Document Detail


Comparison of elevation, curvature, and power descriptors for corneal topographic mapping.
MedLine Citation:
PMID:  8587768     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Corneal topography systems sample thousands of surface points and from these data different descriptors are derived to create maps of the cornea. Without visualizing and comparing the maps, it is difficult to appreciate the implications of each descriptor for mapping. We created and compared several maps of an ellipsotoric cornea based on the following surface descriptors: relative elevation, dioptric curvature, and refractive power. Each map presented a different picture of the same cornea. Only elevation maps show true topography but must be calculated relative to an appropriate reference surface to reveal important features. Axial and to a greater degree instantaneous curvature maps bring out optically significant shape asymmetries but misrepresent refractive power away from the apex. Ray tracing maps display optical properties that are not apparent from the elevation or curvature maps, including spherical aberration. Oblique astigmatism can be described using a pair of maps for the sagittal and tangential powers at each surface point. A knowledge of these principles is necessary to interpret color maps of the corneal surface correctly.
Authors:
T O Salmon; D G Horner
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Optometry and vision science : official publication of the American Academy of Optometry     Volume:  72     ISSN:  1040-5488     ISO Abbreviation:  Optom Vis Sci     Publication Date:  1995 Nov 
Date Detail:
Created Date:  1996-03-27     Completed Date:  1996-03-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8904931     Medline TA:  Optom Vis Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  800-8     Citation Subset:  IM    
Affiliation:
School of Optometry, Indiana University, Bloomington, USA.
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MeSH Terms
Descriptor/Qualifier:
Cornea / anatomy & histology*
Humans
Image Processing, Computer-Assisted* / standards
Mathematics
Models, Biological*

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


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