Protein size resolution in human eye lenses by dynamic light scattering after in vivo measurements.

Dynamic light scattering (DLS) measurements were conducted with lowest intensity levels on human eye lenses (3.2 mW/cm2) within measurement times of 3-5 s. A characterisation of the human eye under in-vivo conditions along the optical axis is given and a careful interpretation of the data is made, referring not only to in-vitro results of investigated solutions of lens chemistry and various crystallin fractions but also to measurements performed on intact human lenses under various scattering angles. The clinical study was expanded to 79 subjects with ages varying from 9 to 85 years with no serious diseases of the ocular lenses. A normalisation of Scheimpflug photography density data to the data obtained by DLS enables comparison of the two techniques and shows good agreement. The bimodal character of the viscoelastic properties of healthy eye lenses was confirmed; with an assumed viscosity of 2 cP, the mean size parameter of the smaller component is 5.13 +/- 1.6 nm and of the polymeric fraction 690 nm.