Title : Biomechanical and electron microscopic appearance changes of the anterior lens capsule after indocyanine green staining
Abstract:
Purpose: To assess potential changes in lens capsule biomechanical and electron microscopic appearance after staining with indocyanine green (ICG).
Setting: Department of Ophthalmology, Beijing Tongren hospital, Capital Medical University, China.
Design: Experimental study.
Methods: A total of 40 anterior capsules were obtained during cataract surgery, and 20 anterior capsules were randomly divided into 2 groups.Two bands of the same size were prepared for each capsule. One was stained with ICG for 10 seconds(Group 1) or 1 min(Group 2), and the other was used as a control.The mechanical property measurement was carried out on two groups of samples using a nanoindentation instrument.The other 20 cases of anterior capsule were subjected to ultrastructural analysis using Scanning electron microscopy(SEM) and transmission electron microscopy(TEM).
Results: The average elastic modulus (4.16±0.51GPa vs. 4.21±0.56GPa, p=0.69) and the average stiffness (0.17±0.03GPa vs. 0.18±0.04 GPa, p=0.16) of the stained capsule fragments in Group 1 were not significantly different from those in the control group.The average elastic modulus (4.48±0.75GPa vs.4.08±0.49 GPa, p=0.04) and average stiffness (0.19±0.03 GPa vs.0.15±0.02 GPa, p=0.01) of the stained capsule fragments in Group 2 were significantly higher than those in the control group, with statistically significant differences.Electron microscope observation showed that the cells were swollen, mitochondrial outer membrane was broken, part of the endoplasmic reticulum was vacuolized, the surface fibers of the capsule were disordered, and the fiber structures were fused and rigid after ICG staining.
Conclusion: ICG staining significantly affects the mechanical properties and ultrastructure of the human lens capsule.The alteration of the fiber structure on the surface of the capsule might be the cause of the mechanical changes in the capsule.
