Acute and chronic optic nerve head biomechanics and intraocular pressure changes in patients receiving multiple intravitreal injections of anti-VEGF

Purpose To evaluate acute and chronic changes in optic nerve head (ONH) structures and intraocular pressure (IOP) in patients receiving intravitreal injections (IVIs) of anti-VEGF. Methods Twenty-nine eyes receiving IVIs for the first time were studied. IOP, retinal nerve fiber layer (RNFL) thickness, and ONH structures were evaluated by Spectralis optical coherence tomography with enhanced depth imaging technology. Structures were measured before and 5 min after each one of the three monthly injections of a loading dose treatment. In 13 eyes (44.8%) with more than six IVIs, another evaluation pre and immediately postinjection was performed after 1 year. Results A significant acute and transient IOP increase (all p <= 0.001), Bruch's membrane opening (BMO) enlargement (p <= 0.001), cup widening (p < 0.05) and deepening (p <= 0.001), and prelaminar tissue thinning (p <= 0.001) were observed 5 min after each injection. Compared with baseline values, a significant BMO expansion (p = 0.001) and RNFL thinning (p < 0.001) were observed in the third month. In eyes with more than six IVIs, similar immediate postinjection changes, including IOP increase (p = 0.001), prelaminar tissue thinning (p = 0.007), and cup deepening (p = 0.012) were observed at 1 year, while BMO expansion was not significant (p = 0.556). Compared with baseline preinjection values, a significant BMO expansion (p = 0.003), prelaminar tissue thinning (p = 0.011), and cup deepening (p = 0.006) in the inferior region of the ONH occurred. No change in IOP was observed at the end of follow-up. Conclusions Repeated IVIs could lead to irreversible changes in ONH structures. Large-scale, prospective studies are required to determine the long-term effects of anti-VEGF treatments in ONH tissues.