Objective: Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a new examination method which enabled the measurement of fluorescence lifetime (FLT) of the human fundus. We investigated changes in the FLT of the autofluorescence of retinal pigment epithelium (RPE) in organ culture under oxidative stress.
Materials and methods: Ex-vivo porcine RPE was cultured with hydrogen peroxide (H₂O₂) at concentrations of 0, 1.5, and 3 mM and FLIO［excitation wave length: 473 nm, detection range: 498-560 nm (Channel 1) and 560-720 nm (Channel 2) ］was conducted after 24h and 48h. Cell viability and intracellular reactive oxygen species (ROS) were examined using calcein-AM and 2', 7'-dichlorofluorescein diacetate, respectively.
Results: At all H₂O₂ concentrations, there was no significant decrease of rate of viable RPE cells within 48h. The amount of intracellular ROS showed no significant change after 24h at any H₂O₂ concentration, whereas a concentration-dependent increase was observed after 48h. In FLIO, H₂O₂ concentration-dependent and exposure time-dependent increase of the FLT (τ) and the decrease of the component ratio of short-long FLT (a₁/a₂) were observed, which was more apparent in the short wavelength channel (Channel 1).
Conclusions: It has been suggested that FLIO may noninvasively detect the RPE under oxidative stress. The direct influence of H₂O₂ was thought to be more sensitively detected in the short wavelength channel. Further study is necessary for the better understanding of the clinical application of FLIO.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 123: 105-114, 2019.