To examine retinal nerve fiber layer (RNFL) changes after intravitreal injection of bevacizumab in patients with or without underlying glaucoma.

A total of 104 eyes of 104 patients with retinal disease undergoing intravitreal injection of bevacizumab were prospectively investigated. Bevacizumab injections (1.25/0.05 mg/mL) were performed using a standardized technique. In the patient who had pretreatment with intraocular pressure (IOP)-lowering medication, 1 drop of brimonidine was instilled 30 minutes before the injection. Before and after the intravitreal injections, the patients were monitored for IOP and evaluated with optical coherence tomography using Stratus at least 3 months after the injection.

Thirty minutes after injection, 6.4% of patients had an IOP over 30 mm Hg in the non-pretreatment group while no patient had an IOP over 30 mm Hg in the pretreatment group. In eyes with only retinal diseases, the RNFL thickness did not change significantly after the injection regardless of pretreatment, whereas in eyes with underlying glaucomatous damage and no pretreatment, significant decrease in RNFL thickness was observed at the superior ( p = 0.036) and temporal ( p = 0.048) sectors of the optic nerve head without pretreatment.

Intravitreal injection of bevacizumab did not typically cause significant changes in RNFL thickness; however, in eyes with underlying glaucoma without pretreatment, a significant decrease in RNFL thickness was observed in the superior and temporal sectors of the optic nerve head. Therefore, applying IOP-lowering pretreatment medication before intravitreal injection of bevacizumab is required for protection of RNFL in glaucoma patients.