as changes in pupil size alternately prevent and allow the light beam to reach the retina. In this study, however, the light beam was controlled electronically so that cycling could be produced around different pupil sizes. Measurements of the variation of PCT with pupil size were taken from 22 young normal subjects. RESULTS: PCT was seen to depend upon pupil size, increasing monotonically but non-linearly as size increased. The wave-form of pupil cycling is typically sawtooth, contraction being much faster than dilation. There was considerable variation amongst subjects in the range of pupil sizes where pupil cycling could be elicited. CONCLUSIONS: The results point to the need for a standardised procedure for the measurement of cycling time, because differences in clinical conditions will themselves influence pupil size, as will other external variables such as ambient light level. The results also bring into question neurological explanations for increased PCT in those diseases where pupil size is affected, because normal subjects have PCTs well beyond the accepted limits of normality when their pupils are enlarged. |
| | |
Authors:
|
P A Howarth; G Heron; L Whittaker |
Related Documents
:
|
11876329 - Calculated impact of higher-order monochromatic aberrations on retinal image quality in... 6624409 - Accommodation as the primary cause of low-luminance myopia. experimental evidence. 495779 - Static and kinetic properties of the dolphin pupil. 21967449 - (mis)perception of sleep in insomnia: a puzzle and a resolution. 20725339 - Artificial pupils and maxwellian view. 10506269 - Utility of pupillary dilation for detecting leukocoria in patients with retinoblastoma. 17952009 - Long-term fluctuation of standard automatic perimetry, pulsar perimetry and frequency-d... 7191499 - Presumably azorean disease in a presumably non-portuguese family. 16888039 - The significance of direct sunlight and polarized skylight in the ant's celestial syste... |
Publication Detail:
|
Type: Journal Article |
Journal Detail:
|
Title: Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv für klinische und experimentelle Ophthalmologie Volume: 238 ISSN: 0721-832X ISO Abbreviation: Graefes Arch. Clin. Exp. Ophthalmol. Publication Date: 2000 Oct |
Date Detail:
|
Created Date: 2000-12-20 Completed Date: 2001-02-01 Revised Date: 2004-11-17 |
Medline Journal Info:
|
Nlm Unique ID: 8205248 Medline TA: Graefes Arch Clin Exp Ophthalmol Country: Germany |
Other Details:
|
Languages: eng Pagination: 826-32 Citation Subset: IM |
Affiliation:
|
Department of Human Sciences, Loughborough University, UK. p.a.howarth@lboro.ac.uk |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Adolescent Adult Diagnostic Techniques, Ophthalmological Female Humans Light Male Pupil / physiology* Reflex, Pupillary / physiology* Time Factors |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Manifest diabetes and keratoconus: a retrospective case-control study.
Next Document: Ocular and systemic features of Peters' anomaly.