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Twenty male albino rabbits were studied. Four animals served as controls; the remaining 16 animals represented the treated group. All the treated animals were exposed to the same amount of energy delivered by the excimer laser (pulse rate: 20 Hz, fluence 250mJ/cm2; number of pulses: 6032; cumulative UV dose 1508 J/cm2) and were divided into eight groups of 2 animals each (four eyes). Samples of aqueous humor and lens were obtained at the following intervals: 5, 10, 20 and 40 min and 1, 2, 3 and 4 weeks after photorefractive keratectomy (PRK). The levels of reduced and oxidized glutathione, hydrogen peroxide, ascorbic acid and malondialdehyde were determined. Aqueous humor analyses, twenty min after PRK, showed no significant differences with pre-treatment values, while the observed variations in lens were constantly present over the entire follow-up period (one month). These findings suggest that the biochemical lens alterations induced by PRK may represent the earliest events relevant to cataractogenesis in the rabbit.

It was evaluated whether ArF 193 nm excimer laser corneal surgery represents a risk factor in cataractogenesis. For this purpose, 20 male albino rabbits underwent a photorefractive keratectomy and biochemical analyses on aqueous humour (hydrogen peroxide, ascorbic acid, and reduced and oxidized glutathione) and on lens (malondialdehyde, reduced and oxidized glutathione) were performed. In the aqueous humour of all treated animals a significant increase in hydrogen peroxide and in oxidized glutathione and a concomitant decrease in ascorbic acid and reduced glutathione concentration were observed. Moreover, all these variations were significantly correlated with the cumulative UV dose used. In the lens, after excimer laser corneal surgery, there was a dramatic loss of reduced glutathione and a parallel increase in oxidized glutathione levels. Malondialdehyde concentration was also increased, but only at the highest UV exposure. Moreover, all these variations were significantly correlated with the cumulative UV dose used. These findings demonstrate that the exposure of aqueous humour and lens to the secondary radiation generated after ArF 193 nm excimer laser corneal photoablative keratectomy induces biochemical modifications which are known to be markers of cataractogenesis.

The activity of galactokinase in red blood cells of 30 patients affected by idiophatic presenile and senile cataract, and of 20 age-matched controls with perfectly transparent lenses, was investigated. The results obtained show a partial deficiency of the galactokinase activity in the patients affected by presenile idiopathic cataract. There is, moreover, a significant relationship between the cortical form of cataract and enzymatic reduction.

The activity of galactokinase in red blood cells, has been assayed in 17 patients with idiopathic senile and presenile cataract and in 12 age-matched subjects with perfectly transparent lenses. 3 of the idiopathic cataract patients (17.6%) showed low erythrocytes GK activity, while nobody in the control group showed reduced GK activity. Although preliminary, our results seem to support the possibility that a chronic disorder of galactose metabolism may be involved in the pathogenesis of the idiopathic senile and presenile cataract.