Abstract
The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED50 thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED50 thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED50 thresholds were correlated by a power law equation, ED50 = 6.31t0.66 [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED50 thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards.
Highlights
The transitional infrared wavelength range refers to the wavelength band from 1.3 μm to 1.4 μm [1,2,3]
One interesting phenomena was that for the 10 s exposure duration, the dilated pupil retracted seriously after two or three exposures at all of the four laser doses (24.0, 30.0, 38.1, and 47.1 J), which prevented the delivery of more exposures to the retina
The rabbit retinal ED50 thresholds given in terms of the total intraocular energy (TIE) for 1319 nm at exposure durations of 0.1 s, 1 s and 10 s were 1.36, 6.33 and 28.6 J respectively
Summary
The transitional infrared wavelength range refers to the wavelength band from 1.3 μm to 1.4 μm [1,2,3]. With the wavelength increase in this region, the most sensitive tissue changes gradually from the retina to the cornea. Damage may be induced in one or more of the cornea, lens, and retina/choroid, depending on the precise exposure parameters [1,2,3,6,7]. Thresholdlevel damage occurs at the retina for relatively large corneal beam spot while occurs at the cornea for relatively small spot [3]. Retinal or corneal threshold lesion involves full thickness of that layer [8,9]. These characteristics are remarkably different from the ocular damage induced by other wavelength range and receive increasing concern
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