Results of a study evaluating post-cataract surgery endophthalmitis at a regional tertiary referral centre in England show no evidence of an increase in incidence over a recent period of almost eight years, reported Omar M. Durrani, FRCS.
The retrospective investigation extracted information from a computerized database of surgical activity, case notes, and the hospital morbidity coding system at the Birmingham & Midland Eye Centre, Birmingham, England, which serves a population of about three million. The study analysed consecutive cases of endophthalmitis occurring between April 1997 and November 2004. Eyes were included if they presented with features of endophthalmitis within six weeks following cataract surgery.
A total of 101 cases were identified among 101,920 total procedures, yielding an overall annual incidence of post-cataract surgery endophthalmitis of 0.099%. Analyses of annual incidence rates for each year of the study showed some fluctuation, with rates ranging from a low of 0.053% to a maximum of 0.191%.
"The incidence of post-cataract surgery endophthalmitis has been reported to have increased over the past 15 to 20 years, perhaps as a result of conversion to clear cornea surgery," said Durrani, clinical lecturer, University of Birmingham, UK. "That background prompted us to conduct a study to determine the incidence of this rare-but-devastating complication in our own regional centre.
"Our study has limitations that make it difficult to draw conclusions," he conceded. "Its sample size is relatively small compared with the recently reported Medicare billing data study. It also represents experience of surgeons with varying levels of expertise using different draping practices and working in more than a dozen operating suites.
"However, those features also make our study quite robust because it represents a real-world setting," continued Durrani, who is also an oculoplastic and orbital fellow at Moorfield's Eye Hospital, London, UK. "Perhaps routine use of preoperative skin cleaning and fornix irrigation with povidone-iodine is one explanation for the observed stability in the endophthalmitis rate at our centre."
The 101 cases of post-cataract surgery endophthalmitis occurred among patients with a mean age of 71 years (range 24 to 94). The affected patients were predominantly female (about two-thirds), and there was a preponderance of left versus right eyes (61 versus 40).
"We found the predominance of left eyes to be very interesting and wonder whether that is due to the fact that the paracentesis lies in the palpebral aperture and, perhaps, is exposed," Durrani said. "In the future, we also hope to analyse our data further to see if any surgery-related variables influenced the risk of endophthalmitis."
What's the best way of diagnosing it?
The additional 15 cases occurred during the same timeframe after intraocular surgical procedures other than cataract extraction, but excluded eyes with post-traumatic or endogenous endophthalmitis as well as those with microbial keratitis.