Photographic investigation of the human lens and cataract.

Slit-image photography of the anterior segment of the eye can provide important information about the dimensions and optical densities of the refractive structures. It is crucial that the slit-image photograph be in perfect focus and that the slit-beam cut in exactly the same section (along the optic axis) on each occasion. The equipment, principles and techniques which make such precision slit-imagephotography possible are discussed. Clinical and research applications, especially regarding the human lens and cataract, are summarized.