Copper concentration in cornea, iris, normal, and cataractous lenses and intraocular fluids of vertebrates

A method using electrothermal atomic absorption spectroscopy was developed for the determination of copper (Cu) concentration in the cornea, iris, and lens of a variety of species, including dog, cat, rabbit, horse, and toad. Previously described methods were used to determine Cu in aqueous and vitreous humor. There was little difference between copper levels in the same tissue or fluid across the species. However, there were age and pathology-related changes in Cu concentration of the aqueous humor, cornea, and lens. In the groups of older dogs, the Cu concentration of the aqueous humor and cornea is significantly lower than the two younger groups. In both the dog and rabbit, lenses from young animals have the lowest copper concentration which increases and then finally decreases with age. Canine hypermature cataracts have a significantly higher copper concentration than control dogs of all age groups. There was no correlation between Cu concentration in the intraocular fluids and the cataractous lenses taken from the same eye. The role such an increase in lenticular Cu concentration may play in cataractogenesis needs to be explored.