This chapter discusses the cases of postoperative blindness reported in the literature and the theories that attempt to explain the mechanisms involved. Although uncommon, alterations in vision and blindness after anesthesia for major surgical procedures, particularly cardiopulmonary bypass or spine surgery, are well documented, with an incidence varying between 0.05% and 1%. Accurate incidence data are unavailable because it is not known what percentages are reported. However, the large number of case reports over many years has provided some significant information. Although sustained compression of the eye is an important cause, postoperative visual loss may also occur, in an unrelated manner, because of ischemic optic neuropathy, central retinal artery or vein occlusion, or cortical blindness.
The biological relevance of Fe(II)/Fe(III) is becoming evermore apparent, especially in relation to its potential role in the progression of neurodegenerative diseases such as Parkinson's and Alzheimer's disease. The reported relationship between smoking and a reduced incidence of neurodegenerative disorders prompted this work. In order to investigate whether nicotine can interact with iron, we have studied the electrochemical behaviour of a Fe(II)/Fe(III) redox couple in the presence of nicotine. Solubility issues and lack of available nonreacting salts of nicotine necessitated studies being conducted at low pH values. Cyclic voltammetry experiments revealed a definite alteration in the electrochemical behaviour of the Fe(II)/Fe(III) redox couple suggesting the capability of nicotine to complex with free iron and, hence, reduce its reactivity. This is evident from a slower rate of heterogeneous electron transfer, ks, and a shift from reversible to quasi-reversible behaviour, as characterised from the diffusion coefficient (D), the full width half maximum (FWHM), DeltaEp and Ef. Additional complexation titrations, pH ranging from 1 to 7, confirm a weak complexation reaction occurring between Fe(III) and nicotine.
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