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P. G. Soderberg, R. Al-Saqry, K. Schulmeister, K. Galichanin, M. Kronschläger, Y. Zhaohua; Evolution of Near-infrared Radiation Induced Cataract. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2130.
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© ARVO (1962-2015); The Authors (2016-present)
To elucidate the evolution of infrared radiation cataract.
Six weeks old albino Sprague-Dawley rats were the experimental animals. All animals were anesthetized with ketamine/xylazine, 95/14 mg/kg body weight, 20 min prior to exposure and the pupils of both eyes were dilated with tropicamide 10 mg/ml. In the first experiment, 12 animals were divided into four exposure time groups of three animals, 25, 64, 169 and 400 s. In each animal, one of the eyes was exposed to a 3 mm in diameter spot, with quasi top hat spatial distribution of 6.2 W, 1090 nm generated with a CW fiber laser (Model SP-120C, SPI Lasers, UK). The animals were sacrificed 24 hrs after exposure and the lenses were isolated for macroscopic imaging in dark-field illumination and measurement of intensity of forward light scattering. In the second experiment, the same power of the laser, 6.2 W, and the same exposure condition, was used but with the exposure time set to 8 s. Altogether, 16 animals were exposed unilaterally and then sacrificed at 6, 18, 55 or 168 hrs after the exposure. The lenses were then isolated for macroscopic imaging in dark-field illumination and measurement of intensity of forward light scattering.
In the first experiment, if was found that the difference of intensity of light scattering induced between the exposed and the contralateral eye increased as a function of exposure time and that the increase can be approximated with a 2nd order polynomial without 0 and first order term, CIk(0.95) = 0.18 ± 0.0004 rel. units/s (d.f. 11). Exposure times above 8 s induced a signal just above noise. In the second experiment, it was found that the light scattering induced increases exponentially declining as a function of time after exposure (1/k=75 hrs).
In vivo exposure to near infrared radiation that induces just above detectable light scattering in the lens is associated with a delayed onset of light scattering. This finding indicates that there may be a photochemical effect of infrared radiation and thus a cumulative effect of sub threshold exposures to e.g. LEDs in remote controls and sensing devices.
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