Regional enzyme profiles in rabbit lenses with early stages of naphthalene cataract

The naphthalene cataract in the pigmented rabbit, in contrast to the corresponding model in the pigmented rat, is characterized by a rather unstable cataract development during the later stages. Some animals rapidly develop mature cataracts, others develop cortical cataracts with almost no further progression inspite of a continued naphthalene treatment. To get more insight into this phenomenon, a study with pigmented rabbits (8 weeks old) was designed and at different stages of cataract development lenses were separated in single layers with the Bonn freeze-sectioning device. The key enzymes of the carbohydrate metabolism and the redox potential were determined in those layers. The results of the biochemistry failed however to explain the prominent differences of cataract development in-vivo. We conclude from these findings that the naphthalene cataract model in the pigmented rabbit shall no longer be used in drug side-effect or efficacy studies.