[Diagnostic value of the chromatic contents of fundus photography]

The optical properties of the human lens change with age and are affected by both ocular and systemic diseases. A usual change is a gradual diffuse browning or sclerosis of the lens nucleus. This nuclear sclerosis leads to selective absorption of short wave (blue) light when broad band (white) light is sent into the eye. During fundus photography a light is flashed in front of the eye which enters the pupil and is reflected from the retina to be recorded on film. The light from the flash will pass twice through the optics of the eye where the short wave lengths will be absorbed. A new method has succeeded in describing the correlation between age and the selective absorption of blue light in the ocular lens. Preliminary studies using this method have shown that the ocular lens displays increased "ageing" in diabetic patients which is probably related to the cumulative exposition to hyperglycemia. The advantages of the method are that it uses clinical data already available in patients with retinal diseases and that it is fast, inexpensive, and non-invasive to carry out. The method is another example of the eye as a significant viewer to the study of generalized diseases and their systemic complications.