Aging lens undergoes the changes in the amount of water soluble lens proteins and their redistribution from low molecular weight to high. This results in the development of high molecular weight aggregates, which change the lens transparency, increase light scattering and contribute to the hardening of the lens. All these disturbances cause changes in ultrasound attenuation. Hardness of the cataractous lens is one of the major factors influencing the suitability of a patient for fhacoemulsification. Age and nuclear color have been shown to be good clinical markers of lens hardness, but there is a need of more quantitative and objective examination method. In this work a new methodics of assessement of eye lens hardness in vitro was developed, the hardness of dogs and human eye lenses was assessed experimentally, the investigation of ultrasound attenuation coefficient, the amount of water soluble lens proteins and their distribution to the fractions of different molecular weight was performed. A strong correlation between lens hardness and ultrasound attenuation was investigated. The results enable to evaluate lens hardness pre-operatively and non invasively and help surgeons when choosing patients to the phacoemulsification method of cataract extraction. The performed investigation confirmed that the opacification of the lens is due to the changes in the amount of water soluble lens proteins and the presence of high molecular weight compounds, which disturb the light... [to full text]