Why infections related to PK require intense vigilance

June 1, 2016

The causes of infections associated with penetrating keratoplasty are evolving, but no matter what the etiology, these infections consistently require vigilance and aggressive treatment.

Reviewed by Bennie H. Jeng, MD

Baltimore-Infections associated with penetrating keratoplasty (PK) require careful monitoring and an examination into the cause of the infection, said Bennie H. Jeng, MD.

Specific types of infection include microbial keratitis, endophthalmitis, recurrence of viral infection, and transmission of infections from the donor, said Dr. Jeng, professor and chairman, Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore.

To highlight infection risks related to PK, Dr. Jeng shared the case of a 53-year-old woman treated for a contact lens-related Pseudomonas corneal ulcer in the right eye. After the infection cleared, the patient developed a new infiltrate that the referring ophthalmologist thought looked a little different.

Related: Differentiating among mosquito-borne forms of uveitis

Although culturing identified it as fungus, its specific species could not be pinpointed. She was started on hourly voriconazole 1% and natamycin for recalcitrant infection.

The infection still progressed, and a deep anterior lamellar keratoplasty was performed to debulk the infection. Postoperatively, she was started on prednisolone acetate 1% and gatifloxacin.

Still, the patient’s infection persisted, and she was referred to the office of Dr. Jeng and colleagues. Despite aggressive therapy including topical, intracameral, and oral antifungal agents, therapeutic PK was required to treat the infection.

“Unfortunately, the patient had started herself on topical steroids immediately postoperatively,” Dr. Jeng said. “So, as you’d expect, there was recurrence of the infection by day six.”

More: Cosmetic iris implants dubbed ‘public safety hazard’

The infection still wasn’t controlled with intracameral injections of antifungals. Five days later, a limbus-to-limbus PK was performed along with irrigation of the anterior chamber with antifungals.

Postoperatively, the patient was put on oral antifungals.

The infection was “surprisingly sensitive” to voriconazole and amphotericin, Dr. Jeng said. “I think the infection was hiding deep in the cornea.”

The limbus-to-limbus graft eventually failed, and a 7 mm PK and cataract extraction was performed. Ultimately, she was regrafted once more, but at four years after original presentation, the patient’s best spectacle-corrected visual acuity was 20/25.

Dr. Jeng said that his case touched upon a series of risks associated with infection in the setting of PK.

Microbial keratitis

 

Microbial keratitis can arise from a contaminated donor button, although Dr. Jeng said that is happening much less frequently.

However, surgeons should also be aware of the increasing risk of fungal infections (some transmitted from the donor) compared with bacterial infections, based on data from the Eye Bank Association of America, Dr. Jeng said.

Related: When is crosslinking appropriate?

“One possible reason for the rise in fungal infections is that endothelial keratoplasty is on the rise, and fungus love living in that interface because they are protected,” he said.

Something that he does see more often is the recurrence of a host infection, which could be modulated by the use of certain postoperative medications like steroids. Late infections could be caused by suture-related problems, persistent epithelial defects, chronic use of bandage contact lenses, ocular surface disease, and eyelid and adnexal abnormalities.

Which is superior: LASIK or contact lenses?

“We need to identify these infections very early on and culture them,” Dr. Jeng said. “Any small infection in the graft needs to be treated aggressively.”

He prefers to use fortified antibiotics because of the risk of graft wound dehiscence if the infection progresses.

“I’ll decrease steroids if they’re on it,” Dr. Jeng said. “If a suture is involved, I’ll remove it. If it’s necessary to regraft, I’ll do it.”

Although there is less risk nowadays for viral infections, it still is possible for patients to get a recurrent or new onset herpetic infection transmitted from the donor, Dr. Jeng said.

There were previous reported cases of hepatitis B transmission, but with stringent eye bank screening in the last few decades, this infection seems to be a thing of the past. And fortunately, there have been no documented cases of HIV transmission via a graft to date, Dr. Jeng said.

 

More articles:

Ocular surface unfriendly to pathogenic bacteria

Pre-existing glaucoma poses considerations for corneal procedures

In-office treatments for MGD may provide relief

Binkhorst Lecture: Predicting, treating keratoconus in 2016

 

Bennie H. Jeng, MD

E: BJeng@som.umaryland.edu

This article was adapted from Dr. Jeng’s presentation at the 2015 meeting of the American Academy of Ophthalmology. Dr. Jeng did not indicate any proprietary interest in the subject matter.