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In vivo high power infrared radiation exposure time dependence of lens light scattering
Author(s) -
ALSAQRY R,
GALICHANIN K,
LI Y,
SÖDERBERG PG,
SCHULMEISTER K,
HUSINSKI J,
BUCHT C
Publication year - 2008
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2008.5444.x
Subject(s) - optics , laser , radiation , lens (geology) , materials science , xylazine , scattering , ophthalmology , medicine , ketamine , physics , anesthesia
Purpose To determine the exposure time dependence of lens light scattering after high power in vivo infrared radiation exposure of the eye. Methods The experimental animal was 6 weeks old albino SD rat. Altogether, 12 animals were divided into four exposure time groups (5, 8, 13, 20 s). The animals were anesthetized with ketamine‐xylazine, 95/14 mg/kg bodyweight, 20 min prior to exposure and both eyes were dilated with tropicamide 10 mg/ml. The infrared radiation source was a single mode CW fiber laser emitting at 1090 nm (Model SP‐120C, SPI Lasers, UK) with the output power set to 6.2 W. The primary laser beam was focused just in front of the anterior focal point of the eye with an F# close to that of the rat eye so that a divergent beam entered the eye with a spot size of 3 mm in diameter inside the dilated pupil. This allowed for a homogenous intensity distribution within the lens and a large spot size on the retina. One week after exposure, the animal was sacrificed and the lenses were extracted for darkfield macroscopic imaging and measurement of intensity of forward light scattering. Results The intensity of forward light scattering increased with increasing exposure time. The increase was well described by a 2nd order polynomial, omitting the 0:th and the first order term. The threshold exposure time, estimated as Maximum Tolerable exposure Time (MTT:2.3:16) was 4.8 s. Considering the power used, this corresponds to 30 J, thus delivered over 3 mm diameter which implies a radiant exposure of 4.2 MJ/m2. Conclusion At 1 week after exposure to 6.2 W of 1090 nm, the intensity of forward light scattering in the lens increases with increasing exposure time and the threshold exposure time is 4.8 s.