Corneal biomechanics: Where are we?

摘要

Corneal biomechanics emerged as a very hot topic forresearch in Ophthalmology. 1,2 In this issue, Sharifipour andcoworkers 3 present an observational cross-sectional study inhealthy individuals that evaluated the correlations of cornealviscoelastic properties measured by the Ocular Response Ana-lyzer (ORA, Reichert, Buffalo, NY) with central corneal thick-ness (CCT) in different age groups. In this study, cornealhysteresis (CH) and corneal resistance factor (CRF) had a sig-nificant negative correlation with age (P < 0.001). Other studieshad already demonstrated that CH and CRF have a negativecorrelationwithageanda positivecorrelationwithCCT. 4 Whilestatistical methodology was done properly in these studies, it isvery important to note that CH and CRF do not express stiffnessor the stressestrain behavior of corneal tissue. It is well recog-nized that corneal stiffness increases with age due to enzymaticpathwayssuchastransglutaminaseandlysyloxidase,generatingnatural collagen crosslinking. 5 In agreement with such concept,Elsheikh and coworkers analyzed human corneal specimensranging in age between 50 and 95 years with an inflation test,findinga significantincrease instiffnessassociated with ageandalso with the load rate.