Purpose
There is debate in the ophthalmology community about whether anti-VEGF injections result in a long-term increase in intraocular pressure (IOP). Some studies have identified risk factors (i.e. number of injections, interval between injections) that are associated with elevated IOP, while other studies have shown that intravitreal anti-VEGF injections do not lead to elevated IOP. We performed a retrospective, observational clinical study to investigate how the number and timing of intravitreal injections for patients with age-related macular degeneration (AMD) and diabetic macular edema (DME) affect IOP over time.
Methods
After receiving IRB approval, we collected long-term IOP data on patients receiving anti-VEGF injections at the University of Chicago. Patients over the age of 40 who received the injections for AMD (n = 76) or DME (n = 55) were included in the study; those receiving injections for retinal vein occlusion were excluded. Patients were grouped according to indication for injection as well as number of injections received (1-3, 4-6, 7-9, or 10+ injections). IOP measurements were then placed into time points (0-6, 6-12, 12-18, 18-24, or 24+ months after first injection) and compared to the pre-injection IOP. One-tailed t-tests were used for statistical analysis.
Results
For patients with DME, average initial IOP was 15.7 mmHg. At 24+ months after injection, the average IOP was 15.2 (95% CI: 13.8-16.6, p = 0.68) for patients receiving 1-3 injections, 16.8 (15.3-18.3, p = 0.23) for 4-6 injections, and 14.4 (13.8 - 15.0, p = 0.66) for 7-9 injections. For patients with AMD, average initial IOP was 15.6 mmHg. At 24+ months after injection, the average IOP was 12.6 (95% CI: 10.8-14.4, p = 0.97) for patients receiving 1-3 injections, 14.9 (13.7-16.1, p = 0.96) for 4-6 injections, 14.8 (12.4-17.2, p = 0.84) for 7-9 injections, and 15.7 (14.0-17.4, p=0.56) for 10+ injections.
Conclusions
There was no statistically significant increase in IOP over time for AMD or DME patients, regardless of the number injections received. Ours is the only study we are aware of to track the progression of IOP over a period of greater than two years and to stratify by number of injections received. It is notable that neither of these variables affected IOP, as they have been proposed as potential factors contributing to increased IOP after injections