Histopathology And Risk Factors For Corneal Wound Burns Created During In Vitro Phacoemulsification

Abstract

Purpose: : To evaluate the histopathology of corneal wound burns created by in vitro phacoemulsification and examine the optimal conditions for developing corneal thermal injury during in vitro phacoemulsification.

Methods: : Phacoemulsification using the Bausch and Lomb Millennium^TM system with the Concentrix^TM Pump was performed on pig eyes warmed to room temperature. A clear cornea incision was made near the limbus and viscoelastic agent (hyaluronic acid–chondroitin sulfate) was infused into the anterior chamber. Phacoemulsification settings (irrigation, ultrasound power, vacuum, and aspiration) and surgical conditions (incision size, phaco tip position) were adjusted to determine the optimal conditions for creating a corneal wound burn. Continuous phacoemulsification was performed using variable settings until a visible corneal wound burn was created or until the entire lens was aspirated. Representative sections of corneas with and without visible corneal wound burns were stained with hematoxylin and eosin and then examined.

Results: : The histopathology of clinically visible corneal wound burns showed basophilic staining of the corneal stroma with contraction. Corneal burns occurred with 2.8 mm and 3.0 mm incisions, using ultrasound power at 40%, vacuum at 30 mmHg, maximum aspiration flow rate of 25 ml/min and irrigation off. The corneal burns occurred at 30 seconds and 32 seconds of phacoemulsification, respectively. When irrigation was turned on, corneal burns did not occur with both incision sizes, power increased to 50%, vacuum increased to 60 mmHg, and maximum aspiration flow rate of 25 ml/min.

Conclusions: : Phacoemulsification thermal injury causes structural damage to the corneal stroma as evident on histopathologic examination. The histopathology of corneal wound burns correlates with the gross appearance of corneas. Occlusion of irrigation is a significant factor in developing corneal wound burns during in vitro phacoemulsification.

Keywords: cornea: clinical science • cornea: stroma and keratocytes • pathology: experimental