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T.K. Schlesinger, D.L. Hinton, M.S. Humayun; RPE Phagocytosis After 810 nm Laser Treatment . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1829.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the effect of 810 nm laser on retinal pigment epithelial (RPE) cell function. Introduction: Laser induced drusen reduction has been linked to decreased development of choroidal neovascular membranes and improved vision in people with dry age-related macular degeration. To investigate the cellular mechanism by which laser treatment induces drusen reduction, we are studying the effect of laser on the phagocytic function of explanted bovine RPE cell mononolayers. We also plan to investigate the effect of laser on RPE degradation of photoreceptor outer segment proteins, and on digestion of outer segment lipids. Our preliminary data indicate that the phagocytic function of RPE cells is unaltered by subclinical laser treatment, and is decreased by more intense laser treatment. Methods: Fresh bovine eyes were obtained, immersed in Hanks' balanced salt solution with 1% penicillin and streptomycin. The cornea, limbus, and scleral ring were removed followed by careful removal of the lens, vitreous, and neural retina, being careful not to disrupt the RPE. Sclera with intact choroid and RPE was then incubated with DMEM supplemented with 10% FBS. Confluent 810 nm laser was placed on the RPE using SLX Iridex micropulse diode laser (IRIS Medical). One explant was treated with laser intense enough to cause graying of the RPE, other explants were treated with decreased power or duration of laser. Explants were then incubated with 107 2µm diameter fluorescence labeled latex beads, (Molecular Probes, Eugene OR) for 36 hours. RPE was then dissected from the sclera and choroid, fixed in 2% paraformaldehyde, and analyzed with digital confocal microscopy to quantitate internalized beads. Results: The explant confluently burned to gray was used as the negative control, and the number of beads internalized by this monolayer was used as the background. Untreated RPE monolayers were analyzed and the number of beads internalized was used as the baseline (Phagocytic Index (PI) =1.0). RPE treated with half maximal power yielded a PI of 0.25. Half duration PI=0.35, One quarter power PI=0.60, One eighth duration PI=0.60, one sixteenth duration PI=0.95. Conclusion: The phagocytic function of RPE cells can be diminished by progressively increasing intensity of 810 nm laser treatment.
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