July 2007




The typical endophthalmitis patient

by Matt Young EyeWorld Contributing Editor




Medicare based study finds some common characteristics

Because of its rarity, endophthalmitis usually evades broad-based analysis. That’s not the case in one recent study published in the online version of Ophthalmology. Alan L. Robin, M.D., associate professor of ophthalmology and associate professor of international health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, and colleagues evaluated Medicare records to determine the costs of endophthalmitis. In doing so, the researchers reviewed 417 endophthalmitis cases among 139,775 cataract surgeries. Due to the breadth of the research, the researchers yielded a few insights into who endophthalmitis patients typically are and how often the disease presents.

Who gets it, and how often?

The researchers collected their data from the Medicare Beneficiary Encrypted Files, which is a 5% sample of all Medicare enrollees and is representative of U.S. citizens 65 or older. Those affected by endophthalmitis more frequently had glaucoma (12.7% of patients) compared with cataract (9.4% of patients). They also more frequently had disorders of the globe (1.4% versus 0.1%) and other ophthalmic disorders (14.9% versus 11.0%). These differences all were statistically significant. However, the researchers were not more specific about disorders of the globe and other ophthalmic disorders.

“We do not know of data to suggest that conditions included in the latter two categories, such as hypotony, degenerative conditions of the globe, chorioretinal inflammations, or night blindness, necessarily would affect costs and thus did not control for differences in these comorbid conditions,” Dr. Robin reported. Of note, endophthalmitis cases and the control group were similar with respect to sex, race, and mean age. There also was no statistically significant difference between cases and controls with respect to retinal detachments and defects, diabetic retinopathy, retinal vascular occlusion, macular degeneration, uveitis, disorders of the vitreous body, and vision loss. Despite their findings, the researchers still noted that “little is known about typical characteristics of patients affected with endophthalmitis.”

Their data also put the incidence of endophthalmitis at 0.3%, which is higher than the often quoted 0.1% average incidence of the disease. This gives further credence to either a recent rising incidence of endophthalmitis or that conventional wisdom has been off the mark.

Analyzing this

Mark Packer, M.D., clinical associate professor, Casey Eye Institute, Oregon Health & Science University, Portland, corroborated the study’s findings, saying that endophthalmitis infection rates are generally higher in complicated cases. “Eyes that are healthy tend to remain healthy, and eyes that are sick tend to get sicker still,” Dr. Packer said. He also noted other surgical circumstances—and patient types—in which the risk of endophthalmitis is higher. “A broken capsule in cataract surgery will increase the risk simply because you have a longer procedure,” Dr. Packer said. “The eye is open for a longer period of time, which increases the risk of infection. You also may end up with a vitrectomy. And if you have residual vitreous or strands of vitreous to the internal part of the incision, that may provide a route for bacteria to get into the eye.”

Also, cases that take longer because of poor visualization like very hazy corneas that are more difficult to see through could increase the risk, Dr. Packer said. Even smaller pupils, which make the procedure more difficult, could make a post-op endophthalmitis more likely. Dr. Packer tends to think any preexisting comorbidity of the anterior segment, ocular surface, or lacrimal system increases the risk of endophthalmitis. “A classic case is a nasolacrimal duct obstruction where you’re not getting adequate flow of the tear film so you have a stagnant pool of tears sitting there and that’s just a breeding ground for bacteria,” Dr. Packer said. “Eyelid malposition—ectropion or entropion—also for the same reason tends to leave stagnant tear lakes, which like stagnant water tends to grow bugs.”

Other ocular surface issues like dry eye, lacrimal insufficiency, and Sjцgren’s disease can also increase risk “because you’re not getting an adequate flow of tears over the surface of the eye, which keeps the bacteria moving along on their way.”

A patient with a weakened cornea, such as one with keratoconus, could also be at higher risk for endophthalmitis. Any previous intraocular surgery increases the risk for endophthalmitis, Dr. Packer said.

Editors’ note: Dr. Robin has no financial interests related to his study. Authors from Exponent Inc. (Alexandria, Va.) and Alcon (Fort Worth, Texas) also participated in writing this study. Dr. Packer has no financial interests related to his comments.

Contact Information

Packer: 541-687-2110, mpacker@finemd.com

Robin: 410-377-2422, glaucomaexpert@cs.com

The typical endophthalmitis patient The typical endophthalmitis patient
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