Experimental bacterial endophthalmitis following extracapsular lens extraction

The rapid increase in popularity of extracapsular cataract extraction may predispose the eye to postoperative bacterial infections by introducing viable organisms through the additional instrumentation and irrigation necessary for the extracapsular technique. Lens protein released into the aqueous humor of the anterior and posterior chambers may enhance or inhibit the ability of organisms to grow in the aqueous humor. In the intact eye the lens acts as a significant protective barrier restricting the posterior extension of the infectious processes. This study was undertaken to determine if extracapsular lens extraction enhances the ability of common bacteria to infect the anterior segment of the eye and if the posterior lens capsule acts as a protective barrier denying the infectious process access to the vitreous body. Approximately 1000 colony forming units (CFU) of Staphylococcus aureus were required to produce bacterial endophthalmitis in less than one-half of normal rabbit eyes and eyes following extracapsular lens extraction. Discission of the posterior lens capsule tripled the number of eyes infected. As few as fourteen CFU could produce infections in some eyes if the posterior capsule was incised. Extracapsular lens extraction does not predispose the eye to bacterial endophthalmitis if the posterior lens capsule remains intact. Interruption of the posterior lens capsule does allow a small number of organisms to establish an intraocular infective process. Lens protein and other constituents released into the aqueous humour appear to have little effect on the growth of the test organisms.