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C. Cejka, V. Guryca, J. Sirc, J. Michalek, J. Platenik, J. Cejkova; Hydrated Cornea After UVB Irradiation Absorbs More Light Across the Whole Spectrum of UV and VIS Than Does the Normal Cornea . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2991.
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Previous studies clearly showed that repeated exposure of the cornea to UVB rays generated reactive oxygen species led to the great decrease of corneal antioxidants (such as ascorbic acid, superoxide dismutase, glutathione peroxidase), which might highly contribute to the danger from oxidative damage to the deeper parts of the eye. Purpose of this study was to examine the light absorption properties of the UVB–irradiated cornea in which natural antioxidants were overhelmed.
Adult New Zealand white rabbits were employed. The corneas were irradiated with UVB (once a day during 5 days, a dose per day 1.01 J/cm2). Afterwards the rabbits were left without any treatment and on day 8 they were sacrificed. Absorbances of corneal centres (a circle of 6 mm diameter) of normal corneas (as controls) and irradiated corneas were measured over a range of 190–650 nm using a scanning spectrophotometer (HeliosSb 84021).
Repeatedly irradiated corneas with UVB became hydrated and the corneas with increased hydration absorbed more light across the UV (particularly UVB) and VIS spectrum than did the normal corneas. The cause of this effect was not only the increase in corneal thickness but also the changes in chemical properties of hydrated corneas. This was apparent from theoretical analysis of the measurements.
Even if increased corneal hydration is generally taken as a pathological event, from the view point of UV radiation it is an efficient natural mechanism for protecting of the deeper parts of the eye against further UV penetration (particularly UVB) and reactive oxygen species generated by them.
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