Immediate and Short-Term Intraocular Pressure Changes Following Intravitreal Injection and Associated Factors

Objectives: To evaluate the immediate and short-term changes in intraocular pressure (IOP) following intravitreal injection (IVI) of anti-vascular endothelial growth factor (VEGF) agents and to identify the clinical and procedural factors associated with IOP elevation after treatment. Methods: This retrospective study included 118 eyes from 115 patients who underwent IVI with anti-VEGF agents at Osaka Metropolitan University Hospital between September 2024 and January 2025. IOP was measured at three time points, namely before injection, within 1 min after injection, and at 30 min, in selected eyes with a post-injection IOP ≥ 25 mmHg. Differences in IOP elevation were analyzed according to the disease type and anti-VEGF agent. Univariate and multivariate linear regression analyses were performed to identify clinical factors associated with IOP elevation. Results: Mean IOP significantly increased from 13.9 ± 3.3 mmHg at baseline to 39.2 ± 12.4 mmHg immediately after injection (p < 0.001), with 79.7% of eyes showing an IOP ≥ 25 mmHg. Among those remeasured, IOP decreased to 17.7 ± 6.5 mmHg at 30 min. Significant differences in IOP elevation were observed among anti-VEGF agents (p < 0.001), with aflibercept at 2 mg and 8 mg showing greater increases than other agents. Multivariate analysis identified higher baseline IOP, history of glaucoma, absence of prior vitrectomy, and use of aflibercept (2 mg or 8 mg) as significant risk factors for greater post-injection IOP elevation. Conclusions: Transient IOP elevation ≥ 25 mmHg was observed in the majority of eyes after IVI but typically resolved within 30 min. Aflibercept use, high baseline IOP, glaucoma history, and absence of prior vitrectomy were associated with greater IOP elevation. Careful monitoring and attention to injection volume may be warranted, particularly in high-risk patients.