Effect of trypan blue on the elasticity of the human anterior lens capsule

PURPOSE: To evaluate the effect of trypan blue (VisionBlue) staining on the elastic properties of the human anterior lens capsule. SETTING: Center for Vision Science, Ruhr University Eye Hospital, Bochum, Germany. METHODS: Nineteen anterior capsules were obtained from 19 human eyes at the time of cataract operation. Two same-size strips were prepared from each capsule; 1 was exposed to trypan blue staining for 10 seconds, and the other was a control. The elasticity measurements were performed on both specimens using a modified rheometer. RESULTS: The mean age of the patients was 75.3 years +/- 13.3 (SD) (range 35 to 89 years). Sixty-three measurements of 19 suitable specimen pairs were performed. In 13 pairs, the elasticity measurements were eligible for statistical analysis. The stress value at the tearing point was statistically significantly lower in the treated group (mean 169 +/- 55 Pa) than in the control group without staining (mean 252 +/- 67 Pa) (P=.023). The difference in stress between the stained and control samples at 3 seconds and 5 seconds was not statistically significant (P=.093 versus P=.316). Dynamic frequency sweep measurements showed a statistically significant elevation of the viscosity modulus in the samples stained with trypan blue. CONCLUSIONS: Trypan blue staining affected the biomechanical properties of the human lens capsule and led to a significant reduction in elasticity and an increase in stiffness. These results confirm clinical reports of changes in the capsule by dye and should be taken into consideration in dye-enhanced cataract surgery.