Naphthalene-induced cataract model in rats: A comparative studybetween slit and retroillumination images, biochemical changes and naphthalenedose and duration.

PURPOSE. The purpose of the study was to comparedifferent methods of photographic evaluation of cataract formation in ratsin response to different regimes of naphthalene treatment. Furthermore, weintended to study the relationship between cataract extension and biochemicalparameters. METHODS. Brown Norway rats were treated with 0.10–1.5 g naphthalene/kgbody weight, twice a week for ten weeks to induce cataract or placebo. Slitillumination and retroillumination (SI and RI) photographs were produced byan EAS-1000 instrument to document cataract formation as light-scatteringintensity. The degree of the cataractous changes was quantified in SI photographsby the peak height and the integrated peak area, and in RI photographs bythreshold setting. Finally, the lens concentration of Na[sup +] and K[sup +] and the protein composition were analyzed and correlated to the photographicanalysis. RESULTS. The degree of the cataractous changes was most linearly relatedto dose and duration when the integrated peak area was estimated. However,protein fractions were non-linearly related to the cataractous changes estimated.Alterations in concentration of Na[sup +] and K[sup +] were smallor insignificant, which indicate that naphthalene-induced cataract is notcaused by osmotic changes. The lowest possible naphthalene dose to inducecataractous changes was between 0.10 and 0.50 g/kg twice a week for ten weeks. CONCLUSIONS. 0.50 and 1.0 g naphthalene/kg twice a week appeared to beoptimal, because the rats in these groups were healthy and the cataractouschanges were consistent between animals. Thus, the combination of the animalmodel with the cataract quantification system has the potential to be usefuland reliable in studies of cataract-preventive compounds. [ABSTRACT FROM AUTHOR]