One other form of eye change requires attention--namely, retinal changes due to circulatory disturbances. In an advanced case the whole picture is one of severe albuminuric retinitis, but in the earlier stages some engorgement of the vessels without alteration of the surrounding tissue is seen. Elschnig[21] associated this alteration in the vessels of the eye with vaso-motor changes caused by direct action of the poison, producing a vascular constriction or dilatation, and is inclined to regard the kidney disease frequently associated with this condition of the eye as something quite apart. He would regard the two affections as independent, and merely correlated through their common origin--lead intoxication. It has even been suggested by some observers that the change in the eye is secondary to cerebral œdema. Thus Mannaberg[22] regards the encephalitis of saturnine origin as associated with chronic œdema of the brain and spinal cord, which thus produces reflex irritation of the nervous system of the eye. Bikler[23] and Weber[24] consider the symptoms as circulatory. From whatever cause the disease is set up, sooner or later changes in the form of obliterative arteritis take place, with gradual but ultimately complete loss of vision. There are said to be no characteristic eye symptoms in acute cases of lead poisoning, whereas with chronic lead poisoning in many cases there is central and peripheral affection. The affections may be further divided into subjective and objective. Many of the subjective symptoms, such as loss of sight and blindness, are associated with definite eye lesions, which may be seen with the ophthalmoscope, but other definitely objective lesions may be present without any influence on sight to commence with. Folker[25] describes five cases of lead amblyopia in lead-workers from a pottery district, in all of which there was a peculiar symptom--the gradual failing of sight associated with colour flashes. When examined, the discs were described as white, and the vessels small. Lockhart Gibson[26], in describing the cases of eye disease amongst the children in Queensland, found one symptom apparently in all the eyes examined--namely, great swelling of the discs. This swelling of the discs might be accompanied with no loss of sight whatever, and at other times had been accompanied with defective sight for many months previously. Some of the discs were excessively swollen. There were also to be seen patches of pigment and irregular swelling of the vessels, but no definite hæmorrhages. In the more acute cases, and particularly those associated with complete paralysis of the ocular muscles, total blindness usually followed.