Abstract
Abstract: :
Purpose: The surfactant sodium dodecyl sulfate (SDS), which is used in many commercial solutions, induced a significant decrease in lens optical function compared to controls (Sivak et al., 1997). This study was undertaken to investigate the possible mechanisms of chemical-related toxicity of the bovine lense in vitro using SDS as a chemical model. Methods: Bovine lenses were exposed to SDS (0.1-0.00625%) for 30 minutes, washed with saline and incubated in culture medium at 370C and 4-5% CO2. Lens optical function was analysed using the ScantoxTM In Vitro Lens Assay System (Harvard Apparatus, Holliston, MA) before exposure, immediately, 4, 8 and 24 hours after the exposure. After 24 hours mitochondrial electron transport chain potential (Δ; ψ m) in epithelial and superficial cortical lens fibre cells of the same lenses were analysed using confocal microscopy and 20 µ M rhodamine 123. Results: Compared to controls (n=18) loss of sharp focus (as measured by the variability of back vertex distance) was evident immediately following exposure to 0.1% SDS (n=14, p<0.05) increasing from 0.42±0.05 mm (SEM) initially, to 0.85±0.16 mm (SEM). At 24 hours loss of sharp focus became evident in the 0.025% SDS group (n=16, p<0.05) and the 0.0125% SDS group (n=11, p<0.05) increasing from 0.39±0.03 mm (SEM) initially, to 0.75±0.1 and 0.36±0.03 mm (SEM) initially, to 0.92±0.09 mm (SEM), respectively. At 24 hours sharp focus did not decrease significantly from controls in 0.05% SDS (n=15, p=0.09) and 0.0625% SDS (n=11, p=0.99) group lenses. Confocal analysis after 24 hours showed a SDS concentration-dependent decrease of the Δ; ψ m of epithelial and superficial cortical fibre cells. A recovery of the Δ; ψ m of epithelial and anterior superficial cortical fibre cells but not posterior superficial cortical fibre cells, could be seen with 0.0625% SDS. Conclusion: The results of this study indicate that lens optical function and the mitochondrial activity of epithelial and superficial cortical fibre cells are a sensitive in vitro model of ocular chemical toxicity. A recovery of the Δ; ψ m of epithelial and anterior superficial cortical but not posterior superficial cortical fibre cells at 0.0625% SDS, may suggest that the mitochondrial integrity of the posterior superficial cortical fibre cells is most sensitive to chemical damage. The results further suggest that recovery of lens metabolic function maybe necessary for the recovery of lens optical properties.
Keywords: 494 ocular irritancy/toxicity testing • 500 optical properties • 475 mitochondria