Effect of Estimated Individual Vitreous Volume on Intraocular Pressure Spikes After Intravitreal Anti-Vascular Endothelial Growth Factors Injection.

Introduction: The present study aimed to evaluate the effect of estimated individual vitreous volume on intraocular pressure (IOP) spikes after intravitreal anti-vascular endothelial growth factor (VEGF) injections (IVI).

Methods: Vitreous volumes (VV) of eyes were calculated using an axial length (AL) based formula AL3 x (π/6) x 0.76+0.012 x (AL-24) and study eyes divided into four groups according to their VV; <4.5 cm3 (Group 1, n=52), 4.5-5.0 cm3 (Group 2, n=60), 5.0-5.50 cm3 (Group 3, n=60), and >5.50 cm3 (Group 4, n=35). IOP measurements were taken at pre-intravitreal injection (IVI), immediately after (Post-IVI-0), 5 minutes (Post-IVI-5), 15 minutes (Post-IVI-15), and 30 minutes after the IVI.

Results: A significant IOP change was found between the five time points in all groups (p<0.001 for all). Regarding the same time point measurement comparison between the groups, only a statistically significant change was found in the Post-IVI-0 point (p=0.001). In posthoc analysis, Group 1, Group 2, and Group 3 had significantly higher IOP values when compared to Group 4 (p<0.05 for all). Patients treated with prefilled Ranibizumab syringes exhibited lower IOP increases than vial-prepared Aflibercept injection at the post-IVI-0 time point (p=0.042).

Conclusions: A similar increase in IOP was observed in eyes with low and intermediate volumes, but the increase was less pronounced in those with high volumes after the IVI. PFS form showed a lower IOP increase tendency in comparison with vial-prepared forms of the molecules.