Corneal Wound Burns - Rare but Serious Complications of Phacoemulsification Surgery.
Description:Corneal wound contracture, also called corneal wound burn or phaco burn, is a rare but severe complication that can occur with cataract operation [1]. Epidemiological studies indicate an occurrence of less than 0.037% in all cataract surgeries (or 1 : 3 000). It describes a coagulation of the phaco tunnel caused by excessive heat generated by the phaco needle during phacoemulsification [2]. Temperatures above 60 °C cause a destruction of the collagen fibres in the corneal stroma [2], [3], [4]. This causes necrosis, which results in corneal oedema. A corneal wound burn results from a combination of excessive heat generated by the phaco needle as well as insufficient cooling by irrigation fluid [1], [5], [6]. Signs of phaco burn include a sudden occurrence of corneal oedema around the phaco tunnel, with gaping wound lips and an increasingly instable anterior chamber [7], [8]. The phacoemulsification technique plays a major role for the occurrence of phaco burns. Risk factors include increased phacoemulsification time and high phacoemulsification energy [9], [10]. Consequently, chopping techniques have been reported to bear a lower risk for phaco burns than divide and conquer techniques due to less phaco energy needed [9], [10]. Another factor predisposing the possibility of a corneal wound burn is the width of the phaco tunnel. If the tunnel is too narrow, the irrigation ports will be pressed against the walls of the tunnel during phacoemulsification [3]. This can result in a blockage of irrigation, which can lead to temperature increase of the phaco needle. Ocular viscoelastic devices (OVDs) can also cause blockage of the irrigation ports. Furthermore, the energy released by phacoemulsification varies depending on the OVD used, with higher density OVDs carrying a higher risk of phaco burn [4]. Finally, overfilling the anterior chamber with an OVD reduces flow of irrigation fluid and increases the risk of excessive heat buildup [4]. In the this article, we present a case series of five eyes of five patients that developed a corneal wound burn during cataract surgery and were referred as an emergency to the Department of Ophthalmology of the University Hospital Zurich, University of Zurich, Switzerland. An overview of the cases and the respective treatments, complications, and outcomes are given in [Table 1].









