Phacoemulsification and thermal wound injury.

The technique of lens nucleus phacoemulsification has revolutionized cataract surgery. However, the production of ultrasound energy is associated with heat generation that can result in damage to ocular tissue, in particular the corneoscleral wound site. Thermal damage to the corneoscleral wound site may result in difficulty with wound closure and consequent risk of wound leakage, as well as damage to the adjacent corneal stroma and endothelium, fistula formation, and the induction of high degrees of post-operative astigmatism. The loss of adequate flow of irrigation fluid around the phacoemulsification tip is the key factor in the development of phacoemulsification-induced thermal injury. Use of excessive ultrasound power and production of excessive frictional forces generated by contact of the vibrating phacoemulsification needle with the irrigation sleeve are also factors involved. In the event of a "phacoburn," a specialized "gape suture" may help minimize surgically-induced astigmatism. The degree of induced astigmatism tends to wane over time; astigmatic keratotomy is an option in the setting of high degrees of residual astigmatism.