[Methods for in vivo measurement of light transparency in the human crystalline lens]

A method for the in vivo measurement of light transparency of the human crystalline lens, based on the measurement of the blue and red light threshold radiance, in presented. The threshold limit values for radiances of 477 nm (blue) and 620 nm (red) were measured for people at age from 17 to 66 years old without cataract. The people recognised the geometric figures by left and right eye separately, after being adapted to darkness. The radiance of the figures was changed smoothly by ADM adaptometer. The threshold limit values were measured several times for each eye. For each eye the average of the threshold limit values for radiances of 620 nm and 477 nm and their quotient were calculated. Values of these quotients practically did not change for young eyes (to 32 years old) and they decreased for older eyes. These results indicate the increase of the threshold radiance of 477 nm in relation to threshold radiance of 620 nm for older people, and this means the reduction of the crystalline lens transparency for blue light in relation to red one as they grow old. It seems that the reduction should precede the development of cataractous changes and this fact may be used in the diagnostics of precataractous states.