Ocular melanosis with special reference to chlorpromazine.

Causes of Melanosis other than Chlorpromazine THE pathological deposition of melanin is rarely seen in the tissues of the eye. Normally, small collections of melanin are sometimes seen in the eyes of Caucasians where the ciliary vessels pierce the sclera near the limbus. Larger collections of melanocytes form a benign naevus which may invade the cornea, or there may be multiple collections of melanocytes scattered throughout the conjunctiva forming the condition termed by Reese (1951) "precancerous melanosis". Melanin deposits around the limbus can also be seen in Addison's disease. Deposits of melanin derived from the iris and ciliary body and transmitted by convection currents in the anterior and posterior chambers are commonly seen on the endothelial surface of the cornea in old age, in cases of diabetes, and after eye operations. Here they adhere to the lower part of the corneal endothelium, usually in a characteristic shape (Krukenberg's spindle). Brown lines on the lower corneal surface, which would appear to be due to melanin but which are in fact due to haemosiderin, are found in many normal middle-aged and elderly persons (Hudson-Staihli line). They are also noticed in association with corneal scars and at the head of pterygia. Similar brownish-olive lines in the lower half of the cornea have been described as a toxic manifestation of chloroquine therapy (Smith, 1962); it is not known if this is related to melanin deposition. In an autopsy case, it was reported that the basal layer of the corneal epithelium was hyperplastic and contained leptochromatic nuclei with a prominent basal membrane, but melanocytes were not mentioned (Lloyd and Hiltz, 1965). A brown olive-green deposit of copper in the deeper corneal layers, resembling an arcus senilis, is seen in hepato-lenticular degeneration (Wilson's disease) and following the retention of copper fragments in the eye after injury, e.g. from an exploding percussion cap (Kayser-Fleischer ring). In-both these conditions the copper may also be deposited on the anterior capsule of the lens behind the pupil where it forms a 3-4 mm. central green opacity with radiating arms resembling a flower. Such an opacity is commonly described as a sunflower cataract, but, while it may resemble a sunflower, it is not strictly a cataract. A similar-shaped deposit of melanin in the anterior capsule and cortex of the lens will be presently described as an early manifestation of chlorpromazine toxicity. Here, however, the corneal deposits do not resemble the Kayser-Fleischer ring or the pigmentation produced by chloroquine toxicity, but consist of granules of melanin scattered diffusely through the cornea and closely associated with Descemet's membrane.