Document Detail

The effect of stimulus duration on tonic accommodation and tonic vergence.
MedLine Citation:
PMID:  2381686     Owner:  NLM     Status:  MEDLINE    
Changes in tonic accommodation and tonic vergence were studied as a function of stimulus duration and time after near fixation. Thirteen visually normal young adults each participated in experimental sessions comprising each of 12 combinations of stimulus type (accommodative or vergence) and stimulus duration (0.25, 0.5, 1, 2, 4, or 8 min). During each session, measurements were made of either tonic accommodation or tonic vergence 30 s before stimulus onset and at 0.5, 2, 4, 6, 8, 10, 12, and 14 min after stimulus offset. The stimulus (a high contrast reduced Snellen visual acuity chart) was viewed monocularly at the accommodative nearpoint and binocularly through pinholes at the fusional nearpoint on the accommodative and vergence sessions, respectively. For tonic accommodation, stimulus duration had no significant effect on either the magnitude of the aftereffect or its rate of decay. For tonic vergence however, the aftereffect was larger and had a slower rate of decay as stimulus duration increased. The results suggest that the adaptive mechanisms within the two systems have different time constants.
S K Fisher; K J Ciuffreda; J E Bird
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Optometry and vision science : official publication of the American Academy of Optometry     Volume:  67     ISSN:  1040-5488     ISO Abbreviation:  Optom Vis Sci     Publication Date:  1990 Jun 
Date Detail:
Created Date:  1990-09-13     Completed Date:  1990-09-13     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8904931     Medline TA:  Optom Vis Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  441-9     Citation Subset:  IM    
Ocular Motility Laboratory, New England College of Optometry, Boston, Massachusetts.
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MeSH Terms
Accommodation, Ocular / physiology*
Convergence, Ocular / physiology*
Eye Movements / physiology*
Photic Stimulation*
Random Allocation
Time Factors
Vision, Binocular
Vision, Monocular
Visual Acuity
Grant Support

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

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