Clear Cornea and Endophthalmitis
What the Moran Eye Center study revealed about the connection.
By Ophthalmology Management staff

When the surgeons at the John A. Moran Eye Center completed their 4-year prospective analysis of endophthalmitis at their facility, they were struck by the number of cases recorded: 21 in 9,079 cataract surgeries. While that rate isn't unheard of, it was slightly more than double what they had expected.

Their study was a quality control project in which they reviewed all cases of endophthalmitis to ascertain whether they could identify reasons why the cases occurred and what they could do differently in the future to prevent them. "We evaluated each case in detail and held them in a database," explained Randall Olson, M.D., director of the center, which is part of the University of Utah School of Medicine. "This was a period of time in which topical anesthesia and clear cornea surgery were the overwhelming choices of surgeons at our institution."

The results of the study, presented for the first time at this year's ARVO meeting, add credence to the theory that the increase in clear cornea cataract procedures and an increase in endophthalmitis are somehow linked. "It's becoming increasingly recognized that this is an issue," Dr. Olson said. "Anecdotally, retinal groups have been talking about this for a while. They've been seeing a lot more endophthalmitis than they used to."

What's the connection?

Dr. Olson is convinced that the culprit is microleaks in the wounds following clear cornea, sutureless procedures. "These microleaks can be relatively brief, and I think they often occur in the early post-op stage, possibly in the first 24 hours. During that time, you have the potential for intraocular contamination."

One of the keys to preventing endophthalmitis, he said, is to be absolutely sure that you have a tightly closed wound. And if you don't, or if you're not sure, use a stitch. "A tightly closed wound is crucial," he said. "Not one that you have to push to tighten, but one that you can easily see is sealed. I think that because so many of these patients look fine the next day, surgeons have been leaving marginal wounds alone, and that's part of the reason we're having difficulties."

Dr. Olson recommends examining each wound closely. If you don't, he said, it's easy to miss things like small tears in Descemet's membrane. "You can stromally hydrate a wound to help seal it, but the hydration doesn't last very long, and many leaks won't resolve in that amount of time," he said. "So I'm careful to check for tears and often likely to put a stitch in."

To test wounds after his clear cornea procedures, Dr. Olson inflates the anterior chamber, changes to irrigation only, and quickly pulls out of the eye. "If the wound block slaps right down and seals, I know I have a wound that I don't have to worry about." Those are the wounds he has the most confidence in, he said, but they don't happen in every case. So, in general, he slightly hydrates the stroma to see whether the wound seals, to make sure he doesn't see anything abnormal about the wound and to ensure that he's happy with the wound architecture. He then presses on the eye to see that with pressure, and the release of pressure, the wound stays well sealed.

"I also make sure the eye isn't overly inflated," he said. "By raising the pressure too high, you can actually force the wound together, and then when the pressure comes down it opens up. If the wound passes all of those tests, I don't have to put a stitch in. But in cases where we have marginal wounds, I think we err if we don't take the time to put in a simple stitch that we can easily remove the next day or in a week."

As far as incision location, Dr. Olson said he has moved his slightly more posterior, without moving well back into the limbus. "If you move too far back, often you'll get a little more bleeding and sometimes more irritation for the patient. People will argue one way or the other, but I think that a clear cornea incision appropriately constructed and looked at in detail will be safe. All else being equal, going a little more into the limbal tissue will give you better healing and will potentially seal the wound a little faster. But a poorly constructed wound in either place will get you into trouble."

Now that we know

Dr. Olson said that in addition to illustrating the importance of preventing wound leaks, the Moran study showed ­ for the first time to his knowledge ­ that choice of perioperative topical antibiotic does have an impact on the incidence of endophthalmitis. (See "Also From the Study". )

In light of the new information, he said, surgeons need to focus on the idea that "the incidence of endophthalmitis can easily be higher with clear cornea, but it doesn't have to be."