Corneal tissue flap could cause leakage with clear corneal incision

Everted triangular flap of posterior corneal stroma hindered proper wound alignment and self-sealing after phaco, study finds.

Issue: September 15, 2007

ByErin L. Boyle

A corneal “tongue,” or everted flap of posterior corneal tissue, may result in wound incompetence after phacoemulsification with a clear corneal incision, a study found.

The “tongue” is a potential risk with sutured incisions and sutureless, self-sealing incisions, Ayman Naseri, MD, said.

“I do not know how common this is because the incidence has not been studied,” Dr. Naseri said in a telephone interview with Ocular Surgery News. “But once we started looking for wounds with a tongue, we identified them relatively frequently, at least in our patient population. My clinical impression is that it’s more common than people realize.”

Researchers conducted an observational case series involving three patients who had wound leaks after undergoing phaco with clear corneal incisions.

Study results underscored the lack of data on how wound architecture may affect wound leakage and the risk of endophthalmitis.

“Although postoperative wound leak has been strongly associated with endophthalmitis, little focus has been directed to potential flaws in wound architecture,” the authors said in the American Journal of Ophthalmology.

Sutured vs. sutureless incision

Two surgeons operated on the three patients. In each case, they created a deep-grooved, hinged clear corneal incision with a diamond keratome, according to the study.

The first patient was a 76-year-old man with a Seidel positive wound in the left eye on the first day after surgery. Uncorrected visual acuity was 20/40, and IOP was 17 mm Hg. Physicians patched the eye, and it was Seidel negative the next day.

The second patient, a 78-year-old man, had a clear corneal incision sealed without stromal hydration or suture. He had occasional fluid leakage starting 9 days after surgery. UCVA was 20/25, and IOP measured 10 mm Hg. His wound had to be revised.

The third patient was a 75-year-old man whose incision leaked without stromal hydration at the end of surgery and required a 10-0 nylon suture. His best corrected visual acuity was 20/100, and IOP measured 11 mm Hg. His wound was Seidel positive 16 days after surgery and also required revision surgery.

After surgery, researchers used Seidel testing to detect wound leakage. Aqueous fluid leakage through such a wound is often subtle and easy to miss, Dr. Naseri told OSN.

“You’ll notice that these patients had relatively normal eye pressures,” he said. “When you think of a wound leak, you think of an eye that would have a low eye pressure. But our patients had relatively normal eye pressures. The fluid leakage is often subtle, so unless you do Seidel testing, you may not identify it.”

The researchers found two mechanisms causing the corneal tongue: the incision path into the anterior chamber and the creation of a small posterior tear through wound manipulation, Dr. Naseri said. The first mechanism is more common, he noted.

The corneal tongue folds within the wound, hindering tissue apposition and self-sealing, the authors said.

Figure 1: Clear corneal wound of Case 1
Clear corneal wound of Case 1 after uncomplicated phaco. (Top left) The wound demonstrates an everted corneal tongue. (Bottom left) The same wound shown with a schematic overlay of the everted type I clear corneal tongue. (Top right) Slit-beam shows thinning of the internal aspect of the wound (filled arrowhead) and thickening of the peripheral cornea (empty arrowhead) from the everted tissue. (Bottom right) Ultrasound biomicroscopy demonstrates a disruption in acoustic reflectivity of the Descemet membrane and associated thinning corresponding to the folded tongue (arrow).

Figure 2: Clear corneal wound of Case 3
Clear corneal wound of Case 3 after uncomplicated phaco with a 10-0 nylon suture. At left, the internal tip of the corneal tongue is seen protruding from the wound (arrowheads). At right, Seidel positivity of the same wound.

Figure 3: A schematic illustration of the two types of corneal tongues
A schematic illustration of the two types of corneal tongues that can be created during clear corneal wound construction for phaco. At left, a type I corneal tongue is observed when the internal hinge of the corneal flap is preserved; the tissue usually remains within the length of the incision (see Figure 1). At right, in type II, a tear along the lateral aspect of the tunneled wound allows for a longer tongue of tissue that may even protrude at the ocular surface, especially with short incisions (see Figure 2).

Images: Reprinted from the American Journal of Ophthalmology, Vol. 143, No 3, Diamond Y Tam, MD, M. Reza Vagefi, MD and Ayman Naseri, MD, The Clear Corneal Tongue: A Mechanism for Wound Incompetence after Phacoemulsification, 526-528, Copyright 2007, with permission from Elsevier.

Risks debated

There is no consensus among surgeons on the risks of sutureless corneal incisions, Dr. Naseri said. The study showed that a sutured incision with a corneal tongue may leak and become infected.

“It’s still debated,” he said. “There are studies that suggest that an incision without a suture can increase the risk of endophthalmitis. … Some say that if you have a wound without a suture, you’re at increased risk of having a wound leak and, therefore, getting an infection. But what our case shows is that even with a suture, you can still have a leak, if you have this [corneal] tongue problem.”

A self-sealing wound may not leak immediately after surgery, Dr. Naseri said.

“The bottom line is that a wound that appears to be self-sealed at the end of surgery can actually leak after surgery,” he said.

For more information:

Ayman Naseri, MD, can be reached at Department of Ophthalmology, University of California, San Francisco, CA 94143; 415-476-0678; fax: 415-379-5590; e-mail: Ayman.Naseri@va.gov. Dr. Naseri has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.

Reference:

Naseri A, Tam DY, Vagefi MR. The clear corneal tongue: A mechanism for wound incompetence after phacoemulsification. Am J Ophthalmol. 2007;143:526-528.

Matt Hasson is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses on regulatory, legislative and practice management topics.