Biochemical changes in aphakia

Abstract

The distribution of ascorbic acid in the normal eyes of cows and rabbits and in the normal, partially aphakic and completely aphakic eyes of guinea-pigs has been studied. By using one eye of each animal as a control it was shown that there were significant decreases in ascorbic acid concentrations in the vitreous in complete aphakia but that normal levels were restored by the presence of lens tissue. The high ascorbic acid content of the retina was not altered by the absence of the lens. The lower levels of ascorbic acid found in aphakia were attributed not to any lack of ability of ascorbic acid to enter the aphakic eye but to the failure to maintain ascorbic acid in the more stable reduced form. The vitreous was completely liquid in aphakic but not in partially aphakic eyes; high dietary intakes of ascorbic acid did not alter the physical state of the vitreous. The copper-catalysed oxidation of ascorbic acid is inhibited by the presence of vitreous humour; this protective effect can be removed by treating the vitreous with p-chloromercuribenzoic acid. Hydroxyproline and ascorbic acid have been determined in the retinae of various species. These results have been discussed in relationship to pathological changes in the eye.