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Frank Schaeffel, Ute Mathis, Focke Ziemssen; Effects of a human anti-VEGF antibody (Bevacizumab) on myopia development and choroidal thickness in the chicken. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5182. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Intravitreal injection of inhibitors of vascular epithelial growth factor (VEGF) represent currently the most promising treatment option for age related macular degeneration and myopic choroidal neovascularization. Bevacizumab has also been shown to affect the ERG, choroidal blood vessel leakage and turtuosity in rabbits. Sheng, Zhu and Wallman (ARVO 2012) found that VEGF isoform V165 can transiently thin the choroid in chicken in vitro. We have studied whether Bevacizumab can affect myopia development and choroidal thickness also in vivo.
24 chickens, 10 days old, were studied. After a single intravitreal injection containing either 625µg Bevacizumab, or vehicle alone, refractions and ocular dimensions were followed by infrared photoretinoscopy and A-scan ultrasonography, respectively, and daily OCT was performed to track choroidal thickness. Three experiments were done: (1) one eye Bevacizumab, the other vehicle, both covered with diffusers for 4 days (2) one eye Bevacizumab, the other vehicle, and both normal vision and (3) both eyes Bevacizumab, but only one eye covered with a diffuser for 4 days.
(1) A single injection of Bevacizumab reduced the amount of deprivation myopia (Bevacizumab -3.1+-2.7 D, vehicle -5.6+-2.7 D, p<0.02) and suppressed choroidal thickening that normally occurs when eyes recover from myopia on both sides (choroidal thickness in vehicle injected animals on the third day of recovery 925+-90 µm; in Bevacizumab treated eyes 294+-54 µm, and 377+- 64 µm in vehicle injected fellow eyes; p<0.001 in both cases) (2) Bevacizumab showed a trend of reducing choroidal thickness in animals with normal vision over a period of 8 days, relative to vehicle injected fellow eyes (3) However, binocular injections of Bevacizumab did NOT reduce choroidal thickness and myopia in a third experiment, compared to binocularly vehicle-injected animals.
In the first experiment, a single injection of Bevacizumab had long-lasting and powerful effects on choroidal thickening and myopia, even though Bevacizumab is an antibody raised against the human VEGF receptor. It remains unclear why the effect was weak or absent in the two other experimental paradigms. Potential causes might be species-specifity of the antibody or variable impact of local VEGF concentrations and isoforms, calling for more detailed studies in the future.
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