Determining Elastic Modulus of Descemet Membrane Stained With Trypan Blue Using Atomic Force Microscopy
To evaluate the effect of trypan blue on biomechanical property of Descemet’s membrane(DM) using atomic force microscopy.
Experimental Study. Human research corneas were collected from the Michigan Eye Bank, USA. The Descemet’s membrane was removed surgically and divided into two halves. One half was stained with trypan blue and the unstained half served as control. The DM was washed in sterile, balance salt solution, and was analyzed using an atomic force microscope. For the measurement of the Young’s modulus of the elasticity force distance curves were obtained using silicon nitride cantilever tip in contact mode. Data were analyzed using Hertzein model for evaluation of young’s modulus of elasticity.
Trypan blue stained DM showed significantly (p<0.05) increased value of the young’s modulus of elasticity(i.e. increased tissue stiffness) when compared to unstained DM. During Descemet’s stripping surgery(DSAEK and DMEK), it is a routine practice to stain the DM in order to improve visibility. However, the results of this study suggest that though it improves visibility, staining makes the DM more brittle and prone to breakage while stripping it. This may lead to incomplete removal of the DM.
Descemet’s membrane stained with the trypan blue showed increased Young’s modulus of elasticity indicating increased stiffness. For the surgeon this indicates increased brittleness of the DM during stripping manouevres.