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A Banh, JG Sivak, MM Vijayan; Cold Cataract As A Function Of Age and Heat Shock Treatment In Bovine Lenses . Invest. Ophthalmol. Vis. Sci. 2002;43(13):467.
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Purpose: The precipitation of gamma crystallin in the lens is correlated with the formation of cold cataract and since there is a decrease in the amount of gamma crystallin with age, cold cataract is most apparent in young lenses. This research examines the optical effects of cold cataract as a function of age and heat shock treatment in cultured bovine lenses. Methods: A scanning laser instrument was used measure optical performance of 18 week old and 10 year old bovine lenses. The lenses of each age group were scanned initially at 37 degrees Celsius. One group, control lenses, were transferred into a modified glass culture cell and subjected to one cooling and warming cycle. The temperature cycle inside the cell started at 37 degrees then slowly cooled to 4 degrees and then warmed back up to 37 degrees. A group of heat shock lenses were subjected to an hour of heat stress at 42 degrees (5 degrees above incubation temperature). After being stabilized for 4 hours at 37 degrees, these lenses were also subjected to a cooling and warming cycle. Lens optical quality (relative lens transmittance) was measured periodically at different temperatures by measuring relative intensity (pixel excitation) of the refracted laser beam for each position as the laser scans across the lens. Results: The intensity of light transmittance is calculated as a percentage of refracted beam intensity compared to the calibrated intensity of a normal control lens before treatment. Control lenses from young eyes (n=6) show less loss of refracted beam intensity then lenses from older eyes (n=7) (26.6% vs 34.6% decrease in intensity). Cold cataract is most prominent in the heat shocked younger lenses (n=6, 80.7% loss in intensity) than in the old lenses (n=9, 74.9% drop in intensity). Also there is a significantly greater difference in change between the young control and heat shock groups then the difference between the two older groups (control and heat shock). Conclusion: Results from this study show an age effect on the cold cataract phenomenon in that young lenses are more affected by heat shock treatment and show more prominent cold cataract formation.
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