Neutrophils promote bacterial clearance; however, their by-products are potentially destructive to adjacent tissue and the retina.
"It has long been thought that . . . steroids might be potentially beneficial for treating endophthalmitis and may mitigate retinal damage and ultimately improve visual outcomes," said Dr. Busbee, a physician partner with Tennessee Retina located in Nashville.
The Endophthalmitis Vitrectomy Study (EVS) did not provide any good direction about the use of intravitreal or sub-Tenon's steroid injections, only topical and oral formulations and the correct choice of antibiotics, he noted.
Before the EVS, some surgeons used dexamethasone, and studies have suggested that a surgeon should not use more than 400 µg of the drug. Following the EVS, there was no real change in surgeon practices in the use of dexamethasone and study results on its benefits are conflicting, according to Dr. Busbee.
There are no definitive answers because the incidence of endophthalmitis is so low. Most reports have been case studies or retrospective reviews.
"We are going to have to rely on levels of evidence that are less than Level 1 evidence to decide what is best for our patients," he said.
Dr. Busbee reviewed a few studies of postoperative endophthalmitis in which dexamethasone was used. A retrospective review by Shah et al. in 2000 included 57 patients, 31 of whom were treated with dexamethasone. The study found that intravitreal dexamethasone administered at the time of acute endophthalmitis reduced the likelihood of patients achieving a three-line gain in visual acuity.
Another study of dexamethasone published in 2005 by Gan et al. included 29 patients randomly assigned to antibiotics and steroid or antibiotics alone. Patients received two injections of dexamethasone 3 days apart. An evaluation of the visual gains at 3 and 12 months after treatment concluded that there was a trend toward better vision when treated with dexamethasone.
A third study by Albrecht et al. published in 2011 found that 60 patients did not appear to have any visual benefit from dexamethasone, but the drug appeared to be safe.
In a 2006 study of intravitreal triamcinolone in 14 patients, Falk et al. concluded that the drug was safe, and patients achieved a mean gain in visual acuity of more than 7 Snellen lines.
New drugs on the block
Alternative new treatments include topical difluprednate emulsion (Durezol, Alcon Laboratories), which can be stopped quickly if an alteration in management is deemed appropriate. Extraocular sub-Tenon's triamcinolone (Triesence, Alcon) is another alternative to mitigate the inflammatory response. Finally, systemic antibiotics with higher penetration into the ocular cavity, such as the fourth-generation fluoroquinolones (Avelox, Bayer), are another potentially beneficial option, Dr. Busbee noted.
The current situation with steroids seems to indicate that the jury is still out. Use of steroids has been reported in fewer than 200 patients with endophthalmitis. The results of studies on the benefits of the use of steroids in these patients have been conflicting. No clear benefit for the use of dexamethasone has been reported. Judicious application of steroids is recommended. New therapeutic agents should also be considered, Dr. Busbee summarized.
Dr. Busbee has no financial interest in the subject matter.