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Hussam El Chehab, Alexis Bemelmans, Céline Nouvel-Jaillard, Marie-Laure Niepon, Jean-Paul G Renard; POFAL Study: «Protection Oculaire Face aux Agressions Lasers», Phase I. Invest. Ophthalmol. Vis. Sci. 2014;55(13):6369.
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© ARVO (1962-2015); The Authors (2016-present)
Risk of laser beam exposure, particularly to lasers "pointers" easily available on open sale or on internet increases every year. Many incidents and accidents have been reported over the last 3 years in France. Side effects from these exposures vary, glare is systematic with a visual disability. Purpose of this study is to try to determine a retinal lesion threshold secondary to such exposures.
A laser emitting at 532nm with a power and duration control system of beam has been developed specifically for this study to achieve the different exposure. A first phase is performed in pigmented rodents to clarify lesion and scar phenomena with different combinations of time-power beam exposure. Powers ranged between 0 to 4.5mW (corresponding to class II and IIIa lasers) and durations between 0 and 0.35 seconds (around mean time of blink reflex =0.25sec). A second phase is performed in non-human primates (NPH) with blink reflex time and powers retained during first phase. Histological analysis of all retinal layers after paraffin embedding and staining was performed to each phase. These analyzes were performed in foveal zone, perifoveal and 10° superior, inferior, nasal and temporal to macula. Several immunoassay analyzes were performed to assess apoptosis and cellular damage (TUNEL, GFAP). This research was conducted in compliance with ARVO statement for the use of animals in ophthalmic and visual research.
A significant linear correlation between energy (power*time) and photoreceptor thickness is found in rodents (r=-0.16, p<0.001). Immunoassay confirm apoptosis and cellular damage of outer layers. Photoreceptors alterations are located only in foveal zone in NHP. Outer layers thickness is statistically lower when exposure power is greater than 1mW. A significant correlation between energy and photoreceptor thickness is also found only in foveal zone (r=-0.51, p=0.01). Immunoassay for apoptosis is also positive in foveal zone when power exposure was greater than 1mW.
This study reports systematic tissue damage when power exposure correspond to upper limits of class II lasers (1mW). This is the first in-vivo study analyzing effects of low power laser beam exposure easily available. It provides an anatomical substrate for functional impairment reported in a growing number of incidents and accidents. These initial results are used to guide and adapt research on protection systems for people exposed.
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