Document Detail

The minimum stimulus energy required to produce a cooling sensation in the human cornea.
MedLine Citation:
PMID:  11563429     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To estimate the minimum stimulus energy required to stimulate the corneal nerves, using a thermally cooling stimulus. METHODS: The localised temperature change produced in the pre-corneal tear film by the air-pulse stimulus of the Non-Contact Corneal Aesthesiometer (NCCA) was analysed using a thermal imaging camera. Assuming that the cornea behaves as a near perfect black-body, the threshold for energy loss was calculated by combining Stefan-Boltzmann's law and Kirchoff's law for imperfections in black-body radiation, taking into account the likely thermal conductivity of the human cornea. RESULTS: The average normal subject has a threshold for detecting a cooling effect when the local corneal tear film surface temperature drops from a mean of 33.2-32.9 degrees C (i.e. 0.3 degrees C), over a 1 mm diameter circular area (0.785 mm2), and a stimulus time duration of 0.9 s. This gives rise to a sensation threshold for perceiving a loss of heat energy of 7.0 ergs, or 7.0 x 10(-7) joules. CONCLUSION: The cornea possesses stimulus specific receptors, which have an exquisite sensitivity to a rapid, thermally cooling stimulus.
P J Murphy; S Patel; P B Morgan; J Marshall
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists)     Volume:  21     ISSN:  0275-5408     ISO Abbreviation:  Ophthalmic Physiol Opt     Publication Date:  2001 Sep 
Date Detail:
Created Date:  2001-09-20     Completed Date:  2001-09-27     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8208839     Medline TA:  Ophthalmic Physiol Opt     Country:  England    
Other Details:
Languages:  eng     Pagination:  407-10     Citation Subset:  IM    
Department of Vision Sciences, Glasgow Caledonian University, Scotland, UK.
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MeSH Terms
Cold Temperature*
Cornea / innervation*
Models, Biological
Physical Stimulation / methods
Sensory Thresholds
Temperature Sense*

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

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