An attention to the effect of intravitreal injection on the controls of oxygen-induced retinopathy mouse model.

Oxygen-induced retinopathy (OIR) mouse model is widely used to study retinal neovascular diseases. Although the OIR procedure has been well established in detail, few studies to date have examined the effect of intravitreal injection using different-sized syringe needles at different time intervals after mouse pups returned to room air on this model. Initially, the significant reduction of NV and VO areas in the vehicle-controls of OIR drew our attention. We found that intravitreal injection performed using a 33 g-needle at 2 h after the pups returned to room air resulted in minimal NV and VO areas, causing a failure of OIR model. The results of ERG and OCT testing showed that 34 g-needle was more suitable than a 33 g-needle for intravitreal injection in the OIR model. We then investigated the effect of time interval after pups returned to room air on the OIR model. The results indicated that 8-24 h was a more suitable time for performing intravitreal injection. In conclusion, appropriate control of the effects of intravitreal injection on OIR requires attention to gauge of needle used, and the time interval after return of pups to room air.