Chicago?Available evidence from a series of studies indicates sutureless clear corneal incisions (CCIs) may be an independent risk factor for acute endophthalmitis after cataract surgery, said Peter J. McDonnell, MD, at the annual meeting of the American Academy of Ophthalmology.
"Clearly, small-incision cataract surgery with a clear cornea approach has been a dramatic advance in terms of cost-effective delivery of health care and visual rehabilitation of cataract patients. Therefore, the challenge we face is to retain the advantages of this technique but to come up with a strategy to address its potential risk," said Dr. McDonnell, William Holland Wilmer professor and director, Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore.
"Studies from our institution show the transition to CCI was temporally associated with an increase in endophthalmitis and provide plausibility for a causal role, but they do not prove a cause-and-effect relationship. However, the evidence causes us to recommend consideration of suture closure, especially in eyes with trabeculectomy and low IOP in the postoperative period."
Consequently, ophthalmologists at Wilmer conducted a series of studies to investigate an association between CCI and endophthalmitis risk.
Mehran Taban, MD, and colleagues conducted a systematic review of the peer-reviewed, English-language literature published between 1964 and 2002 to determine temporal patterns in the reported rate of acute endophthalmitis after cataract surgery (Taban M, et al. Arch Ophthalmol 2005;123:613-620). During the first 3 decades of the study, meta-analysis results showed a gradual downtrend but that appeared to reverse in 1992. In addition, the investigation found the rate of endophthalmitis with CCI surgery for the period from 1992 to 2003 was roughly 2.5-to 3-fold higher than that reported during the same years when surgery was performed with either scleral tunnel or limbal incisions.
Emily West, PhD, and colleagues conducted a study examining the Medicare database for cases of endophthalmitis between 1994 and 2001 (West ES, et al. Ophthalmology 2005;112:1388-1394). That investigation showed the rate of acute endophthalmitis increased significantly from 0.18% (1.8 cases per thousand per year) between 1994 and 1997 to 0.25% (2.5 cases per thousand per year) between 1998 and 2001.
Other studies were undertaken in the laboratory and operating room to examine the potential for ocular surface fluid to traverse the stroma of a CCI and gain access into the anterior chamber. Using the Miyake view and removing iris and uveal tissue from eye bank eyes to allow examination of the CCI wound site from a posterior aspect, India ink was applied to the ocular surface as a marker for fluid flow (Taban M, et al. Arch Ophthalmol 2005; 123:643-648). After application and release of digital pressure, to mimic the clinical situation of a patient applying pressure to the lid when instilling drops into the eye, as well as with lowering of the infusion cannula to create fluctuations in IOP, entry of small jets of India ink through the CCI and into the anterior chamber was observed in about one-third of eyes.
"Histopathologic examination showed ink particles marked the edges of the incision and were embedded in the interstices of the stromal lamella, suggesting that these particles could migrate through the stromal incision in wounds that appeared clinically to be patent," Dr. McDonnell said.
In a clinical study, eyes were evaluated that had undergone cataract surgery through a 2.8-mm limbal incision and that had minimal bleeding from the limbal capillary bed (Herretes S, et al. Am J Ophthalmol 2005; 140:737-740). After wound hydrosealing, application and release of digital pressure on the globe resulted in an inflow of blood-tinged surface fluid into the anterior chamber.
"In some cases, small jets of blood could even be seen entering the eye spontaneously as a result of ocular pulse-associated pressure fluctuations," Dr. McDonnell said.