Abstract
Purpose: :
In the last decade it has been proven that visible short wave light can trigger retinal degeneration. It could be shown also in retinal ganglion cell cultures that intensive white light (with blue component) is harmful. In order to specify frequencies and intensities we irradiated retinal ganglion cells with different blue light sources in order to determine the damage quantitatively.
Methods: :
R28 cells were incubated under three different light irradiations (405 nm (0.6 W/m2), 405 nm (1.5 W/m2), 405 nm (4.5 W/m2), or 470 nm (4.5 W/m2)) during 6h or 24h. Apoptotic changes were determined by flow cytometry on cells incubated with the following dyes: sub-G1 assay, annexin V binding, and YO-PRO (membrane permeability assay). These dyes were used as apoptosis parameters. Furthermore reactive oxygen species intermediate production and the resazurin metabolism assay (RMA) were used as mitochondrial function parameters.
Results: :
Damage showed by the RMA after 6h or 24h of irradiation is directly proportional to the intensity of the 405 nm light. After 24 h of 405 nm (4.5 W/m2) treatment sub-G1 assay, annexin binding, and membrane permeability for propidium iodide were significantly increased compared to control. At 470 nm no significant changes were was detectable.
Conclusions: :
The rate of damage caused by blue light is directly proportional to the intensity and inversely proportional to the wavelength.
Keywords: ganglion cells • degenerations/dystrophies • flow cytometry