Experimental Analysis Of Parameters Influencing The Postoperative Incision Size Due To Intraocular Lens Injector Insertion

Clear corneal incisions enlarge during cataract surgery due to intraocular lens (IOL) injector insertion. A larger postoperative incision size is associated with a higher risk for surgically induced astigmatism and endophthalmitis. The goal of this study was to determine the parameters that influence the postoperative incision size.

The David J Apple International Laboratory for Ocular Pathology, University of Heidelberg, Heidelberg, Germany.

In this experimental study 499 clear corneal incisions in ex vivo porcine eyes and 126 IOL injectors of 13 different injector models were included. In every IOL injector model, the vertical diameter and the angle of the injector tip was measured. The corneal thickness of each incision location was measured using Scheimpflug tomography. The incision size of each corneal incision was measured before and after injector insertion and described as preoperative and postoperative incision size, respectively. During surgery, the insertion depth and incision length were documented. A mixed effects model was applied to analyze the influence of the parameters on the postoperative incision size.

An increase in vertical diameter of the injector tip, preoperative incision size and insertion depth, and a reduction of incision length were significantly associated with a larger postoperative incision size (p<0.05). The conditional Pseudo-R²-Measure was 0.92. The preoperative incision size had the largest estimated effect in relation to the other parameters on the postoperative incision size, followed by the vertical diameter of the injector tip, the insertion depth and lastly the incision length. The parameters corneal thickness and tip angle of an IOL injector did not have a significant effect on the postoperative incision size (p>0.05).

The vertical diameter in IOL injector systems should be as small as possible to ensure a minimal postoperative incision size. During cataract surgery, the insertion depth of an injector should be held to a minimum and the incision length should be long enough to reduce the postoperative incision size. Further studies are needed to confirm the findings in human eyes.