Document Detail

Compensation for light loss due to filtering by macular pigment: relation to hue cancellation.
MedLine Citation:
PMID:  17470235     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: A long-standing question in colour vision research is how the visual system is able to correct for the significant absorbance of short wave light by the crystalline lens and macular pigment (MP). Such compensation must be required in order to maintain colour constancy across the retina where MP levels are changing quickly and dramatically. OBJECTIVE: We studied this compensation mechanism by measuring MP spatial density profiles and hue cancellation functions across the central retina in a sample of six young healthy subjects. METHOD: Yellow (Y, 575 nm)/blue (B, 440 nm) and red (R, 600 nm)/green (G, 501 nm) cancellation functions were obtained at 0, 1, 1.75, 3 and 7 degrees eccentricity. The MP optical density at 460 nm was measured at these same eccentricities using heterochromatic flicker photometry. One subject was assessed repeatedly over a 4-month period during daily supplementation with 30 mg of lutein (L). RESULTS: Hue cancellation values for the Y/B system did not change across the retina (r = 0.09). In contrast, R/G sensitivity changed as a direct function of MP absorbance (r = 0.99). The Y/B values did not change in the one subject supplemented with 30 mg L daily, despite increases in MP of about 50% over 4 months. CONCLUSIONS: Despite large variations in MP across the retina, hue cancellation values for the Y-B system across the central retina were constant. For example, one subject's MP density declined from a central peak of 0.99 to near zero at 7 degrees (near 90% transmission difference) yet thresholds for the Y/B system were unaffected. In contrast, the G lobe of the R/G system was directly correlated with MP density. Taken together, these results confirm that the Y/B system compensates for MP density, but the R/G system does not.
James M Stringham; Billy R Hammond
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists)     Volume:  27     ISSN:  0275-5408     ISO Abbreviation:  Ophthalmic Physiol Opt     Publication Date:  2007 May 
Date Detail:
Created Date:  2007-05-01     Completed Date:  2007-08-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8208839     Medline TA:  Ophthalmic Physiol Opt     Country:  England    
Other Details:
Languages:  eng     Pagination:  232-7     Citation Subset:  IM    
Vision Science Laboratory, University of Georgia, Athens, GA 30602-3013, USA.
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MeSH Terms
Adaptation, Ocular / physiology*
Color Perception*
Macula Lutea / physiology*
Models, Biological
Retinal Pigments / physiology*
Reg. No./Substance:
0/Retinal Pigments

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

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