Attention to lids, ocular surface minimizes risk of postop endophthalmitis

Marguerite B. McDonald

Wide-spectrum antibiotics, smaller and more precise corneal incisions, and emerging drug delivery technologies may help clinicians prevent or eliminate postoperative endophthalmitis after cataract surgery, experts said. Meticulous lid management is critical to preventing or minimizing infection.

Marguerite B. McDonald, MD, OSN Refractive Surgery Board Member, emphasized the importance of thoroughly eliminating microbes on the ocular surface before they infiltrate a cataract incision.

“It’s great if your drug kills bacteria inside the eye, but most of us think that the battle is won on the surface of the eye,” Dr. McDonald said. “You want to kill them before they even get close to the lips of the clear corneal incision.”

Eric D. Donnenfeld, MD, OSN Cornea/External Disease Board Member, cited a study showing that organisms that caused endophthalmitis originated primarily in the patient’s lid flora.

“By reducing blepharitis and lid bacteria, you can reduce the risk of infection,” Dr. Donnenfeld said. “So, I treat lid disease very aggressively. I’ve been using topical azithromycin in patients with blepharitis before surgery. I apply it once a day and I know that it significantly reduces bacterial carriage as well as opening the meibomian gland orifices to reduce the oils that act as food for these bacteria.”

Drug resistance

Antibiotic resistance is increasingly problematic in patients with ocular infections after cataract and refractive surgery, Dr. Donnenfeld said.

Research has shown that methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermis (MRSE) are the most common causes of infection after LASIK and PRK, Dr. Donnenfeld said.

In a study published in the American Journal of Ophthalmology in 2007, Dr. Donnenfeld and colleagues found that 13 eyes of 12 patients developed MRSA keratitis after undergoing refractive surgery. “These patients have a reduced visual potential because of their resistance to current antibiotics, and they can have significant vision loss associated with that,” he said.

In 2008, an American Society of Cataract and Refractive Surgery survey showed that staph was the most common infectious microorganism, accounting for almost 50% of infections after LASIK.

“It’s a growing problem,” Dr. McDonald said. “Resistance to the fluoroquinolone antibiotics is growing due to their extensive use in medicine and agriculture.”

Fluoroquinolones are effective against a variety of infections, but switching to vancomycin is advised when a fluoroquinolone proves ineffective against MRSA, Dr. McDonald said.

Dr. Donnenfeld referred to a study that showed the rate of methicillin resistance doubled between ages 50 and 80 years.

“Our feeling is that it’s probably due to decreased immunity, older age increasing the rate of resistance because they are exposed to more bacteria over the course of a lifetime, probably more blepharitis, which accounts for the lid disease that causes the [infection],” he said. “And maybe they’ve been exposed to more antibiotics in the course of their lifetime.”

Existing antibiotics such as ophthalmic Neosporin (bacitracin, neomycin and polymyxin B) and Bactroban (mupirocin, SmithKline Beecham) are effective against MRSA and MRSE, Dr. Donnenfeld said.

“[Bactroban] is available over the counter but it also comes in a gel that’s used for nasal MRSA carriage,” he said. “It actually has a [U.S. Food and Drug Administration] indication for treating MRSA. I will apply that to the lid margins of patients who are known carriers of MRSA.”

Intracameral antibiotics

Intracameral antibiotics have gained favor in Europe but are somewhat controversial in the U.S.

“I use intracameral vancomycin in all of my cataract surgeries because it places the antibiotics in the tissue that’s responsible for endophthalmitis,” Dr. Donnenfeld said.

Dr. McDonald takes a positive but cautious view of intracameral antibiotics.

“In general, I’m in favor of them,” Dr. McDonald said. “However, some company should make sterile, single-use-only ampules so the doctors don’t have to mix stuff up. There is a danger there. You really have to have a pharmacy mix your stuff up, and it has to be handled very, very carefully. But single-use-only ampules would be great.”

Currently, Dr. McDonald said she does not use intracameral antibiotics, except for some vancomycin in the infusion fluid without a bolus.

“And we do have that made up, of course, by a professional pharmacy,” Dr. McDonald said. “So, I’ll do the bolus at the end as soon as we get the ampules.”

Wound architecture, drug delivery

Small, self-sealing corneal incisions reduce the risk of endophthalmitis, Dr. Donnenfeld said.

“I like improved wound architecture,” he said. “A self-sealing wound is very important. … And the new femtosecond cataract surgical incisions will be perfect incisions that should basically never leak.”

In addition, sustained drug delivery systems such as contact lenses and punctal plugs may provide further defense against infection, Dr. Donnenfeld said.

“In the future, sustained delivery systems such as intraocular lenses that are coated with antibiotics that release antibiotics over time would be very good,” he said.

Hydrogel material is not an ideal drug reservoir, but new engineered materials may prove more effective, Dr. McDonald said.

“If the new nanotechnology lenses can be cost-effective and will truly elute drug at a steady rate over a long period of time, that would be wonderful, especially if they’re clear.”

The ocular bandage from Ocular Therapeutix, a synthetic liquid hydrogel bandage that temporarily covers a corneal incision, offers the added benefit of enhancing wound sealing and preventing wound leakage, Dr. Donnenfeld said.

He advocates an ocular bandage that seals the incision and delivers antibiotics. “Re-sealing the wound and having antibiotics that attach to the wound, I think, would be a great delivery system. I’m very optimistic about that indication as well,” he said. – by Matt Hasson

Click here for the Guide to Anti-infective Medication.

References:

• Solomon R, Donnenfeld ED, Perry HD, et al. Methicillin-resistant Staphylococcus aureus infectious keratitis following refractive surgery. Am J Ophthalmol. 2007;143(4):629-634.
• Speaker MG, Milch FA, Shah MK, Eisner W, Kreiswirth BN. Role of external bacterial flora in the pathogenesis of acute postoperative endophthalmitis. Ophthalmol. 1991;98(5):639-649.

• Eric D. Donnenfeld, MD, can be reached at Ophthalmic Consultants of Long Island, 2000 North Village Ave., Rockville Centre, NY 11570; 516-766-2519; fax: 516-766-3714; e-mail: eddoph@aol.com.
• Marguerite B. McDonald, MD, can be reached at Ophthalmic Consultants of Long Island, 266 Merrick Road, Lynbrook, NY 11563; 516-593-7709; fax: 504-232-3641; e-mail: margueritemcdmd@aol.com.

Endophthalmitis is a relatively rare but devastating complication associated with cataract surgery. In order to minimize the potential risk of endophthalmitis, lid hygiene prior to cataract surgery is recommended by most surgeons. There are two primary forms of lid disease: anterior and posterior blepharitis. Anterior blepharitis typically presents as collarettes, crusting and debris on the lid margin associated with staph and seborrhea. Posterior blepharitis, also known as meibomitis, typically presents as inspissated meibomian glands and turbid secretions.

Lid hygiene protocols vary depending upon the surgeon and the degree of lid disease. Some practices recommend lid hygiene (lid scrubs and warm compresses) for all patients prior to surgery, varying from a few days to a couple of weeks prior to surgery. In more severe forms of anterior blepharitis, patients may additionally be placed on topical antibiotic therapy such as Azasite (1% azithromycin ophthalmic solution, Inspire Pharmaceuticals) and bacitracin ointment and/or oral doxycycline.

Patients who have posterior blepharitis often have disrupted production of meibum, which can result in a poor quality tear film and evaporative dry eye. With the introduction of a variety of premium IOLs, a stable and good quality tear film is necessary for increased patient success. Patients who have posterior blepharitis are often treated with azithromycin every night at bedtime for a month and may also be placed on Restasis (0.05% cyclosporine A, Allergan) twice daily to ensure a good quality tear film.

Recent advances in contact lens technology have produced contacts that are preloaded with a variety of nutraceutical and pharmaceutical agents. In the works are contact lenses that will be preloaded with antibiotics that may be utilized postoperatively to ensure a constant and continual supply of antibiotics to the eye.

– Blair Lonsberry, MS, OD, MEd, FAAO
Clinic Director, Portland Vision Center, Pacific University of Oregon College of Optometry, Portland, Ore.