The effects of vital dyes on mechanical properties of the human anterior lens capsule

Purpose: The purpose of this study was to evaluate the mechanical effects of vital dyes on the anterior lens capsule via the nanoindentation method. Methods: Twenty anterior lens capsules of 20 different patients were dissected into four equal fragments. Each fragment was stained separately with dyes for intraocular surgeries, such as trypan blue 0.06% (TB), brilliant blue 0.025% (BB), and indocyanine green 0.05% (ICG), for 1 min. The remaining fragment was assessed as an untreated control group. The alterations on the mechanical characteristics of the anterior lens capsule were evaluated using a nanoindentation testing device with Oliver-Pharr and Martens hardness methods. Results: The mean values of elasticity were 7.842 +/- 0.55 GPa for capsules fragments stained with TB (P < 0.05), 8.407 +/- 0.82 GPa for capsules fragments stained with BB (P < 0.05), 8.557 +/- 0.60 GPa for ICG (P < 0.05), and 6.09 +/- 0.57 GPa for the untreated control group. The mean values of stiffness were 299.7 +/- 47 MPa for TB (P < 0.05), 317.9 +/- 34 MPa for BB (P < 0.05), 331.8 +/- 48 MPa for ICG (P < 0.05), and 229.85 +/- 44 MPa for the untreated control group. The elasticity of the capsules statistically decreased in comparison to the control group, and the capsule stiffness showed a statistically significant increase in comparison to the untreated controls. Conclusion: The mechanical characteristics of the human anterior lens capsule were affected in association with the alterations in the elasticity and stiffness properties of the capsule as a result of exposure to three different dyes.