Document Detail

The form of the human pupil.
MedLine Citation:
PMID:  7660606     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to characterize the form of the pupil in normal human subjects. Using a modified slitlamp, photographs of pupils were taken in steady illumination and 10-20 sec after darkness. Transparencies were projected and digitized, and the pupil margin was represented as a circular Fourier series. Best-fit ellipses were also determined. The placement of the pupil relative to the limbus was determined in a number of subjects. Results from 23 subjects indicated that in both darkness and light, average pupil noncircularity was 0.0166. (A value of 0.0200 is easy to detect with the unaided eye from the photographs.) On average, the best-fit ellipse accounted for about half of the noncircularity (59.6% in darkness; 47.7% in light). Most of the contribution to shape was made by the first 4 or 5 harmonics. Shapes were usually stable within a session and could remain fairly stable for at least a year; however, shapes for different subjects were not very similar, especially in the light. (Average pairwise similarity: 0.106 in darkness; 0.034 in light; similarity can have values from -1 to 1.) For a given subject, shapes in light and dark were often fairly similar (average similarity 0.260), but there were systematic differences: in eyes where the ellipse contributed > 20% of noncircularity, ellipse major axes clustered around vertical in darkness, and horizontal in light, implying greater contraction near the vertical meridian. Even pupils with little elliptical contribution turned out to contract more near the vertical meridian. There was some tendency for left and right eyes of an individual to show mirror symmetry of shape. In the dark, pupils were located 0.27 +/- 0.09 mm nasal and 0.20 +/- 0.15 mm superior to the limbus center, and usually moved slightly further nasal or superior in the light. Noncircularity increased with age (0.0015/decade). It was concluded that pupils show individuality of shape, with significant regularities within and across subjects.
H J Wyatt
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Vision research     Volume:  35     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  1995 Jul 
Date Detail:
Created Date:  1995-10-03     Completed Date:  1995-10-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  2021-36     Citation Subset:  IM    
Schnurmacher Institute for Vision Research, State University of New York, State College of Optometry, NY 10010, USA.
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MeSH Terms
Aging / physiology
Iris / anatomy & histology*
Middle Aged
Models, Biological
Pupil / physiology*
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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