The Origin of Cataracts in the Lens from Infrared Laser Radiation.
DUKE UNIV MEDICAL CENTER DURHAM NC
Pagination or Media Count:
The cataracts resulting from IRinfrared radiation exposure are compared with those linked to UVultraviolet exposure. The IR exposure produces changes in the lens proteins, the crystallins, while UV exposure seems to attack specific amino acids. Gel electrophoresis of lens proteins have been used to detect the earliest changes possible in cataract formation following exposure to IR from broad band and laser source irradiation. Cataracts can be easily formed in rabbit lenses in vivo when the laser radiation is restricted to the lens allone at power levels above 1 W for 1 minute. Lower power levels do not produce immediate cataracts but changes in lens proteins can be detected by thin layer isoelectric electrophoresis of plain polyacrylamide gels and with sodium dodecyl sulfate SDS or 6 M urea. The plain gels pH 3.5 to 10 showed a decrease in the alpha crystallins indicating a possible change of soluble alpha crystallin to an insoluble high molecular HM weight form. However, small amounts of beta and gamma crystallins may also be involved in the formation of a HM insoluble aggregate. Soluble HM weight crystallins often were detected as the alpha crystallin disappeared. This HM soluble fraction may be an intermediate step in the rocess in forming insoluble alpha crystallin. Following higher laser power levels the beta crystallin has a markedly decreased mobility which also might be a precursor for the insolubilization of all crystallins. These changes are compared with similar changes in the lens proteins which follow broadband IR exposure in vivo, or in vitro, or in lenses incubated in vivo at various temperatures which showed some, but not all, of the same changes.