Evaluation of Human Anterior Lens Capsule Elastic Modulus and Morphology in Different Types of Cataracts Using Nanoindentation
To evaluate and compare the elastic modulus, hardness and mechanical properties of the human anterior lens capsule (ALC) in different types of cataract patients by using nanoindentation device and also to investigate the correlation of these measurements with patient age.
The study evaluated 72 patients having cataract surgery. Patients were investigated in 3 groups. Group 1 consisted of24 patients with normal senile cataract, group 2 patients (n=24) had pseudoexfoliation syndrome(PXF) and group 3 patients (n=24) had dye-enhanced cataract surgery (0.06% Blue Rhexis). ALCs were analyzed by using CSM instrument nanoindentation tester device. Young’s Modulus elasticty was measured by Oliver and Pharr method and capsule stiffness by Martens Hardess method. ALC thickness was measured by Scanning Electron Microscopy.
There was no significant difference in 3 groups regarding age (p=0.997) and ALC thickness (p=0,975). Young’s modulus was 7.53±1.07 Gpa in Group 1, 6.007±1.25 Gpa in Group 2 and 8.12±0.98 Gpa in Group 3. Capsules with PXF were significantly more elastic than the other two groups (p=0.000). Patients with intracameral trypan blue (TB) application (group3) revealed lower elasticity comparing to the normal group (group1) but the difference was not statistically significant (p = 0.94).Mean capsule stiffness was 326.41±98.40 Mpa for Group 1, 210, 5±52.32 Mpa for Group 2 and 315.54±163.15 Mpa for Group 3. PXF group displayed less stiffness comparing to the other two groups (p<0.01).
Capsule thickness displayed an increase correlated with increasing age in all groups. The anterior lens capsules of patients with PXF had more elasticity and less stiffness comparing to the other two groups. Intracameral TB dye application had no effect on capsule elasticity and stiffness.