Real light scatter in the human crystalline lens.

A comparison is made between the luminances of slit-lamp images of the normal human lens in frontal view with plane polarized light, when one ocular is provided with an analyzer and the other with variable neutral density filters, the light source being polarized perpendicularly to the direction of the analyzer. The amount of extinguished light is significantly larger as seen in the former, and rises systematically with age. The effect of varying the spectral composition of the illumination is also examined. What is conventionally referred to as scattered light appears to be made up of at least two separate components. The effect which this may have for our interpretation of pathological images is discussed.