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Comparison of factors that influence the measurement of corneal hysteresis in vivo and in vitro.
MedLine Citation:
PMID:  21457485     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Purpose:  The purpose of this study was to compare measurements of corneal hysteresis (CH) obtained in vivo, with similar measurements from excised human eyes and from excised human corneas mounted in an artificial anterior chamber. Methods:  Corneal hysteresis was measured using an ocular response analyser (Reichert Ophthalmic Instruments) from three groups: 53 healthy normal corneas of fifty-three patients, six excised eyes and 17 excised corneas. Results:  In vivo, it was found that CH was independent of gender, age and mean spherical equivalent, but has a significant inverse relationship with intraocular pressure (IOP(cc) ) (r = 0.53; p < 0.0001). However, there was no correlation between CH and IOP(G) (r = 0.10; p = 461). The same inverse relationship with IOP(cc) was recorded in intact, excised eyes (r = 0.74; p < 0.0001), with no significant differences between the behaviour each individual eye. Excised corneas also showed an inverse relationship between CH and trans-corneal pressure (r = 0.72; p < 0.0001), but the measured values of CH were lower than those recorded in vivo and from intact globes. In both excised eyes and excised corneas, we found a significant correlation between CH and central corneal thickness [r = 0.86; p < 0.0001 and r = 0.611; p < 0.0005 (respectively)]. Conclusion:  The in vitro results indicate that every normal human eye at physiological hydration shows an identical dependence of CH on IOP(cc) , the same dependence as is observed in vivo. This therefore would appear to be an intrinsic response of the tissue to a change in IOP. However, it is possible that the lower values of CH recorded from excised corneas reflect the influence of the artificial chamber replacing the eye globe, so in vivo values of CH may be influenced to some extent by the presence of the other components of the eye.
Authors:
Tariq A Alhamad; Keith M Meek
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-4-1
Journal Detail:
Title:  Acta ophthalmologica     Volume:  -     ISSN:  1755-3768     ISO Abbreviation:  -     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-4-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101468102     Medline TA:  Acta Ophthalmol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
© 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.
Affiliation:
Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK.
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