Abstract
Purpose: :
To investigate the rate of intra-ocular pressure change following an intra-vitreal injection of ranibizumab (Lucentis) during the immediate (ie: 1-15 minutes) post injection period.
Methods: :
The medical records of patients in a private retinal practice receiving intra-vitreal injections of Lucentis for wet age-related macular degeneration (ARMD) between October 1, 2007 and October 31, 2008 were retrospectively reviewed for post-injection IOP spikes. Glaucoma patients were excluded from this review. A 0.05 ml dose of Lucentis was injected through the inferiotemporal pars plana with the patient seated at the slit lamp; this allowed direct visualization of the drug entering the vitreous cavity. Intra-ocular pressure was measured immediately (within 1 minute) after the injection by Goldmann applanation tonometry. In those instances where the IOP was greater than 35 mmHg the IOP was rechecked by the same examiner on the same instrument between 5 and 16 minutes later. The difference between these two reading was divided by the time between them to get the slope of the line. The mean, standard deviation, maximum, and minimum values were calculated and plotted.
Results: :
A total of 73 injections were included in this study. The mean immediate post-injection IOP was 52.5 mmHg (std dev 9.75, range 35-72 mmHg). After a time interval ranging from 5 to 16 minutes (mean 8.0, std dev 2.6 minutes) the mean IOP had fallen to 26.2 mmHg (std dev 6.5, range 13-43). The mean rate of IOP decline (slope) was 3.40 mmHg / min (std dev 1.11, range 1.25 to 6.00 mmHg / min). The correlation between the immediate post-injection IOP and the rate of IOP decline was r=0.647 (p=0.0001).
Conclusions: :
Lucentis' safety record has been well established and the need for monitoring post-injection IOP has been questioned. We looked at individual patients who had IOP elevations to greater than 35 mmHg immediately after an intra-vitreal injection of Lucentis and calculated the rate of IOP decline over the first few minutes following the injection. The rate of IOP decline was correlated to the immediate post-injection IOP, with steeper slopes noted for higher pressures. We suggest that patients who have an IOP decline rate slower than about 2.25 mmHg/minute (our mean of 3.4 mmHg - 1 std dev, rounded to the nearest quarter mmHg) may be candidates for IOP lowering intervention, while patients with faster IOP decline rates are unlikely to require such intervention. Hopefully, this information will allow for better management of patients receiving intra-vitreal Lucentis injections in a private office setting.
Keywords: vascular endothelial growth factor • injection • drug toxicity/drug effects