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Rare infections after PRK, LASIK require aggressive therapy
The case and discussion published in the cover story is from the annual Sunday Corneal Health Round Table held at OSN New York 2017 and moderated by Eric Donnenfeld, MD. For those who have not attended the OSN New York meeting, it takes place every fall at the Sheraton Hotel in Manhattan near Times Square and includes a clinician-focused update on all the specialties important to a comprehensive ophthalmologist. It is a great meeting and a fun time to visit New York. The case presented here includes many lessons, most of which were discussed by the panelists. I will add a few personal thoughts.
The patient who undergoes PRK is at risk for infection. The rate is approximately one per 1,000. For LASIK, it is closer to one per 5,000, so infections are rarer after LASIK. Still, antibiotic prophylaxis is appropriate for both groups. A number of years ago, the most likely organism to be found was atypical mycobacterium. A switch to fluoroquinolones as the antibiotic of choice has nearly eliminated this organism. Today, the most likely pathogen is a Staphylococcus species, many of which are methicillin resistant, such as MRSA and MRSE.
The differential diagnosis for a patient who presents after PRK with an infiltrate includes the possibility of a sterile infiltrate occurring in the face of a bandage contact lens and topical NSAID use, which increases leukotriene tissue concentrations and polymorphonuclear leukocyte recruitment. My treatment for a sterile infiltrate is to remove the bandage contact lens, discontinue the topical NSAID, and increase the steroid drop frequency or potency. I will cover with an antibiotic, usually a fluoroquinolone. Unfortunately, it requires a negative Gram and Giemsa stain and culture to be sure the infiltrate is sterile, so we are forced to treat as though it is infectious. The top suspicion is a methicillin-resistant staph (MRSA and MRSE), so therapy should be directed at this organism. I find Polytrim (polymyxin B and trimethoprim, Allergan) a readily available and inexpensive drop to add to my fluoroquinolone. Bacitracin ophthalmic ointment at night and repeated when waking during the night is another very effective agent against staph, including MRSA and MRSE.
The bandage contact lens and NSAID drops are discontinued, but the steroids are still given, as several studies suggest that they do not negatively impact the treatment of bacterial keratitis. If the infiltrate pattern is highly suggestive of something unusual such as a fungal species with multiple satellite lesions, I will discontinue the steroids, but in most cases I continue them until culture results are obtained as they reduce the risk of a corneal scar. Once the stains and cultures come back, therapy can be directed based on microbe identification and sensitivities. I especially like compounded topical vancomycin 50 mg/mL for staph species, which remains 100% effective against MRSA and MRSE.
These patients require careful follow-up and usually are seen every day until a clinical response is noted. If the cornea perforates, cyanoacrylate glue is appropriate. I like the eye to heal fully and rarely perform a therapeutic penetrating keratoplasty unless the patient has an atypical infection that is not responding, such as Pseudomonas, fungus or Acanthamoeba. For most ophthalmologists, referral to a tertiary care center is wise if the infection is unresponsive to initial therapy.
While it may be a difficult patient discussion, many of these patients eventually need excimer laser phototherapeutic keratectomy, often with a PRK card, to treat secondary corneal haze or scar. I also prefer PRK over my penetrating and lamellar keratoplasties when needed for high astigmatism or anisometropia. Mitomycin C for 30 to 60 seconds is used to reduce haze. More aggressive antibiotic prophylaxis is indicated in a patient with a history of infection and if the patient is a MRSA or MRSE carrier. Bactroban nasal ointment (mupirocin) twice daily for 5 days preoperative is also useful.
Fortunately, infections after PRK and LASIK are rare, but when they occur they deserve prompt diagnosis, including corneal scraping for stain and culture, followed by aggressive therapy.
Disclosure: Lindstrom reports relevant financial disclosures for Bausch + Lomb, Alcon, Novartis, Allergan and Imprimis.