Accuracy and Precision of Intraocular Injection Volume

Purpose: To assess the accuracy and precision of methods in clinical use for intraocular drug injection.

Design: Experimental laboratory investigation.

Methods: A total of 800 injections were performed using 20 different 1-ml syringes at intended volumes of 0.10 ml and 0.05 ml. The volume of each injection was calculated from mass of water delivered onto an analytic balance.

Results: The mean measured volume delivered was less than the intended volume for every syringe (P <.001 for each syringe at each volume). A total of 7% and 22% of injections differed by 20% or more from the intended volumes of 0.10 ml and 0.05 ml, respectively. Overdelivery of volume was uncommon.

Conclusion: Clinically relevant materials and methods used for intraocular injection of drugs systematically underdelivered the intended volume.