JAN 17, 2012
Investigators retrospectively evaluated the long-term effect of intravitreal injections of anti-VEGF agents on IOP. They found a significant positive correlation between the number of injections and the probability of experiencing IOP elevation >5 mmHg above baseline IOP on ≥2 consecutive visits.
They reviewed the charts of 207 patients treated in one eye for wet AMD. Fellow eyes served as controls. Patients were treated with at least three intravitreal injections of ranibizumab (0.5 mg/0.05 ml) and/or bevacizumab (1.25 mg/0.05 ml).
They found that 11.6 percent of treated eyes experienced IOP elevation of >5 mmHg on at least two consecutive visits, compared with 5.3 percent of controls. Receiving ≥29 injections increased the odds of IOP elevation almost six-fold compared with receiving ≤12 injections. Total number of injections was the only factor significantly associated with IOP elevation >5 mmHg above baseline on at least two consecutive visits (P = 0.05).
Among several theories on the cause of IOP rise associated with anti-VEGF injection, are: a pharmacologic effect of VEGF blockade, an inflammatory mechanism/trabeculitis, impaired outflow owing to protein aggregates/silicone droplet debris, and damage to outflow pathways due to the repeated trauma and/or IOP spikes associated with the injection procedure.
The authors recommend routine monitoring of pre-injection IOP in all patients receiving anti-VEGF therapy.