Portal de Periódicos da CAPES

Siderosis Bulbi

1954; BMJ; Volume: 38; Issue: 12 Linguagem: Inglês

10.1136/bjo.38.12.727

1468-2079

J. F. Ballantyne,

Traumatic Ocular and Foreign Body Injuries

SIDERosIs bulbi is a pigmentary and degenerative change in the eye that follows the intra-ocular retention of a foreign body containing iron.The pathological anatomy of siderosis was first reported by von Hippel (1894), who distinguished two types of siderosis: haematogenous, in which the iron was derived from the blood, and exogenous, in which it came from an intra- ocular foreign body.This paper will deal with the latter, discussing corrosion of iron, its diffusion and precipitation throughout the eye, the pathological changes, and the clinical picture.Corrosion of Iron.-Corrosion is the destruction of a metal resulting from its contact with a liquid.Factors which increase the velocity of corrosion are the presence of oxidizing agents, uneven surfaces of the metal, agitation of the liquid, higher temperature, and greater alkalinity.The human eye offers an optimal situation for corrosion.Diffusion and Precipitation of Lron.-The chemical processes in ocular siderosis have been debated for years.Von Graefe (1860) thought that the iron diffuses through the eye in the form of oxides.Leber (1882) felt that a solution of iron bicarbonate is formed, which then is oxidized and precipitated in the ocular tissues.The theory of Mayou (1925Mayou ( , 1926) ) was that iron is in the form of colloidal ferric hydroxide, which is positively charged.Bunge (1891) considered that the iron is dissolved by carbonic acid, circulated as a soluble carbonate being deposited in an insoluble form by the action of acid salts.Friedenwald (1954) believes that the staining of tissues by iron is due to ferric ions in low concentration which combine with sulph-hydryl groups in the cells.Particles of oxidized iron tend to precipitate in ectodermal cells.Many theories have been advanced to explain this fact.Mayou (1925Mayou ( , 1926) ) feels that the activity of epithelial cells renders them negatively charged.The negative charge attracts the positively charged colloidal particles.Wolff (1951) did not ascribe to certain tissues a special affinity for iron, but thought that all living cells took up iron more readily than the connective tissue, and that connective tissue took up more iron that the glass-like membranes.Pathology.-Theepithelium of the ciliary body is the first tissue affected and the non-pigmented epithelium stains earlier.The iris is affected most at the anterior limiting layer and in the sphincter and dilator muscles.Macro-