Document Detail

Rod-mediated increment threshold functions in infants.
MedLine Citation:
PMID:  11095637     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To obtain and analyze scotopic increment threshold functions to test the hypothesis that rod photoreceptor immaturity accounts for the elevation of infants' over controls' dark-adapted thresholds and elevation of parafoveal over peripheral thresholds in infants. METHODS: Using a preferential looking method, thresholds for detection of 2(o), 50 msec, blue stimuli presented 10(o) (parafoveal) or 30(o) (peripheral) eccentric were measured in the dark and in the presence of steady red backgrounds. Ten 10-week-old infants and four control subjects (8-35 years) were tested. To evaluate pre- and postadaptation site determinants of threshold, a model of the increment threshold function was fit to the data, and the dark-adapted threshold (T(D)) and eigengrau (A(O)) were calculated. The values of T(D) and A(O) were compared between infants and controls and between parafoveal and peripheral eccentricities. RESULTS: At both parafoveal and peripheral eccentricities, infants' values of T(D) and A(O) were significantly higher than those of controls. The locus of the coordinates (A(O), T(D)) differed significantly between parafoveal and peripheral eccentricities. In every infant, the parafoveal value of T(D) was higher (by 0.3-0.6 log unit) and A(O) lower (by 0.2-0.5 log unit) than the peripheral value, whereas controls had no difference in T(D) and A(O) at the two eccentricities. CONCLUSIONS: The results indicate that both receptoral and postreceptoral immaturities have a role in the elevation of infants' over controls' thresholds. In infants, rod photoreceptor immaturity before the site of adaptation accounts for elevation of parafoveal over peripheral thresholds.
R M Hansen; A B Fulton
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  41     ISSN:  0146-0404     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2000 Dec 
Date Detail:
Created Date:  2000-12-12     Completed Date:  2000-12-22     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  4347-52     Citation Subset:  IM    
Department of Ophthalmology, Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
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MeSH Terms
Dark Adaptation
Retinal Rod Photoreceptor Cells / growth & development,  physiology*
Sensory Thresholds / physiology
Visual Perception / physiology*
Grant Support

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