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Zhaohua Yu, Nooshin TalebiZadeh, Martin Kronschlager, Per Söderberg; Thermally induced cataract is modulated by the biology of the lens. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2971.
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To determine if light scattering in infrared radiation (IRR) induced heat cataract is a pure instant aggregation of proteins or, in addition modulated by lens biology
Six-week-old albino Sprague-Dawley rats were used. The animal was anesthetized and the pupils were bilaterally dilated prior to laser exposure. Altogether, eighty animals were randomly divided into four groups of 20. All animals were unilaterally exposed for 30 s to 8.5 W 1090 nm infrared radiation with a spot size of 2 mm within the dilated pupil, irradiance 271 W/cm2. The beam was divergent on the cornea in order to generate a close to collimated beam between the lens and the retina to minimize retinal heating. During exposure, temperature was recorded both at the limbus and outside the sclera next to the optic nerve of the exposed eye. Depending on group belonging, the animals were sacrificed at 0.5, 4, 24, 168 h after laser exposure, respectively. Both lenses were extracted by a posterior approach for light scattering measurements and macroscopic photography in dark-field illumination.
The temperature increased rapidly. The temperature rise, expressed as a 95 % confidence interval for the mean was 30 s after exposure, 24 ± 4 °C at the limbus of the exposed eye and 16 ± 5 °C on the outside of the sclera next to the optic nerve of the exposed eye. The difference of light scattering in the lens, between exposed and contralateral not exposed lens, estimated as a 95 % confidence interval for the mean difference, was at 0.5, 4, 24, 168 h after exposure, 0.03 ± 0.05, 0.17 ± 0.06, 0.21 ± 0.09, 0.18 ± 0.09 tEDC, respectively, and lens opacity elevation was observed under dark-field illumination while the post-exposure time increased. The increase rate for light scattering was, estimated as a confidence interval, to 2.2±0.9 hrs, thus much longer than the laser exposure time.
An irradiance of 271 W/cm2 infrared radiation at 1090 nm projected in vivo on the cornea within the dilated pupil induces a temperature increase of about 24 °C in the anterior segment of the eye. Lens light scattering increases exponentially after the laser exposure. The light scattering increase rate is much longer than the temperature increase rate. Thus, the evolution of light scattrering is modulated by biology.
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