Purchase this article with an account.
Zhaohua Yu, Karl Schulmeister, Nooshin Talebizadeh, Martin Kronschläger, per söderberg; Near infrared radiation induces cataract thermally. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5750.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
1) To estimate the just above threshold exposure time for the near IRR exposures in the seconds time domain at a constant irradiance of 197 W/cm2 within the pupil, and the time evolution of lens damage after the estimated threshold exposure. 2) To determine the temperature time evolution in the eye during an 8 s in vivo threshold exposure to 197 W/cm2 at 1090 nm, and the heat diffusion associated with exposure. 3) To investigate if 1090 nm IRR induces cataract photochemically considering irradiance exposure time reciprocity.
The 6-weeks-old albino rats were anesthetized with ketamine 95 mg/kg plus xylazine 14 mg/kg intraperitoneally, ten minutes before exposure. The pupils of both eyes were dilated with tropicamide, 5 mg/ml. Five minutes after pupil dilation, the animals were unilaterally exposed to 1090 nm IRR within the pupil area. Temperature was recorded with thermocouples placed in the selected positions of the eye. At the planned post-exposure time, the animal was sacrificed and the lenses were extracted for measurements of forward light scattering and macroscopic imaging.
The in vivo exposure to 197 W/cm2 1090 nm IRR required a minimum 8 s for cataract induction. There was approx 16 h delay between exposure and light scattering development in the lens. The same radiant exposure was found to cause a temperature increase of 10 °C at the limbus and 26 °C close to the retina. The rate constants estimated for the increase of temperature induced by the exposure was on the order of 10 times higher than that estimated for decrease of temperature after the end of exposure. The in vivo exposure to 96 W/cm2 1090 nm IRR with exposure time up to 1 h resulted in an average temperature elevation of 7 °C at the limbus with the cornea humidified and no significant light scattering was induced one week after exposure.
An in vivo exposure to 197 W/cm2 IRR at 1090 nm within the pupil for 8 s induces cataract with a time delay. This threshold exposure for cataract induction causes a temperature rise of 10 °C at the anterior segment of the rat eye. IRR at 1090 nm produces thermal cataract, probably by indirect heat conduction from absorption in tissues surrounding the lens. There is no cataract development given that the limbal temperature increase is below 8 0C.
This PDF is available to Subscribers Only