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Jan Tode, Elisabeth Richert, Alexa Karina Klettner, Ralf Brinkmann, Stefan Koinzer, Johann Roider; Laser Thermal Stimulation of the Retina (TS-R) reduces Thickness of Bruch’s Membrane (BrM) in Apolipoprotein (Apo) E knock out Mice. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4424.
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© ARVO (1962-2015); The Authors (2016-present)
An increase in BrM thickness is one of the main features of non exsudative age related macular degeneration (dry AMD). Currently there is no adequate treatment for dry AMD. We investigate the effect of TS-R in an AMD mouse model.
Ten eyes of five 4 month old ApoE knock out mice (B6.129P2-Apoetm1Unc/J) were used. We treated 5 eyes of 5 ApoE knock out mice with a TS-R laser (laser parameters: 532 nm wavelength, continuous wave, 50 µm spotsize, 10 ms duration, mean power 5.4 mW) and used the fellow eye as control. We applied 70 to 100 laser spots distributed uniformly with a spacing of 2 spots. Power was chosen 70 % below clinical visibility.Eyes were examined by ophthalmoscopy, optical coherence tomography (OCT) and fluorescein angiography (FLA) at the day of treatment, 1 day and 1 month after treatment. We enucleated the eyes after 1 month and analyzed BrM thickness by transmission electron microscopy (TEM) in a blinded standardized manner.
Fundus images revealed that all ApoE knock out mice had AMD associated alterations like drusen and areas of hypopigmented retinal pigment epithelium (RPE). Drusen were also visible in OCT. FLA did not reveal any pathological findings.Subthreshold TS-R laser spots were not visible by fundus imaging, OCT and FLA, 2 hours, 1 day or 1 month after laser treatment.There was no significant change in the number of drusen of the treated eye before TS-R (mean 4, +/- 4) compared to the treated eye after TS-R (mean 7, +/- 3) and compared to the control eyes (mean 5, +/- 2).However, TEM revealed a significant reduction (p< 0.001) of BrM thickness in laser treated eyes (mean 524.8 nm, SEM 11.4 nm) compared to their fellow control eyes (mean 585.7 nm, SEM 12.9 nm). BrM of all treated eyes was thinner than BrM of their fellow control eyes.
Laser thermal stimulation of the retina TS-R reduces BrM thickness in ApoE knock out mice without damage to the retina. It may be a treatment option for dry AMD.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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